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January 1, 1854

Mapping disease: John Snow and Cholera

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The first usage of epidemiology and public health occurs when John Snow talked to local London residents of a cholera outbreak and determined they were near the Broad Street water pump, which had become infected by choleric sewage.

"A major outbreak of cholera reached the district of Soho, London, in August 1854. This was the third cholera outbreak in London, having previously occurred in 1832 and 1849. In the mid-19th century, Soho had a serious problem with filth due to the large influx of people and a lack of proper sanitary services: the London sewer system had not reached Soho at this point and drainage was poor throughout London. It was common at the time to have a cesspit under most homes.

By talking to local residents (with the help of the Reverend Henry Whitehead), Snow identified the source of the outbreak as the contaminated public water pump on Broad Street (nowBroadwick Street). He did this by mapping the deaths from cholera, and noted that they were mostly people whose nearest access to water was the Broad Street pump (see map below from On the Mode of Communication of Cholera, 2nd ed.). His studies of the pattern of the disease were convincing enough to persuade the local council to disable the well pump by removing its handle. This action has been credited with contributing significantly to the containment of the disease in the area. It was later discovered that the water for the pump was polluted by sewage contaminated with cholera from a nearby cesspit."

However, Snow’s theory was not new in 1854. He had argued earlier that it was not an airborne disease in his published essay, On the Mode of Communication of Cholera, in 1849. The germ theory was not developed at this point, so Snow was unaware of the mechanism by which the disease was transmitted, but evidence led him to deduce in 1854 that it was not due to breathing in foul air. In 1855 a second edition was published, incorporating the results of his investigation of the Soho epidemic of 1854.

Hand pumps like that on Broad Street were not the only source of Londoners’ water, or Snow’s only object of study during the 1854 cholera outbreak. The Lambeth Water Company and the Southwark and Vauxhall Water Company were both supplying mechanically-pumped water to residents of South London (see map below from Tracts 376). Snow recorded cholera attacks in this area, alongside information about the water supply to the houses affected. He showed that the Southwark and Vauxhall Waterworks Company was taking water from sewage-polluted sections of the Thames and delivering the water to homes, leading to an increased incidence of cholera.

January 1, 1919

Studies on Blood Sugar - Effects upon the blood sugar of the repeated indigestion of glucose by Louis Hamman

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Staub-Traugott effect is shown where if two consecutive doses of glucose are given to a healthy subject the hyperglycaemia resulting from the second dose is lower than that after the first.

The Staub-Traugott Phenomenon

Up to the present the masterly work of Allen and his collaborators has dominated the conception of diabetes mellitus, but recently another line of research has begun to turn thought in a different direction. In 1919 Hamman and Hirschman described the phenomenon which is now usually referred to as the Staub-Traugott effect. They showed that if two consecutive doses of glucose are given to a healthy subject the hyperglycaemia resulting from the second dose is lower than that after the first.


Studies on Blood Sugar - Effects upon the blood sugar of the repeated indigestion of glucose by Louis Hamman


In a communication to the Archives of Internal Medicine Hamman and Hirschmann have demonstrated the blood-sugar response Ito the ingestion of a single large dose of glucose in normal persons and in others suffering from various diseases. For this study 100 grams of glucose were administered in the early morning after the night fast, and the blood sugar and urine sugar estimated at short intervals thereafter. It was demonstrated that there are two important types of reaction, the normal and the diabetic. There is still a third type, not nearly so clearly distinguished as these two, the reaction of increased carbohydrate tolerance. Although the reaction in normal persons varies in different individuals and in the same individual under different circumstances, its general characters are as follows: The blood sugar rises rapidly, but seldom exceeds 0.15 per cent; it falls somewhat more slowly to the original level, the whole reaction being over in less than two hours. In diabetics the rise is higher and longer sustained. If the blood sugar surpasses 0.18 per cent, sugar usually appears in the urine, but sometimes it appears at a somewhat lower level; at other times it fails to appear, even though 0.2 per cent of blood sugar is exceeded. From two to five hours pass before the blood sugar reaches the original fasting level. When the carbohydrate tolerance is increased, there is only an insignificant rise in the blood sugar, which has usually a low fasting level.

January 1, 1954

Observations on Blood Pressure in Eskimos

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When comparing the Eskimo men with white men of corresponding age, it is observed that both the systolic and diastolic blood pressures are lower in Eskimos than in Whites. It appears to be the impression of most physicians who have had occasion to examine large numbers of Eskimos, that the blood pressure in Eskimos is lower than in normal Whites of corresponding age.

It appears to be the impression of most physicians who have had occasion to examine large numbers of Eskimos, that the blood pressure in Eskimos is lower than in normal Whites of corresponding age (P. B. Haggland, M. D. , E. S. Rabeau, M. D. , and E. Albrecht, M. D. , personal communications). Abnormally elevated blood pressures (systolic blood pressure in the order of 170 mm or higher) are apparently quite rare. Thus, in the 213 Eskimo patients who were subject to medical examination by the author during a two-year period in Alaska, the blood pressure was measured in 1 17 cases, and only one of the patients had systolic blood pressure above 145 mm. 


In contrast to this, Saxtorph (quoted by A. Bertelsen, 1940) reported in 1926 that he had seen a considerable number of cases of hypertensio arterial is, both in old and middle-aged Greenland Eskimos. In 12 cases he measured blood pressures between 200 and 240 mm. 


Thomas ( 1927) on the other hand examined 142 Greenland Eskimos, 40-60 years of age, and found the average blood pressure to be 129/76 mm, with a single case of 170/ 1 00. He concluded that hypertension with associated complications is extremely rare among Eskimos. 


Holbeck (quoted by Bertelsen, 1940) has reported that the average systolic blood pressure in Greenland Eskimos, between 40 and 55 years uf age, was 141 in men and 131 in women. According to Bertelsen ( 1940) Svendsen examined, in 1930, the blood pressure of 106 Eskimos taken at random, some of whom had active pulmonary tuberculosis. He made the following findings: 15-30 years of age: 120/70 mm; 30-50 years ()f age: 137/77 mm; 50 years of age or over: 167/82 mm. Bertelsen (1940) concludes, on the basis of his experiences in Greenland, that the average blood pressure does not appear to deviate from that of Whites of corresponding age. 


Probably the most extensive study of Eskimo blood pressure has been reported by Hoygaard (1941). He measured the blood pressure systematically of 283 Angmagssalik Eskimos, South East Greenland, of both sexes, living on their primitive diet, using the standard technique in lying or sitting position at least one hour after exercise. He found no material difference between males and females. Twelve persons out of 283 (4%) had a systolic blood pressure of 150 or higher; only two subjects had as much as 168 mm Hg. (Table 1). He concludes that hypertonia is not common. 


According to MacMillan ( 1951) Or. E. Morse found no instance of high blood pressure among the Thule Eskimos during the Bowdoin's voyage to Greenland in 1950. 


In the case of Canadian Eskimos, Brown (1 951) states with regard to the Southampton Island and the Igloolik Eskimos: "Arterial hypertension has also been found both in the group at Southampton Island and in the group at Igloolik." However, in the 63 Eskimos living in the vicinity of Chesterfield Inlet (30 males and 33 females) examined by Crile and Quiring ( 1939) the average blood pressure in the males (average age 38 years) was: systolic pressure 1 19 mm, diastolic pressure 75. In the females (average age 31 years) the figures were 1 12 and 72 respectively. The average pulse rate was 62-69 in the males and 79-82 in the females. These authors conclude that "the blood pressure for both the males and the females is lower than that of Whites of corresponding age, the pulse rate corresponds rather closely to that of White individuals". 


Heinbecker (193 1) reports an average pulse rate of 64 in 5 Eskimos (4 females and 1 male, 15-50 years of age) from Baffin Island. Bollerud, et at. ( 1950) report an average pulse rate of 58 in their 23 male St. Lawrence Island Eskimos, 17--41 years old. 


In connection with extensive studies on the patho-physiology of Eskimos which were in progress at the Arctic Aeromedical Laboratory as part of a survey of human adaptation to cold, we had an opportunity of recording various physical and physiological measurements during a two-year period 1950-1952. In this paper we are only concerned with blood pressure. pulse rate and age. 


4. Results and Discussion. 


The results from all 104 Eskimo subjects of both sexes are presented in Table 2. The average age is just over 29 years, but the ages vary widely from 3 to 75. However, of the 104 subjects, 73 were between 15 and 40 years old and only 13 were below 15 years. 


From this table it is observed that the pulse rate at rest, when considering the mean figure for all observations in each subject, is 71 beats per minute, but the figures show considerable individual variations. If only the final reading is considered, the mean value is 67 beats per minute, ranging from 44 to 120. The average systolic and diastolic blood pressures in Eskimos of both sexes, when considering the mean values of all readings in each subject, were 110 and 71 respectively. The mean values of the final blood pressure readings obtained when the lower level was established after several repeated examinations, were slightly less, the systolic pressure being 107 and the diastolic pressure 69. The range of these measurements is considerable. 


Thus the resting systolic blood pressure varies from a minimum value of 84 to a maximum value of 140; the diastolic blood pressure varies from 56 to 100. Only one subject, a 14-year old boy, showed as high an average value for the systolic blood pressure as 140. No systolic blood pressure higher than 162 mm was recorded in this series. 80.76 o/c of the recorded systolic blood pressures were below 116 mm. 


Table 3 shows the results of similar measurements in 40 normal white men examined in Alaska by the same investigator. In this material the average age is 23 years. It appears that the figures for pulse rate are very similar to the corresponding figures for Eskimos. The mean figures for blood pressure are higher than in the Eskimos, both in the case of systolic and diastolic pressure, and in the case of both the mean values of all observations as well as in the case of the final values, recorded when the lower level had been established as the result of repeated examinations. It is observed that the figures, both for pulse rate and blood pressure in these White subjects, are lower than the figures published by McKiniay and Walker (1935) for 566 normal white men with a mean age of 23.2 years. The difference is over 5 times the standard error, both in the case of pulse rate and blood pressure. 


The wide range of "normal" variations in blood pressure in Whites, has been emphasized by McKinlay and Walker (1935). According to American sources the average values for systolic pressure in healthy males, as measured in the brachial artery with the individual at rest, vary from 100 to 120 in early manhood, from 125 to 136 in the middle years of adult life, and from 145 to 150 above the age of sixty years. 


The range of individual measurements. however, may show much wider variations. Alvarez, quoted by McKinlay and Walker (1935), found that the systolic blood pressure in 6,000 University students and graduates between the ages of 16 and 40 years may be as low as 85 mm or as high as 190 mm. He concludes that 22 per cent of men have a systolic blood pressure exceeding 140 mm and that one man in every forty has Cl systolic blood pressure higher than 160 ml. According to Diehl and Sutherland (1925), nine per cent of male students, 16-40 years of age, at the University of Minnesota had blood pressures over 140 mm. None of our Eskimo men, 15-40 years old. had mean blood pressures over 140 ml. 


As a rule, the lowest blood pressure readings were obtained at the fourth examination in Whites, but ne,t until the fifth examination in Eskimos. 


McKinlay and Walker (1935) had examined the variability and interrelationship of heart rate, systolic and diastolic blood pressure, pulse pressure and age in healthy men of ages ranging from 16 to 40. They conclude that within the period of life studied, age is not of great importance in determining the level of any of these factors. They find definitely significant, positive relationship between age and both systolic and diastolic blood pressure. but in such a degree as to form anything like a reasonably accurate basis for prediction. They find positive, but not very intimate, association between heart rate and blood pressure. 


In Tables 4, 5 and 6 our data are separated into three age groups: 15-25 years, 26-40 years, and over 40 years old. 


Twenty-five of the male Eskimos were between 15 and 25 years old. the average age being slightly over 21 years in this group. The same number of male Eskimos fell in the second age group: 26-40 years, the average age in this group being 33 years. Only twelve of the male Eskimo subjects were over 40 years old. 


There is no difference in the mean value of all readings in each subject for the 15-25-year-old group as compared with the 26-40- year-old group, but the mean value for the group over 40 years old is higher than the first two groups. The difference is 4 times the standard error, and is therefore probably statistically significant. 


The data for the 29 Eskimo women, divided into the three age groups: 15-25 years old (12 subjects), 26-40 years old (11 subjects), and over 40 years old (6 subjects), are given in Table 5. On the basis of this limited material it appears that the average blood pressure in Eskimo women is somewhat higher than in Eskimo men, but this difference is not statistically significant. There is also a tendency towards increased blood pressure with increasing age in Eskimo women. 


Of the 40 white men, 34 fell into the first age group (15-25 years) and 5 in the second age group (26-40 years) while only one subject was over 40 years old. If we compare these white men with Eskimo men of corresponding age, it is observed that the average blood pressure is slightly higher in Whites than in Eskimos but the difference is too small to be significant statistically (less than 3 times the standard error). The mean of the lowest measured blood pressure in each subject in the first age group is considerably lower in Eskimos than in Whites, however. The difference is about 4 times the standard error, and may be statistically significant. The number of subjects is too small, nevertheless, to allow any definite conclusion to be drawn from this material. 


It should also be noted that a larger proportion of the blood pressure measurements were recorded in the lying position in the Eskimos (70 C,c) than is the case in the Whites (25 o/c) and since the blood pressure tends to be lower in the lying position (Tables 7 and 8), this may partly account for the difference, although the difference between sitting and lying blood pressure in Whites in this material is not significant statistically. Thus, in Whites 15-25 years old, the difference between the means for sitting and lying systolic blood pressure is 5 mm, which is less than twice the standard error, as is also the case when comparing the diastolic blood pressure in the sitting and lying position. However, out of the 24 lowest measured blood pressures in Whites 15-25 years old, 76.47 per cent were measured in the lying pOSitIOn, and of the highest measured blood pressures in the same subjects, 97.06 per cent were measured in the sitting position. It may be noted however that in Eskimos the difference between sitting and lying blood pressure is about 3 times the standard error. 


In Whites 15-25 years old, the mean pulse rate is 72 measured sitting, and only 58 when measured lying. The difference is 4 times the standard error, and may therefore be considered significant in a statistical sense, although the number of observations is very small. The range of the pulse rate measured sitting is 68-86, against 51-67 measured lying.


From Table 10 it appears that the Kotzebue and Gambell Eskimos in the age group 26-40 years have a lower mean blood pressure than the corresponding age groups from Anaktuvuk Pass and Barter Island. The difference between the Gambell and the Anaktuvuk Pass groups (the groups showing the most pronounced difference), as regards the means of the lowest measured blood pressures, is 12 mm, and the standard error is 3.20. Thus, the difference is over three times the standard error. However, the material is too small to allow any conclusion. No significant difference was detected in the blood pressure in Eskimos 15 -25 years old from the 4 different settlements (Table 9). 


5. Summary and Conclusion. 


735 blood pressure and pulse rate measurements were made in a consecutive series of 104 Eskimos (75 males and 29 females) from 4 different Eskimo settlements in Alaska. Similar measurements were made in 40 normal white men for comparison. 


In Eskimos the mean resting systolic blood pressure varied from a minimum value of 84 to a maximum value of 140. No systolic blood pressure higher than 162 mm was ever recorded in our Eskimo subjects. 80 o/c of the recorded systolic blood pressures were below 1 16 mm. The mean diastolic blood pressures varied from 56 to 100. In Eskimos the mean blood pressure is somewhat higher in women than in men of corresponding age although the difference is not statistically significant, and there is a tendency towards increased blood pressure with increasing age. 


In Eskimo men the mean blood pressure was 108/69 at ages 15-40 years, and 119/77 above 40 years of age. In Eskimo women the figures were 111/71 and 122 /74 respectively. When comparing the Eskimo men with white men of corresponding age, it is observed that both the systolic and diastolic blood pressures are lower in Eskimos than in Whites. This difference appears to be statistically significant in the case of the lowest measured blood pressure in each subject in the two groups. The mean pulse rates in Eskimos at rest were not materially different from the corresponding figures for Whites.

January 1, 1972

John Yudkin

Pure, White, and Deadly

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Professor Yudkin describes experiments that lead him to believe sugar is toxic.

"John Yudkin was one of the first to point out the dangers of sugar when he published the original edition of Pure, White, and Deadly in 1972. Now, in this extensively rewritten and expanded edition, he reveals the new evidence about the dangers of sugar and its drastic consquences for our health. In everyday language Professor Yudkin explains how sugar consumption is linked to diabetes, heart and liver disease, dental caries and other conditions. He pays particular attention to its effects on young children and shows how they, like everyone else, can benefit from reduced sugar intake. He also examines the role of the sugar industry, which has made strenous efforts to dismiss the case against sugar."

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