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Biomedical subjects

H Connor

Publications and source records attributed to H Connor.

At least 55 records · Page 3Linked to original sources
PubMed1982

Quantitative aspects of L(+)-lactate metabolism in human beings.

The production rate of endogenous L(+)-lactate in the resting human being can be calculated from results of experiments during which isotopic or unlabelled lactate is infused. The merits of the different experimental techniques are discussed, although all published methods have given similar results, namely a resting production rate of about 1.3 mol . (70 kg body wt)-1 . 24 h-1. This result is similar to that found in sheep, but lower than that in dogs and rats. L(+)-lactate production in human subjects is unchanged after fasting for 36-168 h, a finding which contrasts with some animal experiments. It is not known whether this represents a true species difference or a difference in diet. Net splanchnic uptake of L(+)-lactate in the resting human being is about 0.4 mol 24 h-1 although the normal liver has the capacity to metabolize more than this. The kidney is an important site of L(+)-lactate utilization in rats, but there is no information about its role in normal human beings. There are conflicting reports concerning the uptake of L(+)-lactate by resting skeletal muscle, but there is no evidence that resting muscle can metabolize lactate.

Animals↗
PubMed1982

The role of altered lactate kinetics in the pathogenesis of type B lactic acidosis.

Of the two types of lactic acidosis, Type B is the most difficult to explain in terms of mechanisms of lactic acid accumulation because the tissue hypoxia that accompanies Type A is not present except as a terminal event. The methods of pharmacokinetics show that for lactate to accumulate to an extent that would disturb acid-base balance, either lactate synthesis or lactate removal would have to be increased or decreased, respectively, by about 7-10-fold. To produce lactic acidosis within a few hours, synthesis would have to increase at the same time as clearance decreased. At normal contribution of the liver to the total lactate clearance (30%-40%), a total cessation of hepatic lactate clearance would not result in lactic acidosis without a concomitant rise in the rate of lactate synthesis. Again, to produce an acidosis this increase would have to be about 8-fold at a normal fractional hepatic clearance. The control of hepatic lactate uptake is discussed in the light of the relatively low hepatic extraction of lactate and in relation to to two main models of hepatic drug (lactate) clearance; the 'well-stirred' and 'parallel-tube' models.

Acidosis↗
PubMed1982

A model of L(+)-lactate metabolism in normal man.

Mathematical models were used to study the elimination of L(+)-lactate during and after an intravenous load of unlabelled sodium L(+)-lactate in 20 normal postprandial subjects. Clearance of L(+)-lactate from blood was 17.9 +/- 1.1 ml (kg BW)-1 min-1 and the endogenous production rate of L(+)-lactate at rest was 1.38 +/- 0.16 mol (70 kg BW)-1 24 h-1. Clearance and production were unchanged after a 36-hour fast in 4 subjects. Renal excretion of L(+)-lactate accounted for less than 1.2% of the infused load. Clearance of L(+)-lactate was closely related to the pre-infusion concentrations of ketone bodies and alanine.

Adult↗
PubMed1982

Utilization of L(+) lactate in patients with liver disease.

Clearance of intravenously infused sodium L(+) lactate was slower in 37 patients with liver disease (14.5 +/- 0.9 ml (kg BW)-1min-1) than in 20 normal subjects (17.9 +/- 1.1 ml (kg BW)-1min-1). This difference is statistically significant (2p less than 0.0125). Impairment of L(+) lactate utilization was not related to the aetiology of the liver disease. Both increased production and decreased utilization of L(+) lactate were found in patients with secondary malignancy of the liver. Penetration of L(+) lactate into ascitic fluid was variable and estimates of L(+) lactate utilization may be unreliable if ascites is present.

Adult↗
PubMed1981

Muscle protein breakdown in thyrotoxicosis assessed by urinary 3-methylhistidine excretion.

Urinary 3-methylhistidine (3MH) excretion has been studied in 20 thyrotoxic patients before, during and after treatment. 3MH excretion was high on diagnosis and fell significantly, when the patients had been rendered euthyroid, to levels measured in a control group. There was a significant linear correlation between 3MH excretion and free thyroxine index. The calculated muscle protein breakdown and 3MH/creatinine molar ratio also fell significantly after treatment of thyrotoxicosis.

Adult↗
PubMed1980

Salbutamol and ketonuria in pregnancy. Case report.

A patient is described who had heavy ketonuria without associated glycosuria during treatment with salbutamol in pregnancy. Blood glucose and ketone concentrations were normal while urine secretion of ketone bodies was increased. This suggests that ketonuria resulted from an altered renal threshold rather than a change in intermediary metabolism. Plasma ketone concentration should be measured before stopping salbutamol on the basis of ketonuria alone.

Adult↗
PubMed1979

An insulinoma presenting with reactive hypoglycaemia.

A 57-year-old woman presented with symptoms which were cured by the removal of an insulinoma. The case was atypical in that symptomatic hypoglycaemia occurred only after meals or glucose administration but never during fasting, and thus if plasma insulin activity had not been measured an incorrect diagnosis of reactive hypoglycaemia might have been made on the basis of symptoms and oral glucose-tolerance test. Reactive hypoglycaemia resulted from an increased rate of glucose assimilation and possibly also from a decreased rate of gluconeogenesis due to the immense insulin secretion provoked by glucose or food. The findings suggest that a diagnosis of hypoglycaemia should not be made until the possibility of an insulinoma has been excluded by measurement of plasma insulin activity during a period of hypoglycaemia.

Adenoma, Islet Cell↗
PubMed1978

Oral methionine loading as a cause of acute serum folate deficiency: its relevance to parenteral nutrition.

Oral methionine supplements (8.0 g daily for 4 days) were given to five normal volunteers who continued to eat their usual diet. This treatment resulted in a significant fall in serum folate concentration. Three days after the end of treatment concentrations had not completely returned to control values. The fall in concentration was prevented by giving oral folic acid supplements. It is suggested that folic acid supplements should be given to patients who are receiving intravenous infusions of amino acid mixtures.

Administration, Oral↗
PubMedDate not supplied

Repetitive ulceration in neuropathic patients.

METHODS: In a retrospective study, 83 patients with diabetic neuropathic foot ulceration were classified into two groups: those with a higher rate of ulceration defined as >/=3.5 ulcers per foot per 10 years (group H) and those with a lower rate of <3.5 ulcers per foot per 10 years (group L). RESULTS: Higher risk was associated with neuroarthropathy, higher mean HbA(1c), men who lived alone, alcohol misuse by men, poor compliance with footwear, footcare and with non-foot aspects of diabetic self-care, higher non-attendance rates and, in patients with type 1 diabetes, delay in reporting new foot problems. CONCLUSIONS: Reduction in ulcer recurrence rates will require improved orthotic provision in patients with neuroarthropathy and new methods to achieve behavioural change in other higher risk patients.

Diabetes Mellitus, Type 1↗
PubMedDate not supplied

Medieval uroscopy and its representation on misericords--part 1: Uroscopy.

The art of uroscopy involved the visual inspection of urine in a specially shaped flask called a matula. By the fourteenth century it had become an integral part of the assessment of the patient's humoral balance, which was the linchpin of both diagnosis and management in medieval medical practice, and the matula became the symbol of a physician. However, the practice was open to abuse by unscrupulous physicians, who offered treatment solely on the basis of uroscopy without even seeing the patient. Further abuse occurred as Latin texts on the subject were translated into the vernacular by unqualified imposters. Although more orthodox practitioners and the College of Physicians tried hard to distance themselves from the practice, the matula became a symbol of ridicule.

Ethics, Medical↗
PubMedDate not supplied

Coping with pressures in acute medicine--the second RCP consultant questionnaire survey.

The second questionnaire survey of consultant physicians involved in acute unselected takes in 1999 achieved a 76% response rate, and the results have been compared with those from the first survey of 1997. The proportion of consultants whose trainees worked partial shifts had increased from 42% to 61%, although these patterns of duty were adjudged to have detrimental effects on the quality and continuity of care, and on junior staff education and training. The benefits of ward-based systems were counterbalanced by their disadvantages, but introductions of admission wards and assessment units were considered a resounding success. The number of hospitals with 'physician of the week' schemes had increased from 12 to 23, but opinion of their value was sharply divided. The provision and competence of all grades of locums was identified as an increasing problem. Seventy per cent of respondents stated that they would never participate in 'hands-on' emergency care, although 86% thought that future consultants might have to do so. Seventy-nine per cent reported increases in the pressures of their posts and in their working hours, and the tensions between general and specialist duties were highlighted. Most consultants considered that the only long-term solution to the staffing crisis was a marked expansion in the numbers of all grades of medical staff.

Adult↗