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Biomedical subjects

J B Warren

Publications and source records attributed to J B Warren.

89 records · Page 5Linked to original sources
PubMed1984

Urine sugar reagent tablet ingestion causing gastric and duodenal ulceration.

The accidental or intentional ingestion of urine sugar reagent (Clinitest) tablets, a potent caustic, has been reported to cause severe esophageal mucosal damage and stricture formation. Gastric mucosal damage was reported once before in a man who intentionally ingested 26 Clinitest tablets. We encountered a case of accidental Clinitest tablet ingestion causing gastric and duodenal ulceration without esophageal damage, a previously undescribed complication of inadvertent Clinitest tablet ingestion. Our case reemphasizes the role of early fiberoptic endoscopy in the evaluation of caustic ingestions.

Accidents↗
PubMed1983

A comparison of the bronchodilator and vasopressor effects of exercise levels of adrenaline in man.

1. Plasma adrenaline was measured at rest and on exercise in six normal, non-atopic subjects. The exercise test produced a minimum tachycardia of 158 beats/min and a mean plasma adrenaline level of 1.89 nmol/l. 2. On a separate occasion, two doses of L-adrenaline (0.025 micrograms min-1 kg-1 and 0.05 micrograms min-1 kg-1) were infused in the same subjects at rest to produce two mean plasma levels similar to those found on exercise. 3. Significant bronchodilation and elevation of plasma glucose occurred with both infusion doses when compared with placebo. 4. Neither infusion caused a significant change in heart rate and only the higher dose caused a small but significant rise in systolic and fall in diastolic blood pressure. 5. Our results suggest that adrenaline as a hormone, at the levels found on exercise, is capable of causing bronchodilation and glycogenolysis in normal subjects. Its contribution to the cardiovascular response to exercise appears to be slight and suggests that its role in cardiovascular physiology may also be marginal.

Adult↗
PubMed1983

Effect of a 2 week course of oral salbutamol on adrenomedullary function in normal subjects.

1 The adrenal medullary response to intravenous histamine infusions (0.1 and 0.4 micrograms kg-1 min-1 histamine base) was studied in six normal subjects. 2 After a 2 week course of oral salbutamol (8 mg slow release twice daily) plasma adrenaline levels, thought to reflect adrenomedullary function, were unchanged both at rest and in response to histamine infusion. 3 The present study does not support our original hypothesis that salbutamol may be capable of suppressing the adrenal medulla in normal subjects.

Administration, Oral↗
PubMed1983

The effect of posture on the sympathoadrenal response to theophylline infusion.

We studied the effect of posture on the sympathoadrenal response to intravenous theophylline in six normal subjects. On three separate occasions they received an intravenous infusion of either theophylline (6 mg/kg) while supine, theophylline (6 mg/kg) while standing or saline as placebo while standing. With the subjects standing theophylline caused tremor, a peak heart rate of 99 +/- 6 beats/min, and an elevation of plasma cyclic AMP from 9.3 +/- 0.7 to 15.1 +/- 1.7 nmol/1 (mean +/- s.e. mean). There was a small, but significant, elevation of plasma adrenaline, noradrenaline and glucose. The elevation in plasma catecholamines was insufficient to explain either the sympathomimetic effects of theophylline or the rise in plasma cyclic AMP. Theophylline had little or no effect with the subjects supine. The mean peak theophylline concentration following infusion was significantly higher with the subjects upright than when supine (18.3 c.f. 12.4 mg/l, P less than 0.025). However, adequate plasma levels of theophylline were obtained in all subjects when lying or supine. Analysis of individual data suggests that differences in plasma levels of theophylline are unlikely to account for the increased effects seen on standing. The mechanism of action of theophylline cannot be explained by increased secretion of catecholamines alone. Theophylline appears to amplify the increased sympathetic activity associated with standing and this is probably by phosphodiesterase inhibition.

Adrenal Glands↗
PubMed1982

Blunted sympathoadrenal response to exercise in asthmatic subjects.

Six asthmatic subjects and six matched controls performed a standardized exercise test in which resting and post-exercise blood samples were assayed radioenzymatically for catecholamines. Plasma adrenaline one minute after exercise rose over threefold in the controls whereas in the asthmatic subjects there was no increase. Plasma noradrenaline increased to five times the basal concentration in the controls, but to less than half this level in the asthmatic subjects. These results agree with a recent study (Barnes et al. 1981) and suggest there is a marked abnormality of the sympathoadrenal response to exercise in asthmatic subjects.

Adult↗
PubMed1981

Use of computed tomography to demonstrate the extent of tuberculosis.

A group of 15 patients with tuberculosis was investigated by computed tomography to document the extent of the disease at the time of diagnosis. This was compared with information available from the clinical examination. Of the 33 sites of disease shown by CT (confined to the thorax and abdomen), only 17 had been demonstrated by clinical examination and chest x-ray. In addition, 7 patients had cervical lymphadenopathy (an area not scanned). CT shows tuberculosis to be more extensive than would be appreciated by conventional investigation. We think this argues against classifying the disease according to presenting anatomical site.

Humans↗
PubMed1981

Ultrastructure of hydrated proteoglycans using a pulsed plasma source.

During the past 10 years, attempts have been made to examine hydrated biological specimens by using wet chambers (at ambient temperature) [1-3] or cold stages (at -30 degrees C and below) during electron microscopic examination. Obtaining sufficient contrast of unstained hydrated biological samples has proven a considerable problem using both of these methods. Many fragile biological specimens, when examined hydrated, frozen or dried, are severely damaged by the electron beam and cannot be imaged by conventional scanning or transmission electron microscopy. In order to increase specimen contrast and eliminate electron beam induced trauma to the specimen, we have developed a wet-cell [4], which when used in concert with a pulsed plasma soft X-ray source, provides high contrast contact replicas of totally hydrated, unstained biological specimens. Although it has been postulated that hydrated unstained samples can be imaged by soft X-ray contact microscopy [5-7], to date there has been little success due to cell movement or degradation of the wet sample during the long exposure period necessary for an adequate imaging dose [8]. With the pulsed plasma source described in this study we have been able to use exposure times of approximately 40-60 ns while maintaining the sample in its hydrated state at atmospheric pressure. The resultant contact replicas exhibit good contrast and better than 30 nm spatial resolution when examined by conventional scanning electron microscopy.

Chemical Phenomena↗
PubMed1980

Imaging unstained proteoglycan aggregates by soft x-ray contact microscopy.

Soft X-ray contact microscopy is a relatively new form of ultrastructural imaging, having better than 6 nm resolution and being uniquely well suited for the examination of fragile, unstained biological specimens. The biological specimen placed on a layer of photoresist and exposed to soft X-rays (1-10 nm lambda) of a specific wavelength or broad band. After X-ray exposure, the specimen is removed from the photoresist and the latter chemically developed. When the developed replica is examined by high resolution scanning electron microscopy, the fine structure of the original biological specimen is faithfully reproduced. Since the soft X-ray replica is initially formed due to the differential absorption of the incident X-rays by the biological specimen, the resultant contact replica also reveals information about the elemental composition of the sample. This paper presents our application of this new technique for the study of the proteoglycans, the complex polyanionic macromolecules comprising the gel phase in the matrix of mammalian cartilage.

Animals↗
PubMed1980

Ultrastructural and elemental imaging of biological specimens by soft X-ray contact microscopy.

Soft X-ray contact microscopy offers a means of visualizing unstained as well as stained biological materials at better than 6 nm resolution. Unlike light and transmission electron microscopy, which rely on stains to increase specimen contrast, soft X-ray imaging is dependent upon the differential absorption of incident soft (1-10nm wavelength) X-rays by the endogenous elements within the specimen. The advantages of using soft X-rays for imaging are: 1) reduced specimen damage during exposure; 2) ability to image hydrated specimens at atmospheric pressure; 3) ability to image specimens ranging in thickness from less than 40 nm to as much as 10 microns; and 4) ability to map the elemental composition of the specimen through observation of the differential absorption of properly chosen incident x-ray wave lengths. This paper explains the principles of the image formation and demonstrates the use of soft X-ray contact microscopy with biological samples which could not readily be imaged in their natural form using conventional electron microscopy methods.

Animals↗
PubMed1979

Tetanus and diphtheria immunity in urban Minnesota adults.

Tetanus and diphtheria antitoxin levels were measured in 183 urban adults, using a hemagglutination technique. Protective levels (greater than 0.01 unit/mL) of tetanus antitoxin were present in more than 85% of sera from all subjects under 40 years of age and from men between 40 and 59 years old. A minority of women (36%) between 40 and 59 years of age, and of men (41%) and women (29%) over 60 years of age, were protected. Less than one quarter of the study group had protective levels (greater than 0.01 unit/mL) of diphtheria antitoxin. The results of the study suggest that a minority of middle-aged women and older adults have been appropriately immunized against diphtheria and tetanus.

Adolescent↗