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Biomedical subjects

A Jenkins

Publications and source records attributed to A Jenkins.

At least 145 records · Page 8Linked to original sources
PubMed1983

PTH and vitamin D responses during treatment of hypomagnesaemic hypoparathyroidism.

The response of calcium regulating hormones in a patient with hypomagnesaemic hypoparathyroidism was assessed during magnesium infusion. Magnesium repletion was accompanied by prompt restoration of PTH secretion which subsequently stimulated 1,25-diOHD3 production, thus correcting hypocalcaemia. Further, failure of the patient to respond to previous 1 alpha-OHD3 therapy suggests that severe magnesium depletion may also result in a state of acquired resistance to the active metabolites of vitamin D.

Calcifediol↗
PubMed1982

Effect of processing on digestibility and the blood glucose response: a study of lentils.

To test the effect of processing on digestibility and the glycemic response to a leguminous seed, a group of eight healthy volunteers took a series of breakfast test meals containing either lentils which had been processed in four different ways or the same amount of carbohydrate as white bread. Lentils, boiled for 20 min, resulted in a flattened blood glucose response by comparison with bread. This was unaltered by blending the lentils to a paste or boiling them for an additional 40 minutes. However the blood glucose response was significantly enhanced by drying the boiled blended lentils for 12 h at 250 degrees F. In vitro digestion with human saliva showed the rate of sugars released from the food related positively to the blood glucose rise. Breath hydrogen studies indicated that carbohydrate malabsorption was too small to account for differences in the blood glucose response. These results emphasize the importance of processing in determining digestibility and hence the glycemic response to a food.

Blood Glucose↗
PubMed1982

The effect of fermented and unfermented milks on serum cholesterol.

Groups of 10 to 13 healthy volunteers were provided with 11 supplements of 2% butterfat milk (2% milk), whole milk, skim milk, yogurt, buttermilk, and sweet acidophilus milk daily for a 3-wk period. Despite increases in caloric intakes on all supplements, no significant increases were found in total, low-density, and high-density lipoprotein cholesterol. A significant weight gain was seen in subjects taking yogurt and acidophilus groups; these were the only two groups showing significant rises in triglyceride levels. These results in normal volunteers focus attention on the current practice of recommending only skim or 2% milk for hyperlipidemic individuals.

Adolescent↗
PubMed1982

Generation of fecal and total coliform surges by stream flow manipulation in the absence of normal hydrometeorological stimuli.

The response of Escherichia coli and total coliform concentration to increases in river discharge was investigated. Artificial hydrographs were generated on eight occasions between 21 October 1979 and 3 March 1981 by releasing water from Thruscross Reservoir in North Yorkshire into Fewston Reservoir. The majority of the releases were made after rainless periods to isolate the effects of stream channel entrainment from those induced by rainfall on the land surface. In the absence of rainfall, bacterial concentrations are shown to increase more than 10-fold in response to stage increases. It is suggested that two stores of bacteria must exist on the catchment, the first being a land store and the second a channel or near-channel store. Movement from the land to the channel store must relate to hill slope hydrological processes, whereas movement between stores in the channel fluvial system may be closely allied to sedimentary processes. Some consideration is given to bacterial levels in relation to European Economic Communities guidelines for contact recreation.

England↗
PubMed1978

Cigarette smoking among secondary schoolchildren in 1975. Prevalence of respiratory symptoms, knowledge of health hazards, and attitudes to smoking and health.

A questionnaire relating to smoking habits, respirator symptoms, and health attitudes was administered to 10 498 secondary schoolchildren in 1975. The results reported in this paper indicate that children who smoke regularly have a higher prevalence of upper respiratory tract infections and a higher incidence of the respiratory symptoms, cough, phlegm production with a cold, and shortness of breath, compared with non-smokers. Children are aware of the risks of lung cancer when smoking, but less aware of the other more immediate health risks, and this is particularly so in the younger age groups. It is suggested that health education should be directed towards younger children and that more use should be made of the fact that smoking clearly makes them less healthy.

Adolescent↗
PubMed1976

A mammalian nicking endonuclease.

Purification and properties are described for an endonuclease isolated from calf thymus which attacks double-stranded, unmodified DNA, primarily by making single-strand breaks. No detectable acid-soluble products arise from the reaction. Double-strand breaks may occasionally be produced by the introduction of single-strand breaks on opposite strands in close proximity. The enzyme does not attack denatured DNA and is not inhibited by tRNA. Although added divalent cations are not required for activity, the enzyme is inhibited by EDTA, which suggests an essential role for bound cations; reaction is inhibited by Ca2+. The endonuclease has a broad pH optimum and is inactivated by preincubation at temperatures of 45 degrees C and higher. The molecular weight as determined by gel chromatography is about 30 000. Analysis of the products of reaction on a defined substrate, bacteriophage T3 DNA, by sedimentation in alkaline sucrose density gradients indicates limit products with chain lengths of about 0.8 X 10(6) daltons. On electrophoresis in agarose gels these products were shown to be heterogeneous in size. The endonuclease appears to generate 3'-hydroxyl and 5'-phosphate ends. The ability of the endonuclease to utilize bovine DNA as substrate argues against a restriction role for this enzyme.

Animals↗
PubMed1976

Repair of ultraviolet light-induced damage in Micrococcus radiophilus, an extremely resistant microorganism.

Repair of ultraviolet radiation damage was examined in an extremely radioresistant organism, Micrococcus radiophilus. Measurement of the number of thymine-containing dimers formed as a function of ultraviolet dose suggests that the ability of this organism to withstand high doses of ultraviolet radiation (20,000 ergs/mm2) is not related to protective screening by pigments. M. radiophilus carries out a rapid excision of thymine dimers at doses of ultraviolet light up to 10,000 ergs/mm2. Synthesis of deoxyribonucleic acid is reduced after irradiation, but after removal of photodamage the rate approaches that in unirradiated cells. A comparison is drawn with Micrococcus luteus and M. radiodurans. We conclude that the extremely high resistance to ultraviolet irradiation in M. radiophilus is at least partly due to the presence of an efficient excision repair system.

Cell-Free System↗
PubMedDate not supplied

Flatulent dyspepsia: a tiered symptom complex?

The symptom complex of flatulent dyspepsia is ill-defined but is made up of at least nine individual symptoms. The relationship between these symptoms is not known and thier change after cholecystectomy in gall-stone patients is unpredictable; they disappear completely in less than half the patients. We studied the symptoms in one hundred and thirty nine patients, using various computer programmes to see if the changes after operation could be predicted and if some of the symptoms were linked or formed "clusters". The results did not show any standard relationship between the symptoms. We have therefore, proposed the hypothesis of a tiered symptom complex to explain these observations. They could be produced by a motility disorder affecting different parts of the gastro-intestinal tract to a varying degree.

Cholecystectomy↗
PubMedDate not supplied

Digital mapping of multi-parameter contrast functions in magnetic resonance (MR) imaging using a standard MR computer system and digital display.

A technique is described which utilises the full analysis and display capabilities of a commercial MRI system to produce digital maps of multi-parameter functions produced by MR contrast theory. The technique is utilised to determine the effects of nominating specific overall scan times on the optimum solutions as produced by the theory and it is shown that different solutions are obtained when the theory is applied using typical clinical constraints. The digital mapping approach is potentially of great value in prospectively determining pulse timing parameters to produce optimum contrast images, in producing contrast maps to aid retrospective image interpretation, and as a training aid for clinicians inexperienced in the interpretation MR images.

Computer Graphics↗
PubMedDate not supplied

The use of in vitro magnetic resonance tissue studies to optimise pulse sequences in the imaging of intracranial haemorrhage.

The choice of appropriate MR pulse sequences to highlight a particular pathology to best advantage is not always straightforward. In this study of intracranial haemorrhage, tissue relaxation times measured in vitro were entered into a computer program which calculated the signal intensity of each tissue (brain, blood, CSF, and bloody CSF) for all possible echo (TE) and repeat (TR) times. Analysis of graph plots of the results enabled the selection of pulse sequences which gave optimal separation of the signal intensities of intracranial haemorrhage from those of normal intracranial contents. The sequences thus chosen were used successfully in the imaging of patients with intracranial haemorrhage.

Cerebral Hemorrhage↗
PubMedDate not supplied

Assessment of the acuteness of heroin deaths from the analysis of multiple blood specimens.

Data was compiled from 126 morphine-involved cases investigated by the Office of the Chief Medical Examiner, State of Maryland, USA. An investigation was conducted into whether comparison of morphine concentrations from a central and peripheral site could be used to determine whether a morphine death was acute or delayed. Fifty cases were identified as 'acute' because the urine free morphine concentration by radioimmunoassay (RIA) was less than 25 ng/mL; 76 cases were classified as 'random' because they had a urine morphine concentration greater than 25 ng/mL by RIA. The average heart blood to peripheral blood morphine concentration ratio in the acute deaths was 1.40. The average heart blood to peripheral blood morphine concentration ratio in the random deaths was 1.18. Because there was considerable overlap between the two groups of data, the authors conclude that it was not possible to predict 'acute' opiate intoxication deaths versus 'delayed' deaths when the only information available is heart and peripheral blood free morphine concentrations.

Drug Overdose↗
PubMedDate not supplied

Perphenazine distribution in a postmortem case.

The case of a 34-year-old, mentally challenged, Caucasian female found dead in a group home is presented. Empty containers of perphenazine and valproic acid were found next to her bed. The perphenazine had been prescribed to another patient. No anatomic cause of death was determined at autopsy. Comprehensive testing of the heart blood for ethanol and drugs identified perphenazine at a concentration of 4.4 mg/L and valproic acid at a concentration of 950 mg/L. The distribution of perphenazine in other specimens was consistent with previously reported phenothiazine cases. The medical examiner ruled that the cause of death in this case was multiple drug intoxication and the manner of death was suicide.

Adult↗
PubMedDate not supplied

A quantitative index of ventricular and extraventricular intracranial CSF volumes using MR imaging.

A new technique is described that utilises a novel magnetic resonance pulse sequence to produce a quantitative index both for ventricular and, for the first time, extraventricular intracranial CSF volumes. The pulse sequence is a combination of a null-point inversion recovery sequence with an extended spin-echo read (echo time = 400 ms), which produces a contrast of CSF to white or grey matter of approximately 120:1. A series of experiments are performed on phantoms representing CSF filled ventricles and sulci over a wide range of volume values, and it is found that the standard deviation of differences between true and estimated values is 3.9% for ventricles, 4.6% for total cranial CSF, and 7.9% for CSF within the sulci. Normal volunteer reproducibility studies revealed corresponding standard deviations of less than 5.5%. Using the technique to produce absolute estimates of CSF volumes in normal subjects and patients produced results in good agreement with previously published necropsy studies. The technique has wide neurological and neurosurgical applicability particularly in terms of differential diagnosis and as an objective monitor of therapy or progression in conditions such as hydrocephalus, atrophy, and benign intracranial hypertension.

Adolescent↗
PubMedDate not supplied

MR relaxation times of cerebrospinal fluid.

A review of 15 recent publications purporting to provide the relaxation times of CSF reveals a considerable disparity in the quoted results, by a factor of five in terms of T1 (range 1,000 to 5,500 ms) and by a factor of 16 for T2 (range 166 to 2,640 ms). In this article measurements are performed independently on both a spectrometer and an imager. The results indicate that for CSF T1 is greater than 3,000 ms and T2 is approximately 2,000 ms at 6 MHz. The vast differences in relaxation behaviour between CSF and other body tissues have considerable clinical implications and present profound diagnostic opportunities. The application of this knowledge to ventriculography, myelography, and image contrast methodology is discussed.

Cerebrospinal Fluid↗
PubMedDate not supplied

Experimental intracerebral haematoma in the rat: sequential light microscopical changes.

In a small animal model of controlled intracerebral haemorrhage, changes within the haematoma and surrounding tissues were examined by light microscopy in toluidine blue stained semithin sections. Groups of animals were killed at 2, 6, 15, 24 and 48 hours, 2, 4, 8 and 14 days, and 3 months survival. Sequential changes in neurons, glia and leucocytes, together with the gradual absorption of the blood clot and its replacement by an astrocytic scar are described.

Animals↗