Biomedical subjects
Publications and source records attributed to M Hall.
A case of small cell carcinoma of the lung presenting with acute pancreatitis is described. We believe this to be the first such case reported, despite the frequency of metastasis to the pancreas from such tumours. We discuss the investigation and management of such cases.
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We have developed and tested a rotational, mechanical approach to arterial plaque removal (PTRA or Percutaneous Transluminal Rotational Atherectomy). An elliptical burr is rotated by a helical driveshaft at 150,000 rpm. The tip of the burr is embedded with small diamond chips, 30 micron in diameter. Plaque is thus abraded and particles of 2-5 micron in diameter are released downstream. Preliminary studies in a rabbit model of iliac atherosclerosis showed a reduction in percent diameter stenosis from more than 80% to less than 40%. Perforations are the current principal complication, occurring in 2 of the 13 rabbit arteries. A second rotational catheter system has been developed for removal of fresh thrombus (PRT-Percutaneous Rotational Thrombectomy). Low speed rotation (5000 rpm) of a non-cutting catheter promotes the selective winding of fibrin with subsequent lysis of thrombus. This was effective in 20 out of 21 total thrombotic occlusions in a canine model of fresh clot, with a single perforation early in the experiment.
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The metabolism of benzo[a]pyrene (BP) by microsomal fractions of the skin, lungs and liver of the mouse, and the effects on this process of pretreatment with the xenobiotics phenobarbital (PB) and 3-methylcholanthrene (3-MC) were examined. Differences between the untreated tissues were found both in terms of the total amounts of diol recovered and in the relative proportions of the individual diols extracted following incubation. Induction with PB or 3-MC significantly altered the profiles of metabolic diols obtained with epidermal and hepatic microsomes compared with their respective controls. Pulmonary microsomes showed similar trends to those obtained with liver microsomes but these were not statistically significant. The optical purity of the BP-7,8-diol that was formed by each microsomal type was examined by direct resolution of the enantiomers on HPLC using a chiral stationary phase. In each case the (-)-7R,8R-enantiomer predominated. Pretreatment with 3-MC significantly decreased the optical purity of BP-7,8-diol recovered from incubations with skin microsomes, but significantly increased the optical purity of the diol extracted from incubations with lung and liver microsomes. In addition to the diols, an unidentified BP metabolite was found that eluted between BP-9,10- and 4,5-diol on a reverse-phase high-performance liquid chromatography (HPLC) system and which represented a major product in extracts of incubations of BP with both induced and uninduced skin and lung microsomal fractions.
Separate glomerular filtration rates were evaluated in 21 children with uni- or bilateral ureteropelvic junction stenosis, using the Tc-99m DTPA complex and the scintillation camera. The grade of alteration seen on urograms has influenced the surgeon in his decision to use a conservative or a surgical treatment, whereas the type of intervention (pyeloplasty or nephrectomy) was mainly based on the scintigraphic quantitation. The morphological data provided by an excretory urogram could not predict the degree of functional impairment. The scintigraphic evaluation of single kidney clearance was useful in the evaluation of the effects of medical and surgical treatment.
It has been shown that substance P(SP), as well as its carboxy and amino terminal fragments, affects a wide range of behaviors. In order to test the CNS activity of these fragments, we measured their effects on passive avoidance learning and monoamine activity. Following one-trial passive avoidance training, mice were injected intraventricularly with either a carboxy or amino terminal SP fragment (SP-C or SP-N), SP itself or phosphate-buffered saline (PBS). SP-N enhanced avoidance retention, which was tested 24 h after training. In a second experiment, monoamine activity was measured one hour after intraventricular injection of SP, PBS or SP fragments. SP-C decreased both nigral 5-hydroxyindoleacetic acid/5-hydroxytryptamine (5-HIAA/5-HT) and, to a lesser extent, 3,4-dihydroxyphenylacetic acid/dopamine, while SP-N increased nigral 5-HIAA/5-HT. It was concluded that SP-N and SP-C can exert behavioral and neurochemical effects that may be independent of the parent SP molecule.
Although several authors have claimed that the function of an obstructed kidney could be overestimated on Tc-99m DMSA imaging, the clinical importance of such an overestimation has not been well documented. Partial obstruction of one ureter was created in a rat, and a relative Tc-99m DMSA uptake was obtained 4 hours after intravenous injection. By puncture of the isolated obstructed kidney, it was shown that the function of that kidney was overestimated by at least 17%.
By means of semi-structured interviews, this study investigates the work experience of 13 lesbians employed by large corporations. The respondents, who were already discredited for being women, had to manage the further potentially discrediting information of their lesbianism. The author examines the strategies used to manage such information. Because these strategies frequently included deception, the respondents then had to design a series of counter-strategies to avoid seeing themselves as dishonest. Each woman's strategy was unique; nevertheless, certain perceptions and approaches were common to all the respondents.
Healthcare organizations are finding it advantageous, and in some cases necessary, to join together to offer new services, seek economies of scale, or just stay in business. These partnerships can take various forms including joint ventures, shared service agreements, or multiprovider arrangements. together, they represent new approaches to operating more efficiently and effectively in a changing healthcare industry. This article marks the beginning of a three-part series on the joint venture in health care. The series explores possible joint venture models, explains the legal implications in setting up a joint venture, and shows how to evaluate a potential deal. Together they provide a background and a starting point for the financial manager considering the possibility of a joint venture.
Many times, healthcare joint ventures are considered second class, sideline businesses, and consequently, are not viewed as complex business relationships. However, compared to other small enterprises, the joint venture presents a complex list of legal and practical issues that must be understood and resolved. Such issues as organizational form, antitrust, reimbursement, licensing, and securities laws must be considered to ensure a successful joint venture.
To be successful, a hospital-physician joint venture must be guided by a strategy that includes a coherent business strategy, an orientation to the specific needs of the potential physician participants, a bias towards closure, and a rigorous process for evaluating, structuring, and implementing transactions. This article focuses on the last characteristic of the strategy--a process for evaluation, structuring, and implementation. Such a process will establish the basic viability of the project, give direction to the approach, provide a fundamental understanding of the transaction, and create an overall businesslike attitude.
There is increased emphasis nowadays on the role of the general practitioner in preventive care for children. Accordingly, an analysis of the child's perception of the doctor and of the factors which influence and mould that perception are important. In New Zealand children's paintings have been used for such analyses. The present study looked at children's paintings of their family doctors in a Devonshire village. The findings show that boys are more likely than girls to depict their doctors as a gruesome or threatening character, and suggest that medical contact has little, if any, influence on character portrayal of doctors. Other factors that might influence character portrayal and are now thought worthy of detailed study, include television viewing patterns, personality, age, home background and artistic ability.
Incubation of rat adipocytes with the same range of noradrenaline concentrations that stimulate lipolysis caused a rapid and stable decrease in the activity of fatty acyl-CoA synthetase. Corticotropin, glucagon and dibutyryl cyclic AMP also decreased the activity of the enzyme. The effect of noradrenaline was apparent over a wide range of concentrations for the three substrates of the enzyme. A novel fluorescence assay of fatty acyl-CoA synthetase using (1,N6-etheno)-CoA is described. The effect of noradrenaline was not abolished by inclusion of albumin in homogenization buffers, persisted through subcellular fractionation and isolation of microsomes (microsomal fractions) and even survived treatment of microsomes with Triton X-100. The effect of noradrenaline was rapidly reversed within cells by the subsequent addition of insulin or propranolol. The inclusion of fluoride in homogenization buffers did not alter the observed effect of noradrenaline. Additions of cyclic AMP-dependent protein kinase to adipocyte microsomes caused considerable phosphorylation of microsomal protein by [gamma-32P]ATP, but did not affect the activity of fatty acyl-CoA synthetase.
Incubation of rat adipocytes with the phorbol ester TPA caused a dose-dependent, persistent increase in phosphatidate phosphohydrolase activity and decrease in fatty acyl-CoA synthetase activity. Half-maximal effects were obtained with 1-2 X 10(-10) M TPA. TPA did not alter basal or noradrenaline-stimulated lipolysis. It is suggested that these two enzymes might be modified by protein kinase C.
A variety of agents can induce mammalian tumor cell lines to acquire characteristics of the normal cell counterpart. Dimethylsulfoxide (DMSO) has been an effective differentiating agent in many tumor cell lines. In the present study a Dunning rat prostate tumor subline, MAT LyLu, available as an in vitro continuous cell culture was treated with 2.25% DMSO (vol/vol). Treated MAT LyLu cells had a decreased growth rate, saturation density, and clonogenicity, an increased doubling time, and alterations in enzyme activity and tumorigenicity when compared to untreated MAT LyLu cells. The cell viability of treated cells at the saturation density was greater than 90%. MAT LyLu cells treated with DMSO and then removed from DMSO (posttreated) when compared to untreated cells had similar growth rates, doubling times, clonogenicities, enzyme activities, and tumorigenicities. Posttreated MAT LyLu cells had a different growth pattern than untreated MAT LyLu cells. Posttreated cell viability at saturation density was greater than 90%. This investigation demonstrated that a rat prostate adenocarcinoma grown in medium containing 2.25% DMSO acquired characteristics consistent with differentiated prostate cells. Posttreated MAT LyLu cells were similar in many characteristics to untreated cells but were not identical. The alterations noted were not cytotoxic and were not completely reversible. The results of this study correlated with the observations of other investigators who have studied mammalian tumor cell lines exposed to DMSO.
Urine was cultured from 441 healthy children, aged 3 to 36 months, simultaneously by standard pour plating and by dip-slide. Significant bacteriuria (greater than or equal to 10(5) colony-forming units/ml in two successive specimens) was found in 13 children (2.9%): 11 boys, 2 girls. Proteus mirabilis was the most frequently isolated organism. Of the 13 infants, 2 had malformations on intravenous pyelography. All 13 had a negative antibody-coated bacteria test. Nitrite test (N-Multistix) and microscopic examination were also performed. The results suggest that asymptomatic bacteriuria cannot be accurately predicted either by microscopic examination or by the nitrite test, and that the quantitative urine culture by dip-slide is the easiest and most reliable way of diagnosing urinary tract infections. However the criteria of Kass were found to be too strict.