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Biomedical subjects

R Hawkins

Publications and source records attributed to R Hawkins.

At least 91 records · Page 5Linked to original sources
PubMed1990

An unusual case of variegate porphyria with possible homozygous inheritance.

We report an unusual case of variegate porphyria in a young girl with epilepsy, mental retardation and premature adrenarche. Symptoms of porphyria commenced about the age of 12 years and death occurred about 18 months later. The patient had very low protoporphyrinogen oxidase activity in her cultured fibroblasts. Both parents had half the normal activity of this enzyme in lymphocytes and are heterozygous for the abnormal gene for variegate porphyria. Therefore, it is possible that the patient was a homozygous variant. Anticonvulsant therapy and low hepatic 5 alpha reductase activity were probably other contributing factors to the severity of the condition in this patient.

Animals↗
PubMed1989

Respiratory symptoms, lung function, and sensitisation to flour in a British bakery.

A survey of dust exposure, respiratory symptoms, lung function, and response to skin prick tests was conducted in a modern British bakery. Of the 318 bakery employees, 279 (88%) took part. Jobs were ranked from 0 to 10 by perceived dustiness and this ranking correlated well with total dust concentration measured in 79 personal dust samples. Nine samples had concentrations greater than 10 mg/m3, the exposure limit for nuisance dust. All participants completed a self administered questionnaire on symptoms and their relation to work. FEV1 and FVC were measured by a dry wedge spirometer and bronchial reactivity to methacholine was estimated. Skin prick tests were performed with three common allergens and with 11 allergens likely to be found in bakery dust, including mites and moulds. Of the participants in the main exposure group, 35% reported chest symptoms which in 13% were work related. The corresponding figures for nasal symptoms were 38% and 19%. Symptoms, lung function, bronchial reactivity, and response to skin prick tests were related to current or past exposure to dust using logistic or linear regression analysis as appropriate. Exposure rank was significantly associated with most of the response variables studied. The study shows that respiratory symptoms and sensitisation are common, even in a modern bakery.

Adult↗
PubMed1989

Lack of clinical benefit after treatment of systemic sclerosis with total lymphoid irradiation.

Six patients with systemic sclerosis and internal organ involvement were randomized to receive total lymphoid irradiation (TLI) or to serve as untreated controls. Despite evidence of profound immunosuppression, we were unable to detect any longlasting clinical benefit in the treated patients, with follow-ups ranging from 1-4 years after TLI. Moreover, the results suggest that this therapy may accelerate pulmonary and gastrointestinal deterioration in scleroderma.

Adult↗
PubMed1988

Gastric emptying of mixed solid-liquid meal in patients with intestinal pseudoobstruction.

Gastric emptying of solids and liquids was evaluated simultaneously in 11 patients with intestinal pseudoobstruction. Despite a normal upper gastrointestinal series in most patients, over two thirds of the patients had abnormal gastric emptying of solids and/or liquids. Half these patients exhibited delayed emptying of solids and accelerated emptying of liquids. Alterations in motility patterns were observed in the four patients tested including decreased frequency or absence of migrating motor complexes originating in the stomach, shortening or absence of phase I, and loss of distinct fasted and fed patterns. Both basal values and mean postprandial increments in serum gastrin concentrations were lower in the patients, whereas no significant difference was found for pancreatic polypeptide concentrations when compared to normals. Our findings emphasize the functional heterogeneity of patients with intestinal pseudoobstruction. In addition, in contrast to previous reports which used barium meals to access gastric function, we observed a high prevalence of gastric emptying disturbances in these patients, suggesting that the motility disturbance is not restricted to the small intestine.

Adult↗
PubMed1988

The utility of SPECT liver-spleen imaging in the evaluation of a possible accessory spleen.

A case where an x-ray CT examination showed the existence of an unidentified perisplenic mass is presented. This mass was determined to be an accessory spleen after an evaluation with Tc-99m labeled sulfur colloid. This report describes a clinical indication for the use of SPECT imaging of a patient when a mass of uncertain significance is discovered.

Abdominal Neoplasms↗
PubMed1987

Hepatorenal syndrome. Studies of the effect of vascular volume and intraperitoneal pressure on renal and hepatic function.

Eleven patients with well-documented hepatorenal syndrome were studied by measurement of blood volume, glomerular filtration rate, renal plasma flow, plasma aldosterone concentration, renin substrate concentration, and plasma renin activity. They were then given 750 ml of stored plasma, 750 ml of fresh frozen plasma, and then an infusion of angiotensin II, in random order on successive days. Infusion of fresh frozen plasma improved function more than did stored plasma and in addition returned a very low filtration fraction toward normal. Angiotensin II infusion increased filtration fraction, but decreased glomerular filtration rate, renal plasma flow, and urine flow sharply. Patients were then given a daily infusion of 1,000 ml of fresh frozen plasma for seven to 18 days to expand the blood volume to supranormal levels as assayed by serial measurement of blood volume. Plasma aldosterone levels decreased to a normal range, glomerular filtration rate and renal plasma flow both increased, and urinary excretion of sodium and potassium both returned toward normal. The effect of intraperitoneal pressure was then studied by measuring glomerular filtration rate, renal plasma flow, pressure in the vena cava, hepatic vein free flow, and hepatic vein wedged pressure before, during, and after paracentesis to reduce the intraperitoneal pressure from 30 to 40 cm H2O to 12 to 17 cm H2O. Venous pressures moved parallel to ascitic fluid pressures, and glomerular filtration rate, renal plasma flow, and urine flow all improved sharply; then, as ascitic fluid continued to form, reducing vascular volume, urine flow, glomerular filtration rate, and renal plasma flow all decreased slowly. Six patients then underwent placement of a LeVeen shunt. Improvement in glomerular filtration rate and renal plasma flow and clinical condition was dramatic. During postoperative observation of up to two years, progressive improvement in hepatic function has occurred.

Angiotensin II↗
PubMed1987

Outcome of asthma induced by isocyanates.

Isocyanates are widely used in industry for the manufacture of polyurethanes. Although they are recognized as an important cause of occupational asthma, it is unclear whether asthma persists after avoidance of exposure. We have followed up 50 cases, all of whom had avoided exposure for at least 4 years. At follow-up, 82% continued to have respiratory symptoms and approximately half of these required treatment at least once per week. These results indicate that a significant proportion of those with isocyanate-induced asthma are likely to have persisting symptoms for at least several years after exposure is avoided.

Adult↗
PubMed1987

The temporal relationship between increases in airway responsiveness to histamine and late asthmatic responses induced by occupational agents.

The temporal relationship between increases in airway responsiveness and the late asthmatic response was assessed in nine patients challenged with occupational agents toluene diisocyanate (one patient), carmine (one patient), maleic anhydride (two patients), colophony (four patients), and trimellitic anhydride (one patient). The provocation concentration of histamine causing a 20% decrease in FEV1 (PC20) was measured before challenge and at approximately 3 hours and 24 hours on control and active-challenge days. Thirteen active challenges provoked eight definite late asthmatic responses (maximum fall in FEV1 greater than 15% at 3 to 11 hours). At 3 hours after the challenges that provoked late responses, there was a significant (p less than 0.02) decrease in PC20 that was more (p less than 0.03) than that observed for the five tests provoking early (late FEV1 fall 0% to 5%) or equivocal late (FEV1 fall 6% to 15%) responses. At 24 hours, PC20 remained decreased (p less than 0.05), although it was less so than at 3 hours (p less than 0.05) and not significantly when compared with challenge tests causing single early or equivocal late responses. The 3-hour decreases in PC20 were identified when FEV1 (five of seven observations) was greater than 90% of prechallenge values. For the nine independent tests, the 3-hour decreases in PC20 correlated (r = 0.72; p less than 0.05) with the magnitude of the late falls in FEV1, whereas this was not observed at 24 hours (r = 0.35; p, not significant).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1987

Mortality response and LC50 values for juvenile and adult crayfish, Procambarus clarkii exposed to Thiodan (insecticide), Treflan, MSMA, Oust (herbicides) and Cutrine-Plus (algicide).

Toxicities of three herbicides (Treflan, MSMA and Oust), an algicide (Cutrine-plus) and an insecticide (Thiodan) to juvenile (3.0-3.4 cm) and adult (9.0-10.0 cm) crayfish, Procambarus clarkii, were determined by 96 h static bioassays. Freshly prepared 0.01% and 1.0% aqueous stock solutions of these pesticides were diluted to desired concentrations. Mortalities were recorded each day up to 96 h. Aged tap-water was used for preparing all test solutions. Per cent mortalities were analyzed for linear regression and LC(50) values were computed by probit analysis. LC(50) values for juvenile P.clarkii in the descending order of toxicity were: 24 ppb Thiodan, 13 ppm Treflan, 101 ppm MSMA, 461 ppm Cutrine-plus, 12,174 ppm Oust; and for adults these values were: 423 ppb Thiodan, 26 ppm Treflan, 1019 ppm MSMA and 2945 ppm Cutrine-plus. No LC(50) values for adult crayfish could be computed for Oust herbicide which caused no mortalities up to 60,000 ppm concentration. Comparing the overall toxicities of these pesticides, Thiodan was the most toxic to all crayfish; followed by Treflan, MSMA, Cutrine-plus and Oust. Oust was more than 1/2 million times less toxic than Thiodan to juvenile crayfish. Published LC(50) values indicate that freshwater crayfish are more tolerant than marine decapods, Crangon septemspinosa and Mysidopsis bahia, to Thiodan insecticide and Treflan herbicide.

Journal Article↗
PubMed1986

Studies on the permeability of the blood-brain barrier in experimental diabetes.

Whether the increased capillary permeability characteristic of diabetes extends to the blood-brain barrier is presently unclear. We have examined in streptozotocin-diabetic rats the permeability of the blood-brain barrier at the level of 12 discrete brain regions employing 3 intravenous tracers of different molecular weight: sucrose, insulin and horseradish peroxidase. In animals killed 5 min after tracer injection both the sucrose and the inulin spaces were similar to controls. In order to assess whether more prolonged circulation of tracers would uncover leakage, we studied brain spaces at longer intervals after tracer injections. When inulin was allowed to circulate for 15 min prior to killing, animals with 4 weeks of diabetes (but not 2 weeks) exhibited larger inulin spaces at the level of the medio-basal hypothalamus (p less than 0.01), medio-dorsal hypothalamus (p less than 0.05) and periaqueductal gray (p less than 0.01). Horseradish peroxidase, even after 75 min of perfusion, remained confined in both diabetic and control animals to central nervous system areas devoid of blood-brain barrier. Thus, after a relatively short duration of diabetes the blood-brain barrier manifests an increased permeability. It is subtle, limited to some brain regions and selective for low molecular weight tracers.

Animals↗
PubMed1986

Dominantly inherited cardioskeletal myopathy with lysosomal glycogen storage and normal acid maltase levels.

A family is presented in which 7 members over 3 generations were affected by cardioskeletal myopathy. A vacuolar myopathy with excessive free and intralysosomal glycogen storage in skeletal and cardiac striated muscle was identified in biopsy studies. Post-mortem studies in several patients revealed changes of a congestive cardiomyopathy with myocardial fibrosis. Acid maltase, phosphorylase, debrancher and lysosomal enzyme screens, and glycolytic enzyme levels in skeletal muscle, were normal in 1 case. This is the third report of non-acid maltase deficient lysosomal glycogen storage disease and adds to previous reports with the presentation of detailed family studies, examined of ante- and post-mortem cardiac histology and reports of detailed glycolytic and lysosomal enzyme analysis. This syndrome is unusual among glycogenoses in having a dominant inheritance pattern.

Adult↗
PubMed1986

Epstein-Barr virus infection and immunity in bone marrow transplant recipients.

Studies on patients for up to one year following allogeneic, HLA-matched bone marrow transplants have shown no increased incidence of salivary Epstein-Barr (EB) virus secretion and no significant rise in EB-virus-specific antibody titers. EB-virus-specific cytotoxic T cells could be detected in the peripheral blood of all patients by six months posttransplant. For up to one year posttransplantation in vitro EB virus infection of peripheral blood B lymphocytes from the majority of patients leads to an abortive infection followed by cell death, and without the establishment of continuously growing cell lines. This abnormality appeared to be due to patients' monocytes, which formed a defective feeder cell layer in culture, and it could be circumvented by culturing the EB-virus-infected B cells from patients on a feeder layer of x-irradiated adherent cells from normal peripheral blood. These findings may explain the relative lack of EB-virus-associated lymphoma seen in bone marrow transplant recipients when compared with other groups of transplant patients.

Adolescent↗
PubMed1985

Interaction of smoking and atopy in producing specific IgE antibody against a hapten protein conjugate.

A survey was carried out of a population of workers exposed to tetrachlorophthalic anhydride, an acid anhydride epoxy resin curing agent known to cause asthma. Using a radioallergosorbent test with a tetrachlorophthalic anhydride human serum albumin conjugate, specific IgE antibody was detected in serum from 24 out of 300 factory floor workers exposed to tetrachlorophthalic anhydride. Of these 24, 20 (83.3%) were current smokers compared with 133 (48.2%) of 276 without antibody (p less than 0.01), and there was a weaker association with atopy, defined by skin tests with common allergens. Smoking and atopy interacted, the prevalence of antibody being 16.1% in atopic smokers, 11.7% in non-atopic smokers, 8.3% in atopic non-smokers, and nil in non-atopic non-smokers (p less than 0.025). Smoking may predispose to, and interact with atopy in, the production of specific IgE antibody to this hapten protein conjugate.

Adult↗
PubMed1985

A longitudinal study of possible allergy to enzyme detergents.

One hundred and thirty-six subjects with asthma and/or hay fever were surveyed for possible sensitization to the Bacillus licheniformis protease present in the commercial antigenically identical enzymes (Alcalase and Maxatase) used in household detergents. Prick-test reactions reported as minimally positive were given by one subject to both commercial enzyme preparations at the same standard non-irritating concentrations and by four others to one but not the other antigenically identical enzyme. Two of the five, and an additional seven, gave weak prick tests to the purified enzyme (Koch-Light Protease) at test protein concentrations 100 times stronger and to which non-specific irritation occurs. The findings are strongly against interpretation of these reactions as positive and were on no occasion comparable with those in sensitive workers. The skin-test reactions are attributable to non-specific effects. Neither enzyme-specific RAST IgE tests nor clinical histories suggested clinical sensitivity. Enzyme-specific RAST IgE for eighty-eight subjects over a period of 5 years showed no correlation with exposure. None had developed specific IgE levels like those of sensitized workers, and their RAST levels did not differ significantly from cord blood, unexposed subjects and prick-test-negative workers. The eight with the largest increase in specific IgE were prick-test-negative and their clinical reactions to enzyme detergents were comparable to those of non-enzyme detergents. There is no evidence from this study that exposure to modern, non-dusty household enzyme-containing detergents is likely to lead to clinical sensitization.

Adult↗