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Biomedical subjects

J Alexander

Publications and source records attributed to J Alexander.

At least 325 records · Page 18Linked to original sources
PubMed1993

Comparison of diabetic retinopathy detection by clinical examinations and photograph gradings. Barbados (West Indies) Eye Study Group.

OBJECTIVE: To compare the use of clinical examination and fundus photograph gradings in detecting diabetic retinopathy in a population that includes persons with and without diabetes. DESIGN: Population-based epidemiologic study. SETTING: Sir Winston Scott Polyclinic, Bridgetown, Barbados, West Indies. PARTICIPANTS: Subset of a random sample of the country's population aged 40 to 86 years. RESULTS: Among 1168 black persons with fundus photograph evaluations, ophthalmologic examinations, diabetes history, and glycated hemoglobin data, 21% reported a history of diabetes; 9.5% had definite diabetes (glycated hemoglobin > 11.5%); and 13.3% had a diabetes history and glycated hemoglobin value less than or equal to 11.5%. The frequency of diabetic retinopathy in this group was 7.7% (90/1168) by clinical examination, 8.7% (102/1168) by photograph gradings, and 6.7% (78/1168) by both methods. CONCLUSIONS: These results suggest that in certain populations that include diabetics and nondiabetics, a clinical examination by an ophthalmologist will detect most cases of diabetic retinopathy identified by disc and macula photographs read by skilled graders. However, it will lead to an underestimate of prevalence. Staff availability and cost, issues not examined in this study, should determine which approach is selected.

Adult↗
PubMed1993

Response to added dead space in ventilated preterm neonates and outcome of trial of extubation.

The ventilatory response to an added external dead space was assessed in preterm babies, recovering from respiratory distress syndrome, immediately prior to extubation. All babies were ready for extubation as defined by routine clinical criteria. Baseline measurements of respiratory rate, tidal volume, and minute ventilation were made over a 2 min period using a computerized system consisting of a pneumotachometer connected directly to the proximal end of the endotracheal tube. The measurements were repeated after addition of an external dead space equivalent to 2 anatomical dead spaces (4.4 mL/kg body weight). Thirty-four babies were studied on 40 occasions. Twenty-four infants (60%) were successfully extubated and 16 (40%) required reintubation. Infants in the success and failure groups were matched for gestation at birth, postconceptional age and weight at the time of study, maximum ventilatory requirements, and treatment with methylxanthines. The added external dead space resulted in an increase in minute ventilation in 38 out of the 40 studies. Extubation success and failure groups were compared by expressing the minute ventilation after addition of the external dead space as a percentage of the baseline minute ventilation (%MV1). Successful extubation was associated with a higher median %MV1 compared with babies who failed extubation (156; range, 89.3 to 230; compared to 131; range, 75.2 to 165; P = 0.006). This test may be useful in deciding which babies could be successfully extubated.

Humans↗
PubMed1993

Glycyrrhizic acid in liquorice--evaluation of health hazard.

Literature on case reports, clinical studies and biochemical mechanisms of the sweet-tasting compound glycyrrhizic acid in liquorice was critically reviewed to provide a safety assessment of its presence in liquorice sweets. A high intake of liquorice can cause hypermineralocorticoidism with sodium retention and potassium loss, oedema, increased blood pressure and depression of the renin-angiotensin-aldosterone system. As a consequence, a number of other clinical symptoms have also been observed. Glycyrrhizic acid is hydrolysed in the intestine to the pharmacologically active compound glycyrrhetic acid, which inhibits the enzyme 11 beta-hydroxysteroid dehydrogenase (in the direction of cortisol to cortisone) as well as some other enzymes involved in the metabolism of corticosteroids. Inhibition of 11 beta-hydroxysteroid dehydrogenase leads to increased cortisol levels in the kidneys and in other mineralocorticoid-selective tissues. Since cortisol, which occurs in much larger amounts than aldosterone, binds with the same affinity as aldosterone to the mineralocorticoid receptor, the result is a hypermineralocorticoid effect of cortisol. The inhibitory effect on 11 beta-hydroxysteroid dehydrogenase is reversible; however, the compensatory physiological mechanisms following hypermineralocorticoidism (e.g. depression of the renin-angiotensin system) may last several months. It is not possible, on the basis of existing data, to determine precisely the minimum level of glycyrrhizic acid required to produce the described symptoms. There is apparently a great individual variation in the susceptibility to glycyrrhizic acid. In the most sensitive individuals a regular daily intake of no more than about 100 mg glycyrrhizic acid, which corresponds to 50 g liquorice sweets (assuming a content of 0.2% glycyrrhizic acid), seems to be enough to produce adverse effects. Most individuals who consume 400 mg glycyrrhizic acid daily experience adverse effects. Considering that a regular intake of 100 mg glycyrrhizic acid/day is the lowest-observed-adverse-effect level and using a safety factor of 10, a daily intake of 10 mg glycyrrhizic acid would represent a safe dose for most healthy adults. A daily intake of 1-10 mg glycyrrhizic acid/person has been estimated for several countries. However, an uneven consumption pattern suggests that a considerable number of individuals who consume large amounts of liquorice sweets are exposed to the risk of developing adverse effects.

Animals↗
PubMed1993

Diet and melanoma. An exploratory case-control study.

This population-based case-control study contrasted nutrient intakes of 41 women with cutaneous malignant melanoma to those of 297 women sampled from the same community (Brisbane, Australia). Diet was assessed by a comprehensive food frequency questionnaire. The strong inverse relation we observed between high intakes of polyunsaturated fatty acids and melanoma (P < 0.01) adds sufficient weight to prior findings for this persisting causal hypothesis to be abandoned. A relatively strong association with alcohol was observed: Women drinking 20 g or more (two or more drinks) daily had 2.5 (odds ratio) times the risk of melanoma as nondrinkers (95% confidence interval, 0.87 to 7.4). However, previous data are inconsistent. With regard to potential protective factors, our data fit with prior speculation that antioxidants (beta-carotene and vitamin E), zinc, and iron warrant further investigation. The nonsignificant (P = 0.18) 40% reduction in risk seen for those eating the most fish (> or = 15 g daily versus < 5 g) suggests the effects of marine oils and omega-3 fatty acids may deserve specific attention.

Adult↗
PubMed1993

The holding strength of cannulated screws compared with solid core screws in cortical and cancellous bone.

The comparative holding strength of cannulated screws (CS) versus solid core screws (SCS) has not been reported, although differences exist in the respective diameters of their outer thread and pilot drill holes. Our objectives were to characterize these differences and determine the holding power of CS compared with SCS in cortical and cancellous bone. The dimensions of the Synthes (Paoli, PA) 3.5-mm SCS, 3.5-mm CS, 6.5-mm SCS, and 7.0-mm CS were measured, and the cross-sectional area for thread purchase was calculated. Using adult canine femurs, small-fragment 3.5-mm SCS were inserted in cortical (midshaft) and cancellous (condyle) bone of one limb, and CS were placed in similar locations in the contralateral limb. The same technique was used for large-fragment CS and SCS. Pull-out testing was performed using an MTS machine (MTS Systems, Minneapolis, MN) with axial loads applied at 5 mm/s, and data were analyzed to determine the effects of screw type, location, and size. Differences in CS versus SCS design result in higher cross-sectional areas available for SCS thread purchase. Yet no significant differences exists between screw types (SCS vs. CS) in either cortical or cancellous bone. In cancellous bone, large-fragment screws required more force to pull out than did small screws (p = 0.000). The mean force required to pull out small-fragment screws was higher in cortical bone than in cancellous bone (p = 0.000). These data suggest that the clinical decision to use CS versus SCS should not be based on pull-out strength.

Animals↗
PubMed1993

Paraneoplastic syndromes: a challenge for neuroscience nursing.

Neurologic paraneoplastic syndromes are medical and nursing challenges. Although neurologic paraneoplastic syndromes are relatively rare in the total cancer population, they may be more commonly seen in the acute neurologic setting. O'Neill et al estimate that 60% of persons with Eaton-Lambert syndrome and 50% of persons with subacute cerebellar degeneration have an underlying cancer. The slow and subtle development of neurologic paraneoplastic disorders underscores the need for careful evaluation of persons with neurologic deficits. Once the diagnosis is made, nursing care must be based on the problems associated with paraneoplastic manifestations of the disease, as well as effects of the cancer and its treatment.

Aged↗
PubMed1993

Influence of genes within the MHC on mortality and brain cyst development in mice infected with Toxoplasma gondii: kinetics of immune regulation in BALB H-2 congenic mice.

Previous work has shown that genes within the major histocompatibility complex (MHC) of the mouse influence resistance and susceptibility to Toxoplasma gondii infection. Initial studies presented here using B10 H-2 congenic and recombinant haplotype mice inoculated via the oral route with the low virulence Beverley strain of T. gondii confirm the D region localization of MHC-linked control of brain cyst number. All B10 mice were, however, exquisitely sensitive to minor changes in virulence of the parasite inoculum resulting in high mortality during the early acute phase of infection. Further experiments examining mortality and brain cyst number in BALB MHC congenic mice inoculated via different routes indicated that the BALB background would provide a more favourable genetic environment in which to analyse kinetics of MHC controlled immune regulation following infection via the natural (oral) route. In studies comparing d and k haplotype mice a dramatic inverse relationship between splenic CD4:CD8 T cell ratios and brain cyst number was observed, particularly in the strain (BALB/K; H-2k) most susceptible to high brain cyst numbers and subsequent toxoplasmic encephalitis. Of particular interest was the observation that splenomegaly and the relative increase in the splenic CD8 T cell population preceded and accompanied the very dramatic and rapid increase in brain cyst formation. The results suggest that the too rapid development of a potent anti-parasite response in the viscera may drive the parasite to encyst in the brain.

Animals↗
PubMed1993

Subcutaneous fat necrosis of the newborn and hypercalcemia: case report and review of the literature.

Subcutaneous fat necrosis of the newborn (SCFN) alone is an uncommon condition. Its association with hypercalcemia has been reported in 19 neonates since 1926. The two occur in full-term to postterm newborns with perinatal complications associated with delivery. Erythematous to violaceous, firm, subcutaneous nodules appear approximately 1 to 4 weeks after delivery, preceding the development of signs and symptoms of hypercalcemia. Although SCFN and hypercalcemia are rare complications in neonates with perinatal problems, death due to the sequelae of hypercalcemia occurred in 3 of the 19 patients. A neonate who develops skin lesions consistent with SCFN should be followed for possible onset of hypercalcemia and treated in a timely fashion.

Fat Necrosis↗
PubMed1993

Bioactivation of 2-amino-1-methyl-6-phenylimidazo[4,5-b]-pyridine by liver microsomes from three different rat strains.

The biotransformation of 2-amino-1-methyl-6-phenylimidazo[4,5-b]-pyridine (PhIP) and the protein binding of PhIP and 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) was studied using microsomes from PCB-pretreated or untreated male rats of the strains, Wistar, Fischer and Sprague-Dawley. The microsomal monooxygenases, P450IA1 and IA2, which are important for the biotransformation of heterocyclic amines, were quantified by immunoblots. The two metabolites detected, 2-amino-1-methyl-6-(4'-hydroxyphenyl)imidazo[4,5-b]pyridine (4'OH-PhIP) and 2-hydroxyamino-1-methyl-6-phenylimidazo[4,5-b]pyridine (N2-OH-PhIP) were formed in similar amounts whereas no minor metabolites were found in our highly sensitive radiochemical assay. Irrespective of the rat strain used, pretreatment with PCB significantly induced both the activation and the detoxication in all three rat strains. Except for a significantly higher concentration of P450IA2 in microsomes from control and PCB induced Wistar rats, no major differences between the strains were found.

Animals↗
PubMed1993

Genetic control of drug-induced recovery from murine visceral leishmaniasis.

The influence of host genetic background on the response of Leishmania donovani-infected mice to chemotherapy was studied using the H-2d and H-2b haplotypes on a BALB or a B10 genetic background. Animals were treated with free or liposomal sodium stibogluconate and parasite burdens in the liver, spleen and bone marrow were assessed. In all the mouse strains and their congenic derivatives examined, the liver responded best to therapy regardless of drug formulation, whilst the spleen and the bone marrow respectively were increasingly less responsive to chemotherapy. Treatment with free drug was more effective in congenic mice carrying the H-2b haplotype than in those carrying the H-2d haplotype and in mice carrying the same H-2 haplotype, animals from a BALB background were better responders than those from a B10 genetic background. Liposomal drug was more effective than free drug treatment in all four mouse strains and produced a similar significant suppression (> 99%, P < 0.001) in liver parasite burdens to that obtained using a six times greater free drug dose. This liposomal drug dose was more effective than free drug in reducing bone marrow parasite burdens in all four mouse strains and equally (BALB/c mice) or more effective (P < 0.01, BALB/B, B10 and B10.D2 strains) in reducing spleen parasite numbers. Liposomal dependent influences apparent using free sodium stibogluconate. These results are discussed in relation to the genetic factors which are known to control the course of L. donovani infection in mice.

Animals↗
PubMed1993

Hospital board effectiveness: relationships between governing board composition and hospital financial viability.

OBJECTIVE: Two theories--agency and managerialism--are compared with respect to their usefulness in explaining the role of insiders on the hospital board: whether their participation enhances or impairs board financial decision making. DATA SOURCES/STUDY SETTING: The study used 1985 hospital financial and governing board data for a representative sample of acute care California hospitals. STUDY DESIGN: Relationships were examined cross-sectionally between the presence or absence of insiders on the board and measures of hospital financial viability while controlling for the organizational factors of system affiliation, ownership, size, region, and corporate restructuring. PRINCIPAL FINDINGS: Multiple regression analysis found significant relationships between insider (CEO, medical staff) participation and hospital viability. CONCLUSIONS: These results support the managerial theory of governance by suggesting that the CEO and medical staff provide informational advantages to the hospital governing board. However, the cross-sectional design points to the need for future longitudinal studies in order to sequence these relationships between insider participation and improved hospital viability.

Analysis of Variance↗
PubMed1992

[Cancer in Pasvik. II. Pollution from Nikel--no relationship after all?].

Previous medical investigations have indicated a connection between heavy metal pollution from the metallurgical industry in the Russian town of Nikel on the Kola peninsula and an observed increase of incidence of cancer among the Norwegian population living near the Russian border. This report contains the latest measurements of heavy metals in the local environment and discusses exposure levels in relation to possible health effects. It is concluded that exposure to heavy metals via food, water and air is considered so low as to be unlikely to cause any increase in incidence of cancer. Thus, the previously held hypothesis of a connection between heavy metal pollution from Nikel and cancer in Pasvik is not confirmed.

Adult↗