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Biomedical subjects

J Dick

Publications and source records attributed to J Dick.

At least 19 recordsLinked to original sources
PubMed1995

Blocking of NMDA receptors during a critical stage of development reduces the effects of nerve injury at birth on muscles and motoneurones.

Blocking of NMDA receptors during a critical stage of development reduces the effects of nerve injury at birth on muscles and motoneurones. Injury to the sciatic nerve at birth causes many motoneurones to soleus and extensor digitorum longus (EDL) muscles of rats to die. This is reflected in a reduction of motor units in these muscles. In the soleus only 4 (12.3%) motor units remain while 10 (24.3%) remain in the EDL, showing that soleus alpha motoneurones are more sensitive to nerve injury at birth. Treatment with MK-801, an NMDA receptor blocker, rescues a proportion of motor units in both muscles, so that in the soleus 11 (36%) and in the EDL 17 (42%) of motor units survive. This loss of motor units results in muscle weakness and a reduction in force of both muscles. Treatment with MK-801 reduces the effect of nerve injury, so that muscles of treated animals are stronger and weigh more. Cross-sectional area and muscle fibre number in EDL muscles were assessed and found to be dramatically reduced after nerve injury at birth, so that the area was 20% of control, with only 13% of fibres remaining. Moreover the majority of the remaining EDL muscle fibres which are normally fast are converted into slow type I fibres, with 68% of fibres expressing slow myosin compared with 3% in control EDL muscles. In animals treated with MK-801 only 47% of muscle fibres are lost after nerve injury at birth, hence the area of the muscle is greater (51% of control). The change of muscle phenotype induced by nerve injury is prevented and the muscle fibre composition resembles that of normal EDL muscles in that 4% of muscle fibres express slow myosin compared with 3.5% in control EDL muscles. Thus, blocking NMDA receptors with MK-801 shortly after nerve injury at birth reduces the loss of motor units and this is directly reflected in an improved performance of the affected muscles.

Animals↗
PubMed1995

Vancomycin levels in the vitreous cavity after intravenous administration.

PURPOSE: We studied the effects of inflammation, repeated antibiotic doses, and the surgical status of the eye on penetration of vancomycin hydrochloride into the rabbit vitreous cavity after intravenous administration. METHODS: We studied three anatomic states (phakic, aphakic, and aphakic, vitrectomy-treated eyes) subdividing each into inflamed and noninflamed groups. Intravenous vancomycin hydrochloride (15 mg/kg of body weight) was administered every 12 hours for 48 hours. Eyes were harvested for the assay of vitreous cavity antibiotic levels at various intervals from one to 49 hours. We determined concentrations and calculated mean values and S.E.M. RESULTS: Therapeutic levels were not established in the vitreous cavity at any time period in the two phakic groups. At 25 hours, the inflamed aphakic eyes had concentrations of 5.05 +/- 1.9 micrograms/ml and the control noninflamed aphakic eyes 4.5 +/- 1.23 micrograms/ml; slight increases were found by 49 hours. Concentrations tested in the aphakic, vitrectomy-treated eyes at two, 13, 25, and 49 hours demonstrated progressive increases both in the inflamed eyes (5.4 +/- 2.4 micrograms/ml, 9.64 +/- 4.25 micrograms/ml, 9.2 +/- 3.96 micrograms/ml, 10.34 +/- 4.49 micrograms/ml) and noninflamed eyes (3.52 +/- 2.1 micrograms/ml, 5.4 +/- 1.96 micrograms/ml, 6.8 +/- 2.53 micrograms/ml, 8.7 +/- 5.44 micrograms/ml). CONCLUSIONS: Vitreous vancomycin concentrations in aphakic and aphakic, vitrectomy-treated eyes after intravenous administration exceed the minimal inhibitory concentrations for the usual gram-positive pathogens that create endophthalmitis, suggesting a role for intravenous vancomycin in the treatment of bacterial endophthalmitis.

Animals↗
PubMed1995

Vitreous cavity penetration of ceftazidime after intravenous administration.

PURPOSE: Penetration of ceftazidime, a third generation cephalosporin, into the vitreous cavity after intravenous administration was investigated. METHODS: Because antimicrobial penetration varies with surgical status of the eye and with inflammation, studies were conducted in phakic, aphakic, and aphakic, vitrectomized eyes in both normal and inflamed conditions. Ceftazidime 50 mg/kg was administered every 8 hours and vitreous cavity concentrations were tested at intervals from 2 to 72 hours after the initial dose. RESULTS: No penetration was found into control phakic and aphakic eyes, but drug concentrations were detected in inflamed eyes at 24 hours. Vitreous concentrations of ceftazidime in aphakic, vitrectomized eyes reached levels well above the minimal inhibitory concentration (MIC) for Pseudomonas organisms within 2 hours of intravenous administration in control eyes (8.5 micrograms/ml) and inflamed eyes (35.4 micrograms/ml). Inflammation and removal of the lens and vitreous significantly enhanced ceftazidime penetration at all time periods tested. CONCLUSION: Ceftazidime penetrates into the vitreous cavity of inflamed eyes after intravenous administration and achieves concentrations above the MIC for Pseudomonas organisms. Penetration is greatest in aphakic, vitrectomized eyes.

Animals↗
PubMed1995

Percutaneous cholecystolithotomy: risks, benefits, and long-term outcome.

BACKGROUND: For symptomatic patients with gallbladder stones and a patent cystic duct who wish to retain their 'functioning' gallbladders, percutaneous cholecystolithotomy (PCCL) offers an alternative to open or laparoscopic cholecystectomy. However, there are few data on the risks and benefits of this approach or on the long-term outcome. METHODS AND RESULTS: In 21 patients with symptomatic calcified gallstones, PCCL was successful (gallstone clearance) in 17 (81%). Four to 62 (median, 35) months after clearance 9 of the 17 remained symptom-free and stone-free, whereas 4 developed biliary sludge at 7, 30, 32, and 35 months, 2 of whom subsequently developed gallstones. In four other patients gallstones recurred without evidence of preceding biliary sludge at 9, 16, 19, and 27 months, corresponding to an actuarial gallstone recurrence rate at 36 months of 53.4 +/- SEM 15.1%, and a combined stone/sludge recurrence rate of 63.4 +/- 13.5%. CONCLUSIONS: PCCL is moderately effective but, because of the frequency of complications and sludge/stone recurrence, is likely to have only a limited residual role in the era of laparoscopic cholecystectomy.

Cholecystostomy↗
PubMed1994

The design of a case register for tuberculosis. A pilot study in the south-western Cape.

The development and piloting of a tuberculosis register that aims at providing a single source of information for the surveillance of tuberculosis and the measures for its control are discussed. Old-fashioned punch cards are appropriate in both isolated rural and sophisticated urban settings. The card system proved an effective and efficient clinic-based epidemiological tool but its implementation on a broad scale depends on the rationalisation of current administrative procedures.

Forms and Records Control↗
PubMed1992

One-stage versus two-stage anterior and posterior spinal reconstruction in adults. Comparison of outcomes including nutritional status, complications rates, hospital costs, and other factors.

Twenty-four patients undergoing anterior and posterior spinal fusion were preoperatively assessed and at weekly intervals during their hospitalization for the following: serum albumin, transferrin, total lymphocyte count, skin anergy and anthropometric measurements. Eleven patients underwent staged anterior and posterior spinal reconstruction and 13 patients underwent similar procedures in a combined fashion. The groups were similar in age, sex, diagnosis, and number of levels fused. Results of these tests were kept as well as operative time, blood loss, transfusion requirements, wound healing problems, infection, length of hospital stay, patient satisfaction, and total cost. All 24 patients had normal preoperative nutritional parameters. Seven patients in the staged group and ten in the combined group became malnourished after surgery. No patient in the combined group developed infection or a wound healing problem. Wound infections developed in two of the seven patients in the staged group after their second procedure. The average number of units of blood transfused and the operating time were similar for both groups. The average length of hospital stay for the staged group was 20 days compared to 13 days for the combined group. Total hospital bills averaged 30% less in the combined group. All patients stated that they preferred to have the procedures done under the same anesthetic. The authors conclude that protein and calorie malnutrition develops to an appreciable extent in adults undergoing anterior and posterior spinal reconstructive procedures. It therefore increases the postoperative morbidity if staged surgical procedures are performed too close together as is currently done by many spine surgeons.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Grouping of some clinically relevant gram-positive rods by automated fatty acid analysis. Diagnostic implications.

One hundred and ninety-four strains of aerobically growing Gram-positive rods of the genera Corynebacterium, Actinomyces, Arcanobacterium, Erysipelothrix, Listeria, Oerskovia, Nocardia, Rhodococcus, and of unnamed Center for Disease Control (CDC) groups were checked for cellular fatty acid profiles with the microbial Identification System (Microbial ID, Newark, Del., USA). In order to obtain unified data usable for the clinical laboratory, 24 or 48 h sheep blood agar cultures were used. It was thought that grouping and perhaps identification could be aided by this approach. With the aid of numerical analysis, four groups (two consisting of two subgroups each) were established. The discriminatory ability of the scheme, however, was only 77.2%, indicating that grouping of an unknown isolate could be done with some accuracy, but that speciation would still require biochemical testing.

Bacterial Infections↗
PubMed1989

A comparison of cyclosporin versus azathioprine treatment in renal transplants in Edinburgh.

Three year graft survival rates were calculated for 66 patients on cyclosporin and prednisolone immuno-suppression and compared to survival rates for 73 patients on azathioprine and prednisolone. There was a temporary early advantage for the cyclosporin treatment group up to four months post transplant. There was no further significant difference between the two treatment groups with graft survival rate of 81.4% in cyclosporin and 76.7% in azathioprine group at three years post transplant. Fewer of the patients on cyclosporin had acute episodes of rejection. There was no significant difference in serum creatinine or urea at one year, but the haemoglobin level was higher in cyclosporin treated patients. Cyclosporin does not appear to have increased the survival rate significantly in our centre where there is already a high graft survival with azathioprine.

Azathioprine↗
PubMed1988

Biosynthesis, import and processing of precursor polypeptides of mammalian mitochondrial pyruvate dehydrogenase complex.

An immunological analysis has been conducted of early events in the biosynthesis, import and assembly of the mammalian pyruvate dehydrogenase complex (PDC). For this purpose, monospecific polyclonal antisera were produced against the intact assembly from ox heart, Mr 8.5 x 10(6), and each of its component polypeptides, E1 alpha, E1 beta, E2, E3 and protein X. Optimal detergent-based incubation mixtures were developed for obtaining clean immunoprecipitation of PDC polypeptides and their precursors from [35S]methionine-labelled extracts of PK-15 (pig kidney), NBL-1 (bovine kidney) and BRL (Buffalo Rat liver) cells. In PK-15 cells, independent higher Mr species, corresponding to precursors of the E2, E1 alpha and E1 beta subunits of PDC, could be detected by immune precipitation and fluorography after incubation of intact cells for 4 h with [35S]methionine and 1-2 mM-2,4-dinitrophenol or 10-15 microM-carbonyl cyanide p-trifluoromethoxyphenylhydrazone. Similar precursor states could be observed in uncoupler-treated BRL or NBL-1 cells. Pre-E1 alpha, pre-E1 beta and also pre-E3, have signal sequences in the Mr range 1500-3000 while pre-E2 contains a long additional segment of Mr 7000-9000. All of these forms exhibit similar kinetics of processing to the mature subunits with a transit time of 10-12 min. In NBL-1 cells, E3 is present in the immune complexes formed with anti-PDC serum whereas this is not the case in PK-15 cells. Thus, there are significant variations in the affinity of lipoamide dehydrogenase (E3) for the E2 core structure in different species. Pre-E1 alpha accumulates only poorly in PK-15 cells and is aberrantly processed on removal of uncoupler. This precursor is markedly more stable in NBL-1 and BRL cells. The lack of detection of a precursor form of component X is also discussed.

2,4-Dinitrophenol↗
PubMed1988

An unusual interpodocyte cell junction and its appearance in a transplant graft kidney.

In a case of focal and segmental glomerulonephritis unusual cell junctions were discovered between podocytes. These most closely resembled lesions described in aminonucleoside induced nephrosis in rats and were unlike anything previously seen in our experience. Shortly after renal transplantation nephrotic syndrome recurred and biopsy specimens showed recurrent focal and segmental glomerulonephritis, with the appearance of these unusual interpodocyte junctions in the graft kidney. This may be related to circulating factors in the blood of the patient.

Female↗