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Biomedical subjects

R Robinson

Publications and source records attributed to R Robinson.

At least 91 records · Page 5Linked to original sources
PubMed1997

Mild abnormalities in liver histology associated with chronic hepatitis: distinction from normal liver histology.

BACKGROUND: Chronic hepatitis C virus infection associated with contaminated anti-D immunoglobulin has become an issue of recent concern. The clinical course of chronic hepatitis C infection is unpredictable and histological assessment is felt to be the most reliable means of assessing disease status. Semiquantitative scoring systems have been devised, which assess degree of necroinflammatory disease activity (grade) and extent of disease progression with fibrosis (stage) in chronic hepatitis. Often, using these systems, biopsies of anti-D associated chronic hepatitis C cases show mild changes only, with low scores. The significance of these low scores is uncertain. AIMS: To evaluate the significance of low scores in chronic hepatitis. METHODS: Liver biopsies were assessed from two groups of patients in whom liver histology would be expected to be normal: 30 cases of Gilbert's syndrome and 13 necropsy cases of young people (< 45 years) with no history or risk factors for liver disease. These biopsies were scored using the histological activity index of Knodell et al and its recent modification (separation of scores for grade and stage) by Ishak et al. RESULTS: Twenty of 30 cases of Gilbert's syndrome and 11 of the 13 necropsy cases had chronic hepatitis scores of 1 or 2, whereas only eight cases of Gilbert's and two necropsy cases had scores of 0. The remaining two Gilbert's cases had scores of 3 and 5. Similar results were found using both the histological activity index of Knodell et al and the method of Ishak et al. CONCLUSION: The finding of low but positive scores using these systems in people with normal liver histology questions the reliability and significance of finding such scores in patients with chronic hepatitis and is of particular concern in the evaluation of chronic hepatitis C infection.

Adult↗
PubMed1997

Venturi vacuum systems for hypobaric chamber operations.

Physiological studies of the effects of high altitude on man often require the use of a hypobaric chamber to simulate the reduced ambient pressures. Typical "altitude" chambers in use today require complex mechanical vacuum systems to evacuate the chamber air, either directly or via reservoir system. Use of these pumps adds to the cost of both chamber procurement and maintenance, and service of these pumps requires trained support personnel and regular upkeep. In this report we describe use of venturi vacuum pumps to perform the function of mechanical vacuum pumps for human and experimental altitude chamber operations. Advantages of the venturi pumps include their relatively low procurement cost, small size and light weight, ease of installation and plumbing, lack of moving parts, and independence from electrical power sources, fossil fuels and lubricants. Conversion of three hyperbaric chambers to combined hyper/hypobaric use is described.

Altitude↗
PubMed1997

Prenatal diagnosis of Klippel-Trénaunay-Weber syndrome as a cause for in utero heart failure and severe postnatal sequelae.

Ultrasound examination led to prenatal diagnosis of Klippel-Trénaunay-Weber syndrome complicated by early fetal congestive heart failure. The postnatal course was complicated by the Kasabach-Merritt syndrome of thrombocytopenia due to platelet consumption within the haemangioma. There was need for neonatal cardiopulmonary resuscitation and limb amputation.

Abdomen↗
PubMed1996

Chromatographic analysis of photodynamically significant porphyrin dimers and trimers.

Two porphyrin dimers, dihematoporphyrin dimer (DHD) and divinyl dimer (DVD), and two porphyrin trimers, dihematoporphyrin trimer (DHT) and divinyl trimer (DVT), have been analyzed utilizing isocratic ion-pair reversed-phase high-performance liquid chromatography. Results indicate that the vinyl porphyrins can be distinguished by three peaks appearing near 15, 38, and 42 min. The hematoporphyrin complexes are identified by the appearance of a peak located at 35 min. The DVT and DVD complexes present unique chromatographic markers at 28 and 15 min, respectively. Based on the location of these chromatographic markers, it was found that the Photofrin drug must contain the DVD and the DHT complexes, but does not contain the DVT complex. The purity of the DVT complex is compromised by the presence of DHD and DHT impurities.

Chromatography, High Pressure Liquid↗
PubMed1996

Schistosomiasis: a review of cases in Wellington 1993-4.

AIM: To review those cases of Schistosoma haematobium presenting in Wellington during 1993 and 1994. METHOD: All patients receiving praziquantel during 1993 and 1994 were traced through local pharmacy records. Their clinical records were reviewed and they were contacted by phone to ensure a complete set of information was obtained. This included timing of possible exposure to the parasite, symptoms, investigations and response to treatment. RESULTS: Nine patients were identified who had been treated with praziquantel during this period. The records of six patients were available for review, all of whom had recently travelled to Africa and had swum in water contaminated with the parasite. Four had presented to medical practitioners with irritative voiding symptoms and scant intermittent haematuria. One presented with haematospermia and one after becoming aware that a friend had contracted schistosomiasis. All were treated with a single dose of praziquantel. CONCLUSIONS: This paper has demonstrated an increased number of cases of Schistosoma haematobium being identified in Wellington. The prevalence of this condition is low, but has been seen to increase recently and relates to the increasing numbers of New Zealanders touring Africa. Patients present with relatively mild, nonspecific symptoms which require a high index of suspicion to ensure that appropriate investigations are ordered. The currently available treatment is efficacious and relatively well tolerated.

Adult↗
PubMed1996

Inactivation by phthalocyanine photosensitization of multiple forms of human immunodeficiency virus in red cell concentrates.

BACKGROUND: The use of phthalocyanines in conjunction with red light has been shown to inactivate model lipid-enveloped viruses in red cell concentrates. The ability of this treatment to inactivate multiple forms of human immunodeficiency virus (HIV) was evaluated in this study. STUDY DESIGN AND METHODS: The phthalocyanines used were aluminum phthalocyanine tetrasulfonate (AIPcS4) and the silicon phthalocyanines HOSiPcOSi(CH3)2(CH2)3 N(CH3)2 (Pc 4), and HOSiPcOSi(CH3)2 (CH2)3N+(CH3)3I-(Pc 5). HIV was studied in a cell-free form, in an actively replicating form, in latently infected cells, and in blood from HIV-positive patients. RESULTS: All three phthalocyanines inactivate > or = 10(5) infectious doses of cell-free HIV. However, only Pc 4 effectively inactivated actively replicating HIV and latently infected cells. The latter was about four times as sensitive to inactivation as was actively replicating HIV. Increasing the hematocrit of red cells during treatment decreased the rate of inactivation, especially at lower light doses. Under treatment conditions that completely inactivated the laboratory isolates of HIV, cell-associated HIV in blood from HIV-positive patients was also completely inactivated. The polymerase chain reaction signal from the gag gene of HIV was not affected on treatment of cell-free virus, but it was reduced after treatment of cell-associated HIV, particularly in some latently infected cell lines. CONCLUSION: Pc 4 and red light are effective in eliminating the infectivity of HIV in red cell concentrates. The usefulness of this approach for blood banking depends on future demonstration of the preservation of red cell circulatory survival and function in vivo.

Base Sequence↗
PubMed1996

Inactivation of Trypanosoma cruzi trypomastigote forms in blood components with a Psoralen and Ultraviolet A light.

Inactivation of the blood-borne parasite Trypanosoma cruzi by UVA and 4'-aminomethyl-4,5',8-trimethylpsoralen (AMT) was studied in the blood components fresh frozen plasma (FFP) and platelet concentrate (PC). The AMT was utilized at a concentration of 50 micrograms/mL and the inactivation procedure included the flavonoid rutin (at 0.35 mM), a quencher of type I and type photo-reactants, which we have previously found to maintain platelet integrity during this treatment regimen. Within both FFP and PC, complete inactivation of the infective form of T. cruzi, the trypomastigote, was achieved at a UVA (320-400 nm radiation) fluence of 4.2 J/cm2. We note that while the infectivity of the parasite is eliminated at 4.2 J/cm2 the trypomastigote motility continues for at least 16 h-post-treatment and is inhibited only after much higher light doses. Isolation of total DNA from the parasite cells after treatment in the presence of 3H-AMT indicated that at the lethal UVA influence about 0.5 AMT adducts per kilobase pairs occurred. These results suggest that this psoralen plus UVA methodology which shows promise in enhancing the viral safety of PC, may in addition eliminate bloodborne T. cruzi, the causative agent of Chagas disease.

Animals↗
PubMed1996

In vivo collagen turnover following experimental balloon angioplasty injury and the role of matrix metalloproteinases.

Extracellular matrix formation is the major component of the restenosis lesion that develops after balloon angioplasty. Although ex vivo studies have shown that the synthesis of collagen is stimulated early after balloon angioplasty, there is a delay in accumulation in the vessel wall. The objectives of this study were to assess collagen turnover and its possible regulation by matrix metalloproteinases (MMPs) in a double-injury iliac artery rabbit model of restenosis. Rabbits were killed at four time points (immediately and at 1, 4, and 12 weeks) after balloon angioplasty. In vivo collagen synthesis and collagen degradation were measured after a 24-hour incubation with [14C]proline. Arterial extracts were also run on gelatin zymograms to determine MMP (gelatinase) activity. Collagen turnover studies were repeated in a group of 1-week postangioplasty rabbits that were treated with daily subcutaneous injections of either a nonspecific MMP inhibitor, GM6001 (100 mg/kg per day), or placebo. Collagen synthesis and degradation showed similar temporal profiles, with significant increases in the balloon-injured iliac arteries compared with control nondilated contralateral iliac arteries immediately after angioplasty and at 1 and 4 weeks. Peak collagen synthesis and degradation occurred at 1 week and were increased (approximately four and three times control values, respectively). Gelatin zymography was consistent with the biochemical data by showing an increase of a 72-kD gelatinase (MMP-2) in the balloon-injured side immediately after the second injury, peaking at 1 week, and still detectable at 4 and 12 weeks (although at lower levels). In balloon-injured arteries, the MMP inhibitor reduced both collagen synthesis and degradation. Overall, at 1 week after balloon angioplasty, GM6001 resulted in a 33% reduction in collagen content in balloon-injured arteries compared with placebo (750 +/- 143 to 500 +/- 78 micrograms hydroxyproline per segment, P < .004), which was associated with a nonsignificant 25% reduction in intimal area. Our data suggest that degradation of newly synthesized collagen is an important mechanism regulating collagen accumulation and that MMPs have an integral role in collagen turnover after balloon angioplasty.

Angioplasty, Balloon↗
PubMed1996

A state of confusion.

Explore the source record for details and available documents.

Adaptation, Psychological↗
PubMed1996

Use of force-plate analysis of gait to compare two surgical techniques for treatment of cranial cruciate ligament rupture in dogs.

OBJECTIVE: To use ground reaction forces and related impulses as an objective measurement of limb function in the comparison of 1 extracapsular and 1 intracapsular surgical technique for repair of cranial cruciate ligament rupture in dogs. ANIMALS: 18 healthy dogs. DESIGN: All dogs underwent force-plate analysis of gait prior to transection of the left cranial cruciate ligament. The dogs were randomly allotted to 3 groups. The ligamentous instability was corrected, using a modified retinacular imbrication technique (MRIT) in 1 group and an under-and-over technique in another group. No attempt was made to correct the ligamentous instability in a control group. Clinical grading of lameness and force-plate analysis of gait were performed at 4, 8, 12, 16, and 20 weeks after surgery. PROCEDURE: Peak vertical force and vertical, braking, and propulsion impulses were recorded for each limb at each time. The degree of clinical lameness was graded at each time. RESULTS: Left hind limb peak vertical forces and vertical impulses were significantly decreased at all times after surgery in the control and under-and-over technique group, compared with values before surgery. Dogs of the MRIT group had improved by 20 weeks, with no significant differences between left hind limb peak vertical forces or vertical impulses recorded before surgery and at 20 weeks. CONCLUSION: Peak vertical forces and vertical impulses in dogs undergoing MRIT repair after experimentally created cranial cruciate ligament rupture are not significantly different when values recorded for the operated limb at 20 weeks after surgery are compared with those recorded prior to surgery.

Analysis of Variance↗
PubMed1996

Cardiopulmonary changes with moderate decompression in rats.

Sprague-Dawley rats were compressed to 616 kPa (a) for 120 min then decompressed at 38 kPa/min to assess the cardiovascular and pulmonary responses to moderate decompression stress. In one series of experiments the rats were chronically instrumented with Doppler ultrasonic probes for simultaneous measurement of blood pressure, cardiac output, heart rate, left and right ventricular wall thickening fraction, and venous bubble detection. Data were collected at baseline, throughout the compression/decompression protocol, and for 120 min post decompression. In a second series of experiments the pulmonary responses to the decompression protocol were evaluated in non-instrumented rats. Analyses included blood gases, pleural and bronchoalveolar lavage (BAL) protein and hemoglobin concentration, pulmonary edema, BAL and lung tissue phospholipids, lung compliance, and cell counts. Venous bubbles were directly observed in 90% of the rats where immediate post-decompression autopsy was performed and in 37% using implanted Doppler monitors. Cardiac output, stroke volume, and right ventricular wall thickening fractions were significantly decreased post decompression, whereas systemic vascular resistance was increased suggesting a decrease in venous return. BAL Hb and total protein levels were increased 0 and 60 min post decompression; pleural and plasma levels were unchanged. BAL white blood cells and neutrophil percentages were increased 0 and 60 min post decompression and pulmonary edema was detected. Venous bubbles produced with moderate decompression profiles give detectable cardiovascular and pulmonary responses in the rat.

Animals↗