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Biomedical subjects

J A Campbell

Publications and source records attributed to J A Campbell.

At least 19 recordsLinked to original sources
PubMed2000

A new Eimeria sP. from the plumbeous Central American caecilian, Dermophis mexicanus (amphibia: gymnophiona) from Volcán Tajumulco, Department of San Marcos, Guatemala.

Fresh fecal samples from 5 caecilians (Dermophis mexicanus) were collected and examined for coccidia in the summer of 1998. The caecilians were collected in the Department of San Marcos, Guatemala. Two of the 5 (40%) specimens of caecilians contained an Eimeria species that is described here as new. This represents the first coccidia described from a gymnophionian host. Sporulated oocysts are spheroidal to subspheroidal, 19.5 X 17.7 (16-23 x 15-21) microm, micropyle and oocyst residuum are absent, and 3 (or more) polar granules are always present. Sporocysts are ovoidal, 11.0 X 7.2 (10-12 x 6-9); a Stieda body and sporocyst residuum are present.

Amphibians↗
PubMed1999

Crystal structures of MMP-1 and -13 reveal the structural basis for selectivity of collagenase inhibitors.

The X-ray crystal structures of the catalytic domain of human collagenase-3 (MMP-13) and collagenase-1 (MMP-1) with bound inhibitors provides a basis for understanding the selectivity profile of a novel series of matrix metalloprotease (MMP) inhibitors. Differences in the relative size and shape of the MMP S1' pockets suggest that this pocket is a critical determinant of MMP inhibitor selectivity. The collagenase-3 S1' pocket is long and open, easily accommodating large P1' groups, such as diphenylether. In contrast, the collagenase-1 S1' pocket must undergo a conformational change to accommodate comparable P1' groups. The selectivity of the diphenylether series of inhibitors for collagenase-3 is largely determined by their affinity for the preformed S1' pocket of collagenase-3, as compared to the induced fit in collagenase-1.

Amino Acid Sequence↗
PubMed1998

Purification and characterization of EDTA monooxygenase from the EDTA-degrading bacterium BNC1.

The synthetic chelating agent EDTA can mobilize radionuclides and heavy metals in the environment. Biodegradation of EDTA should reduce this mobilization. Although several bacteria have been reported to mineralize EDTA, little is known about the biochemistry of EDTA degradation. Understanding the biochemistry will facilitate the removal of EDTA from the environment. EDTA-degrading activities were detected in cell extracts of bacterium BNC1 when flavin mononucleotide (FMN), NADH, and O2 were present. The degradative enzyme system was separated into two different enzymes, EDTA monooxygenase and an FMN reductase. EDTA monooxygenase oxidized EDTA to glyoxylate and ethylenediaminetriacetate (ED3A), with the coconsumption of FMNH2 and O2. The FMN reductase provided EDTA monooxygenase with FMNH2 by reducing FMN with NADH. The FMN reductase was successfully substituted in the assay mixture by other FMN reductases. EDTA monooxygenase was purified to greater than 95% homogeneity and had a single polypeptide with a molecular weight of 45,000. The enzyme oxidized both EDTA complexed with various metal ions and uncomplexed EDTA. The optimal conditions for activity were pH 7.8 and 35 degreesC. Kms were 34.1 microM for uncomplexed EDTA and 8.5 microM for MgEDTA2-; this difference in Km indicates that the enzyme has greater affinity for MgEDTA2-. The enzyme also catalyzed the release of glyoxylate from nitrilotriacetate and diethylenetriaminepentaacetate. EDTA monooxygenase belongs to a small group of FMNH2-utilizing monooxygenases that attack carbon-nitrogen, carbon-sulfur, and carbon-carbon double bonds.

Cations↗
PubMed1997

Combining a neural network with case-based reasoning in a diagnostic system.

This paper presents a new approach for integrating case-based reasoning (CBR) with a neural network (NN) in diagnostic systems. When solving a new problem, the neural network is used to make hypotheses and to guide the CBR module in the search for a similar previous case that supports one of the hypotheses. The knowledge acquired by the network is interpreted and mapped into symbolic diagnosis descriptors, which are kept and used by the system to determine whether a final answer is credible, and to build explanations for the reasoning carried out. The NN-CBR model has been used in the development of a system for the diagnosis of congenital heart diseases (CHD). The system has been evaluated using two cardiological databases with a total of 214 CHD cases. Three other well-known databases have been used to evaluate the NN-CBR approach further. The hybrid system manages to solve problems that cannot be solved by the neural network with a good level of accuracy. Additionally, the hybrid system suggests some solutions for common CBR problems, such as indexing and retrieval, as well as for neural network problems, such as the interpretation of the knowledge stored in a neural network and the explanation of reasoning.

Artificial Intelligence↗
PubMed1997

Effect of resistance exercise and growth hormone on bone density in older men.

OBJECTIVE: The purpose of this study was to evaluate whether 16 weeks of heavy resistance exercise training combined with daily growth hormone administration (GH) increases bone mineral density in 64-75-year-old men greater than resistance exercise training without GH supplementation. DESIGN: Eighteen healthy, elderly men (67 +/- 1 year) followed a 16-week progressive resistance training programme (75-90% maximum strength, 5-10 repetitions/set, 4 sets/day, 4 days/week) after double-blind, random assignment to either a GH (12.5 or 18 micrograms/kg/day, equivalent to 25 or 36 mU/kg/day, n = 7) or placebo (n = 11) group. MEASUREMENTS: Before and at the end of 16 weeks of resistance exercise with or without GH administration, body composition, whole body and regional bone mineral density (BMD) were determined by dual-energy X-ray absorptiometry. Serum osteocalcin and IGF-I were determined by radioimmunoassay before, during and at the end of treatment. RESULTS: Increments in fat-free mass and training-specific maximum voluntary muscle strength were similar in both groups after training. Serum insulin-like growth factor-I (IGF-I) and osteocalcin levels were increased (P < 0.05) after exercise training plus GH. In comparison to initial measures, bone mineral density (g/cm2) of the proximal femur (Ward's triangle) was increased (P < 0.05) after 16 weeks of exercise training plus placebo treatment. Sixteen weeks of exercise training plus GH treatment did not increase whole body, spine or hip (femoral neck, trochanter, Ward's triangle) bone mineral density more than exercise plus placebo treatment. CONCLUSIONS: These findings suggest that in these older men with normal bone mineral density, short-term resistance exercise training increased regional bone mineral density, but the addition of daily GH administration did not enhance whole body or regional bone mineral density despite GH-induced increments in serum IGF-I and osteocalcin. This implies that GH administration during a 16-week resistance exercise training programme may increase bone turnover without increasing bone mineral accumulation.

Aged↗
PubMed1997

Interferences of o-raffinose cross-linked hemoglobin in three methods for serum creatinine.

The interferences of o-raffinose cross-linked hemoglobin (Hemolink) were examined and compared in two serum creatinine methods on the Hitachi 717 [Boehringer Mannheim (BMC) and Synermed] and in an enzymatic creatinine method on the Vitros 750 (Johnson & Johnson). Interference was considered significant when the change in creatinine concentration from the control exceeded the 95% confidence limits of each method. Significant interference was observed for the BMC/Hitachi 717 method with Hemolink > or = 5 g/L. No interference was observed for the Synermed/Hitachi 717 assay with Hemolink up to 30 g/L in normal samples and up to 50 g/L in samples with increased creatinine. No interference was observed for the Vitros 750 assay with Hemolink up to 50 g/L at both normal and increased concentrations of creatinine. Although the BMC/Hitachi 717 method was considered unacceptable, the Synermed/Hitachi 717 and the Vitros 750 methods allow accurate quantification of serum creatinine in the presence of Hemolink.

Artifacts↗
PubMed1995

Effect of growth hormone and resistance exercise on muscle growth and strength in older men.

The purpose of this study was to determine whether growth hormone (GH) administration enhances the muscle protein anabolism associated with heavy-resistance exercise training in older men. Twenty-three healthy, sedentary men (67 +/- 1 yr) with low serum insulin-like growth factor I levels followed a 16-wk progressive resistance exercise program (75-90% max strength, 4 days/wk) after random assignment to either a GH (12.5-24 micrograms.kg-1.day-1; n = 8) or placebo (n = 15) group. Fat-free mass (FFM) and total body water increased more in the GH group. Whole body protein synthesis and breakdown rates increased in the GH group after treatment. However, increments in vastus lateralis muscle protein synthesis rate, urinary creatinine excretion, and training-specific isotonic and isokinetic muscle strength were similar in both groups, while 24-h urinary 3-methylhistidine excretion was unchanged after treatment. These observations suggest that resistance exercise training improved muscle strength and anabolism in older men, but these improvements were not enhanced when exercise was combined with daily GH administration. The greater increase in FFM with GH treatment may have been due to an increase in noncontractile protein and fluid retention.

Aged↗
PubMed1995

Tuberculosis of the knee in children.

We reviewed 33 children with tuberculosis of the knee treated during the period from 1979 to 1991. All were treated with triple chemotherapy, using rifampicin, isoniazid and pyrazinamide for nine months. No patient had a synovectomy; surgery was limited to open biopsy or salvage procedures such as posterior release and arthrodesis for late stages of the disease. The radiological appearance of the knee at presentation predicted the outcome. The 30 patients with stage-1 (normal) or stage-2 (osteomyelitic) disease had excellent or good results; the three with narrowed joint spaces in stage 3 or stage 4 (arthritic) had fair or poor results. Early active mobilisation, as against long-term immobilisation, seemed to have no effect on the outcome of stage-1 or stage-2 disease.

Antitubercular Agents↗
PubMed1995

Tuberculosis of the hip in children.

We have reviewed 74 tuberculous hips in 73 children treated from 1950 to 1991. From 1979 to 1991 we treated 28 patients with rifampicin, isoniazid and pyrazinamide given for nine months (series A), using active mobilisation for the more recent cases. Before this, 46 hips had been treated with streptomycin and isoniazid with or without para-aminosalicyclic acid given for a mean of 18 months (series B), and all these patients were immobilised for a mean of 2.2 years. The radiological appearances at presentation as classified by Shanmugasundaram (1983) predicted the outcome. Most hips were of the 'normal' type (50% and 59% of series A and B respectively) followed by the dislocating type (25% and 13%) and the atrophic type (8% and 9%). There were good or excellent results in 93% of the 'normal' type. All the atrophic type had poor results. The dislocating type had a poor result if the joint space was narrow after reduction of the hip. Early mobilisation had no effect on the outcome of the 'normal' type of disease. The newer drug regimens allowed for shorter courses of treatment, but did not necessarily give a better outcome.

Adolescent↗
PubMed1994

Issues in chemical dependency treatment and aftercare for people with learning differences.

Without major adaptations, current substance abuse treatment models may not be productive for people with learning differences. The study described in this article examined ways to create accessibility to generic chemical dependency treatment for people with learning differences. A key informant survey of chemical dependency workers and developmental disabilities workers was conducted to determine the needs of chemical dependency treatment programs, staff, and people with learning differences in making treatment accessible. Training and information needs were identified, and responses were compared between the two groups of providers. Chemical dependency treatment staff need more information and training on differing learning and socialization skills, differences in reading comprehension, and personal prejudices or stereotypes. In-depth screening is also required to determine the appropriateness of integrated or specialized services or some combination of both.

Adult↗
PubMed1993

Complications in ventricular cerebrospinal fluid shunting.

The development of effective cerebrospinal fluid (CSF) shunts represents a landmark achievement in neurosurgery. This success, however, has been tempered by a high incidence of serious complications that accompany the diversion of CSF. This article examines the various complications of CSF shunting, including proximal, valve, and distal obstruction; infection; and other rare complications, and management of these complications.

Cerebrospinal Fluid Shunts↗
PubMed1992

Cytogenetic studies of mice exposed to styrene by inhalation.

The data for the in vivo genotoxicity of styrene (STY) are equivocal. To evaluate the clastogenicity and sister-chromatid exchange (SCE)-inducing potential of STY in vivo under carefully controlled conditions, B6C3F1 female mice were exposed by inhalation for 6 h/day for 14 consecutive days to either 0, 125, 250 or 500 ppm STY. One day after the final exposure, peripheral blood, spleen, and lungs were removed and cells were cultured for the analysis of micronucleus (MN) induction using the cytochalasin B-block method, chromosome breakage, and SCE induction. Peripheral blood smears were also made for scoring MN in erythrocytes. There was a significant concentration-related elevation of SCE frequency in lymphocytes from the spleen and the peripheral blood as well as in cells from the lung. However, no statistically significant concentration-related increases were found in the frequency of chromosome aberrations in the cultured splenocytes or lung cells, and no significant increases in MN frequencies were observed in binucleated splenocytes or normochromatic erythrocytes in peripheral blood smears.

Administration, Inhalation↗
PubMed1992

Unusual growth characteristics of human melanoma xenografts in the nude mouse: a model for desmoplasia, dormancy and progression.

When human melanoma cells are injected into nude mice they usually give rise to tumours that grow progressively and do not elicit a prominent host response. We have recently developed a melanoma cell line, UCT-Mel 7, that did not show these characteristics. In the first place UCT-Mel 7 showed a consistently unusual, phasic growth pattern. After a short initial period of limited growth (phase 1), the tumour ceased growing and remained static for 2-3 months (phase 2). The tumour then regressed (phase 3) to enter a second period of quiescence (phase 4) which was eventually broken by the emergence of a rapidly growing lethal tumour (phase 5). Of particular interest was the fact that the rate at which the tumours grew correlated closely with their collagen content. During the prolonged, phase 2 plateau, the tumours were intensely desmoplastic; rapidly growing phase 5 tumours, that had escaped from dormancy, contained very little collagen and virtually no reticulin. This cell line helps to fill an important need for an experimental system for the study of desmoplasia, dormancy and progression.

Animals↗
PubMed1992

Weighted needle pinprick sensory thresholds: a simple test of sensory function in diabetic peripheral neuropathy.

A simple device is described, consisting of 12 weighted 23 gauge disposable needles (0.2 to 5.2 g), for testing sensation in busy diabetic clinics. The pinprick sensory threshold (PPT) is the lightest weighted needle which consistently elicits a sharp sensation. The subjects were 48 healthy controls (hospital staff), 44 diabetic patients without neuropathic symptoms, and 35 diabetic patients with chronic painful neuropathy. In the controls, the mean PPT from the right hand and foot obtained on two test occasions a week apart did not differ significantly. In diabetic patients without symptomatic neuropathy, the mean PPT in the right hand and right foot were significantly higher than in the controls. The diabetic patients with painful neuropathy had clearly increased mean PPT in the right hand and foot compared with controls. Marstock thermal limen in diabetic patients with painful neuropathy correlated significantly with PPT determinations. PPT and thermal thresholds probably give comparable information on small fibre dysfunction in diabetic patients with symptomatic neuropathy. Compared with thermal threshold determinations however, the weighted needle apparatus is inexpensive, simple, and rapid to use.

Adolescent↗