PubMed Health⌕ Search

Biomedical subjects

B Morris

Publications and source records attributed to B Morris.

At least 37 records · Page 2Linked to original sources
PubMed1994

Stable strontium absorption as a measure of intestinal calcium absorption: comparison with the double-radiotracer calcium absorption test.

1. Stable strontium (Sr) has been proposed as an alternative to calcium (Ca) isotopes for the measurement of intestinal Ca absorption. The aim of this study was to compare the time course and fractional absorption of Ca and Sr, when both are measured using dual-tracer techniques. 2. 45Ca and Sr absorption tests were carried out on consecutive days in patients with osteoporosis (n = 10) or chronic renal failure (n = 7). Both tests were repeated in four patients with chronic renal failure after treatment with calcitriol (1 microgram daily for 10 days). 3. The time course of Ca absorption was determined using the 85Sr (intravenous)/45Ca (oral) dual-tracer technique, and the time course of Sr absorption using 85Sr (intravenous)/stable Sr (oral). Oral tracers were administered on consecutive days with a test meal containing 5.3 mmol of Ca and 2.5 mmol of either stable Sr or Ca carrier. The fractional absorption of 45Ca and Sr at 6h (FA360) and the absorption rate as a function of time were calculated by deconvolution. 4. The mean FA360 for Sr (20.2%) was lower than the mean FA360 for 45Ca (37.8%, P < 0.001, paired t-test), but the time course of Sr absorption was similar to that of Ca. There was a significant correlation between the FA360 for 45Ca and Sr, although the relationship was improved by including a quadratic term (R2 = 0.89, P < 0.001, significance of quadratic term, P < 0.05). After 1,25-dihydroxyvitamin D treatment, the FA360 of stable Sr increased 4.29-fold, whereas the FA360 of 45Ca increased only 2.4-fold.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Assessment of adaptive transportation technology: a survey of users and equipment vendors.

In order to define the state of adaptive transportation equipment, wheelchair users with spinal cord injury (SCI) and equipment vendors were surveyed about equipment, funding, maintenance, and repair. SCI registries from two states, Virginia and Arkansas, were used to create the sample pool of users and 225 responses were received. A list of equipment vendors and vehicle modifiers was compiled from several national resources, and 123 responses were received from 36 states. User respondents were generally satisfied with their adaptive equipment, which typically required only minor inexpensive (< $100) repairs, if any. Personal or family money was used by over 90% of the respondents for equipment funding. Vendors reported that a substantial amount of custom modification or fabrication of equipment is required to meet the needs of their clients. Lifts, external controls, and six-way power seats were cited by vendors as the equipment requiring the most frequent repair. The survey results provide an examination of the opinions and experiences of users and vendors of adaptive transportation equipment, which should prove useful to those involved in evaluating equipment, equipment availability, and the need for industry-wide standards.

Automobiles↗
PubMed1994

Assessment of computed tomographic pelvimetry within a selective breech presentation management protocol.

A vital component of selective protocols in term breech presentation management is exclusion of the gravida with borderline pelvic dimensions. Computed tomographic (CT) pelvimetry was employed to evaluate potential candidates for a trial of labor with a breech fetus at term. Thirty-seven of 39 women who underwent labor after this selection had a successful assisted vaginal breech delivery. Adequate pelvic dimensions by CT pelvimetry reliably predicted a safe vaginal delivery in patients managed within a standard breech protocol.

Breech Presentation↗
PubMed1994

Tissue repair processes in healing chronic pressure ulcers treated with recombinant platelet-derived growth factor BB.

Cellular and molecular mechanisms responsible for the observed vulnerary effects of recombinant human platelet-derived growth factor BB (rP-DGF-BB) in man have not been elucidated. In a double-blinded trial, patients having chronic pressure ulcers were treated topically with either rPDGF-BB or placebo for 28 days. To explore how rPDGF-BB may induce chronic wounds to heal, biopsies were taken from the ulcers of a cohort of 20 patients from the trial and evaluated in a blinded fashion by light microscopy for 1), fibroblast content, 2) neovessel formation, and 3), collagen deposition. Electron microscopy also was used to assess fibroblast activation and collagen deposition. Before initiation of therapy most wounds had few fibroblasts and most of those present were not activated. When mean scores for the total active treatment phase (days 8, 15, and 29) for rPDGF-BB-treated ulcers were compared with the scores for placebo-treated ulcers, fibroblast content was significantly higher for the rPDGF-BB-treated ulcers (P = 0.03, Kruskal-Wallis test). More significant differences in fibroblast and neovessel content were observed when six nonhealing wounds were eliminated from the analysis (three placebo, three treatment). Thus, in all healing wounds, rPDGF-BB therapy significantly increased fibroblast (P = 0.0007) and neovessel (P = 0.02) content. These results were correlated with increased collagen fibrillogenesis by fibroblasts from healing rPDGF-BB-treated wounds, as assessed by intracellular procollagen type I immunostaining, and by electron microscopy, and were concordant with clinical measurements (eg, area of ulcer opening and ulcer volume) which showed greater healing in rPDGF-BB-treated wounds. These results suggest induction of fibroblast proliferation and differentiation is one mechanism by which rPDGF-BB can accelerate wound healing and that rPDGF-BB can augment healing responses within a majority of, but not all, nonhealing chronic pressure ulcers in man.

Antibodies↗
PubMed1993

Devising a multidisciplinary audit tool.

Discusses the audit processes in health care from the existing perspectives and argues the need to extend the current unidimensional approaches which include medical, clinical and managerial quality. Argues that one way of expanding these approaches is to develop an audit instrument based on the views of service users. The implementation of audit has been a process with regional variations, which have created centres of excellence and centres where there is very little happening. Considers elements that are involved in devising an audit tool which is based on customers' perceptions of service quality, and reports on an empirical study which is still in progress and which aims to develop a tool which is effective, efficient and based on patients' views.

Aged↗
PubMed1992

Regulation of the activities of African cassava mosaic virus promoters by the AC1, AC2, and AC3 gene products.

DNA fragments comprising each of the promoter regions from the geminivirus African cassava mosaic virus (ACMV) were cloned into the pUC18-based vector, pG1, producing transcriptional fusions with the beta-glucuronidase gene (GUS) and nopaline synthase terminator sequence. The relative activity of each promoter construct was analyzed by a GUS expression assay of extracts from Nicotiana clevelandii protoplasts coelectroporated with the GUS reporter constructs and constructs in which individual ACMV open reading frames (ORFs) were placed under control of a cauliflower mosaic virus 35 S promoter. Results suggest repression of the AC1 gene by its gene product, which is required for ACMV DNA synthesis. The promoter activity observed for the single promoter for the DNA A genes encoding functions of spread and the regulation of replication (AC2 and AC3 ORFs) was unaffected by coelectroporation with any of the ACMV ORF constructs. Promoters for the AV1 (coat protein) gene and the two DNA B genes (BV1 and BC1) were activated by electroporation of the AC2 ORF construct. To a lesser extent promoters for the AV1 and BV1 genes were activated with the AC3 ORF construct. The same pattern of promoter repression and activation was observed when transgenic N. benthamiana plants expressing the GUS reporter constructions were inoculated with ACMV DNA A.

DNA-Directed DNA Polymerase↗
PubMed1992

Cryptococcal peritonitis in a CAPD patient.

A 50-year-old diabetic woman with end-stage renal disease, who had been on continuous ambulatory peritoneal dialysis for 8 months, developed peritonitis caused by Cryptococcus neoformans var. neoformans. The patient was completely asymptomatic and infection was confirmed by detection of budding yeast cells in Gram-stained smears of turbid peritoneal fluid. The infection was cleared after intravenous fluconazole with delayed removal of the catheter. Fluconazole may be a suitable alternative drug in treating cryptococcal peritonitis.

Cryptococcosis↗
PubMed1992

Patterns of electrical activity and neural responses in canine proximal duodenum.

The patterns of electrical activity and neural inputs to the proximal duodenum between the pyloric sphincter and the sphincter of Oddi were studied in muscles of the dog. Smooth muscle cells in the most proximal region were electrically quiescent, but slow waves were recorded in all regions distal to the first few millimeters. Electrical activity was recorded from circular muscle cells near the myenteric and submucosal surfaces of the circular layer, and slow wave activity was similar in both regions. The nature of neural inputs was also characterized. With electrical field stimulation, responses in cells near the submucosal surface were predominantly excitatory junction potentials (EJPs); near the myenteric border responses were either inhibitory junction potentials (IJPs) or biphasic responses (i.e., small EJPs followed by IJPs). EJPs were blocked by atropine. IJPs were nonadrenergic and noncholinergic (NANC), and several experiments suggested that nitric oxide (NO), or a NO-releasing compound, serves as the inhibitory neurotransmitter in this region. Exogenous NO caused hyperpolarization of membrane potential. IJPs and the hyperpolarization response to NO were sensitive to apamin. These data describe the myogenic mechanisms and neurogenic apparatus that appear to regulate motility in the most proximal region of the duodenum.

Animals↗
PubMed1991

Therapeutic ratings and end-of-phase II conferences: initiatives to accelerate the availability of important new drugs.

To facilitate the availability of important new therapeutic agents, the Food and Drug Administration (FDA) in the mid-1970s began assigning therapeutic ratings to investigational new drugs and holding end-of-phase II conferences with drug sponsors. To determine whether these initiatives are associated with faster approvals, we examined new drug application (NDA) review times of new chemical entities (NCEs) approved during the 12-year period 1978 through 1989. Mean NDA review time for 1A drugs (22.5 months) was 22% shorter than that for 1B drugs (28.7 months), which in turn was 25% shorter than that for 1C drugs (38.4 months). For drugs approved during the recent 4-year period 1986 through 1989, however, the gap between 1A and 1C review times has narrowed considerably from 19 to 9 months. When drugs were grouped by FDA reviewing division, 1A drugs had the shortest mean review time in each division except the Cardio-Renal Division; in that division, 1B drugs had the shortest mean review time. Mean NDA review time for drugs that had end-of-phase II conferences (28.6 months) was 15% shorter than that for drugs without such conferences (33.7 months). These results suggest that NCEs that receive 1A or 1B ratings and are the subject of end-of-phase II conferences benefit by having shorter review times.

Drug Evaluation↗
PubMed1991

Analysis of the potential promoter sequences of African cassava mosaic virus by transient expression of the beta-glucuronidase gene.

DNA fragments from promoter regions of the geminivirus, African cassava mosaic virus, were cloned into pG1, a vector based on pUC18, producing transcriptional fusions with the beta-glucuronidase (GUS) gene and nopaline synthase termination sequence. The activity of each promoter construct was assessed by analysing the transient expression of GUS in Nicotiana clevelandii protoplasts. The results demonstrated that constructs containing the common region of DNA A showed much stronger promoter activity in the complementary sense than in the viral sense. These results were supported by the analysis of promoter activity in transgenic N. benthamiana plants. In comparison, in protoplasts a region upstream of the AC2 open reading frame was shown to have moderate promoter activity. Unlike DNA A, the complementary sense DNA B promoter constructs had weak activity; the viral sense DNA B promoter constructs appeared to be regulated by host factors. The implications of these results for the regulation of early and late genes are discussed.

Base Sequence↗
PubMed1991

Mutagenesis of the AC3 open reading frame of African cassava mosaic virus DNA A reduces DNA B replication and ameliorates disease symptoms.

Small insertions were made independently at each of four unique restriction sites on African cassava mosaic virus (ACMV) DNA A to disrupt the three overlapping complementary-sense open reading frames (ORFs) herein designated AC1, AC2 and AC3. The DNA A mutants were assayed for their infectivity by agroinoculation of monomeric constructs to Nicotiana benthamiana plants containing chromosomal insertions of ACMV DNA B. Disruption of the AC3 ORF alone resulted in a delay and amelioration of disease symptoms which correlated with reduced replication of DNA B. Normal replication of DNA A still carrying the AC3 ORF mutation was found in extracts from these plants. No ACMV DNA or symptoms were observed in corresponding inoculations with either the simultaneous disruption of the overlapping AC2 and AC3 ORFs or disruption of the AC1 ORF. Complementation by the inoculation of different mutant pairs produced a delay in disease symptoms followed by repair of mutated sites. A DNA A construct with the virus-sense AV1 (coat protein) ORF deleted was infectious producing typical ACMV disease symptoms. A similar construct with a larger deletion encompassing the complementary-sense AC3 ORF produced symptomless infections. The DNA recovered from plants revealed DNA A of normal size where the position of the deleted ORF was replaced with cloning vector DNA. Significantly reduced DNA B replication was observed for the AC3 deletion construct.

Blotting, Southern↗
PubMed1990

Differential peripheral expansion and in vivo antigen reactivity of alpha/beta and gamma/delta T cells emigrating from the early fetal lamb thymus.

The concentrations of different lymphocyte subsets in the blood of lambs which had been thymectomized (Tx) in utero between days 67-75 of fetal gestation were measured at birth and at various intervals during the first year of life. Compared to thymus-intact (Ti) controls, Tx lambs were severely depleted of both alpha/beta and gamma/delta T cells at birth (less than 10% of control levels). The majority of the residual alpha/beta T cells present in Tx lambs at birth were CD4+CD8-. As the Tx lambs aged, the concentration of alpha/beta T cells in blood increased steadily to reach levels around 50% of control values. In contrast, the circulating gamma/delta T cells did not expand in Tx animals and remained barely detectable throughout the observation period, although these cells accounted for 30%-60% of the T cells in the blood of Ti lambs. The expansion of alpha/beta but not gamma/delta T cells was also reflected in changes in the cellular composition of solid lymphoid organs in Tx lambs. B cell numbers were similar in both groups at birth but Tx lambs were persistently B lymphopenic from 3 weeks of age onwards. The alpha/beta T cells that had expanded in Tx lambs responded to stimulation with bacterial antigens in a way that was qualitatively similar to the response in Ti lambs. By contrast, the few gamma/delta T cells in Tx lambs responded abnormally. Our results show that although sheep alpha/beta and gamma/delta T cells are equally thymus dependent during ontogeny, the early fetal thymic emigrants which establish the two T cell lineages in the periphery have strikingly different antigen reactivities and capacities for self-renewal and expansion.

Aging↗
PubMed1990

Factors regulating the activity of striatal neurons: new perspectives from in situ hybridization histochemistry.

1. The basal ganglia contain a variety of putative peptide neurotransmitters. In situ hybridization allows changes in the levels of the mRNAs encoding these neuropeptides to be assessed at the cellular level of resolution. 2. Alterations in the activity of pathways within the basal ganglia of the rat produce distinct effects on the different neuropeptide mRNAs. 3. The evidence, where available, suggests that mRNA levels provide an index of peptide turnover. 4. This approach has consequently revealed much new information on the regulation of neuronal activity in the basal ganglia.

Animals↗