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Biomedical subjects

P Good

Publications and source records attributed to P Good.

At least 19 recordsLinked to original sources
PubMed1995

Aland island eye disease: clinical and electrophysiological studies of a Welsh family.

Clinical and molecular genetic studies were performed on a single, large, white family, in which congenital nystagmus and moderate to high refractive error segregated as a sex linked trait with manifestation in some female carriers. In this family, affected males demonstrate myopia, but a high proportion of female carriers, and some of the possibly affected males, show hypermetropia. Clinical ophthalmic examination and electrodiagnostic studies of retinal function were fully compatible with a diagnosis of either incomplete congenital stationary night blindness or of Aland island eye disease. Previous studies have mapped both disorders to the proximal short arm of the X chromosome: our molecular studies support this localisation. Incomplete congenital stationary nightblindness and Aland Island eye disease could be considered as a single entity.

Adult↗
PubMed1994

Polyadenylation of Na(+)-K(+)-ATPase beta 1-subunit during early development of Xenopus laevis.

In fully grown Xenopus oocytes, the synthesis of beta-subunits is limiting for the formation of functional Na(+)-K(+)-adenosinetriphosphatase alpha/beta-complexes (Geering, K. FEBS Lett. 285: 189-193, 1991). In the present study, we show that during oocyte growth (from stage I to stage VI) alpha 1-, but not beta 1- or beta 3-isoform, mRNAs accumulate. In addition, beta-mRNAs are apparently sequestered in an untranslated pool in fully grown oocytes (stage VI). From fertilization to morulation, the total pools of alpha 1-, beta 1-, or beta 3-mRNAs vary little. Whereas polyadenylated [poly(A)+] alpha 1- and beta 3-isoform mRNAs did not change significantly, poly(A)+ beta 1-mRNA abundance increased three- to fourfold at morulation, accompanied by a parallel increase in beta 1-protein synthesis. After midblastula transition (i.e., at early gastrula) and during neurulation, poly(A)+ alpha 1- and beta 3-mRNAs accumulated rapidly, whereas poly(A)+ beta 1-mRNA accumulation was delayed by approximately 2 h, beginning only at early neurula. Our results indicate that 1) the abundance of poly(A)+ beta 1-mRNA is rate limiting during embryonic development for the assembly of alpha 1/beta 1-heterodimers, shown to be involved in the vectorial transport of sodium in kidney cells, and 2) the polyadenylation of beta 1-mRNA is a rate-limiting factor during morulation for the synthesis and assembly of new sodium pumps at the time of blastocoel fluid formation. The 3'-untranslated region of beta 1-mRNA (but not of alpha 1-mRNA) expresses cytoplasmic polyadenylation elements (CPEs) with the consensus sequence AXX-AUUUU(A/U)(A/U)(A/U). A role of CPE in the differential polyadenylation of alpha 1- and beta 1-mRNA is proposed.

Aging↗
PubMed1993

Genetic mapping of a cone and rod dysfunction (Aland Island eye disease) to the proximal short arm of the human X chromosome.

A five generation family with an X linked ocular disorder has been investigated. The major clinical features were reduced visual acuity, nystagmus, and myopia. Although impaired night vision was not a symptom, using psychophysical and electrophysiological testing both rod and cone function were found to be abnormal in all affected males. No abnormality was detected in carrier females. Gene location studies showed X linked transmission of a gene that maps to proximal Xp11. The findings observed in this cohort are similar to those previously reported in both congenital stationary night blindness type 2 (CSNB2) and Aland Island eye disease (AIED). This study addresses whether CSNB2 and AIED are a single entity or whether the latter is a subset of the former.

Adult↗
PubMed1992

Pigment epitheliopathy with serous detachment of the retina following intravenous iron dextran.

We report a case of pigment epitheliopathy with serious detachment of the retina in a 23-year-old man following a total dose infusion of iron dextran. Initial impairment of visual acuity resolved spontaneously, along with changes in the electro-oculogram and fundus fluorescein angiogram. Ocular features of systemic iron toxicity are reviewed and the pathophysiology discussed. Practitioners using total dose iron infusion should be aware of the possible ocular complications.

Adult↗
PubMed1992

Regulation of alpha 1-beta 3-NA(+)-K(+)-ATPase isozyme during meiotic maturation of Xenopus laevis oocytes.

During progesterone-induced maturation of Xenopus oocytes, the transport and ouabain binding capacity of Na(+)-K(+)-ATPase at the plasma membrane is completely downregulated. To elucidate the mechanism and the physiological significance of this process, we have followed the fate of oocyte alpha-beta 3-Na(+)-K(+)-ATPase complexes during meiotic maturation and early embryonic development. An immunocytochemical follow-up of the catalytic alpha-subunit, ouabain binding studies, cell surface iodination, and oocyte cell fractionation combined with immunochemical subunit detection provides evidence that following progesterone treatment Na(+)-K(+)-ATPase molecules are retrieved from the oocyte plasma membrane. The enzyme complexes are recovered in an active form in an intracellular compartment in both in vitro and in vivo matured eggs. Exogenous Xenopus alpha 1- and beta 1-complexes expressed in the oocyte from injected cRNAs are regulated by progesterone similar to endogenous Na(+)-K(+)-ATPase complexes. Finally, active Na(+)-K+ pumps internalized during oocyte maturation appear to be redistributed to plasma membrane fractions during blastula formation in Xenopus embryos. In conclusion, our data suggest that endocytosis of alpha 1- and beta 3-complexes during meiotic maturation of Xenopus oocytes is responsible for downregulation of Na(+)-K(+)-ATPase activity and results in an intracellular pool of functional enzymes, which might be reexpressed during early development in response to physiological needs.

Animals↗
PubMed1990

Mesoderm induction in Xenopus laevis distinguishes between the various TGF-beta isoforms.

Induction of mesoderm in ectodermal explants of Xenopus laevis blastula embryos had previously been shown to respond selectively to TGF-beta 2, with TGF-beta s 1 and 5 having no activity in this assay. As TGF-beta s 1, 2, and 3 are frequently coexpressed in tissues, we wished to examine the activity of TGF-beta 3 relative to that of TGF-beta s 1 and 2 in this assay as well as in other in vitro assays. We report here that when the activity of recombinant TGF-beta 3 is normalized to that of TGF-beta 1 in the assay for growth inhibition in CCL-64 cells, it is also equal to that of TGF-beta 1 in assays for stimulation of both anchorage-independent growth of rat NRK cells and chemotaxis of human monocytes. In contrast, in the assay for mesoderm induction, recombinant TGF-beta 3 is 10-fold more active than TGF-beta 2, inducing expression of muscle specific alpha-actin at concentrations as low as 1 ng/ml. These results suggest that more complex systems, in contrast to individual cell types, may respond selectively to the various TGF-beta isoforms and that there might be biological consequences of TGF-beta isoform switching in vivo.

Animals↗
PubMed1989

Methadone maintenance program for AIDS-affected opiate addicts.

To slow the spread of AIDS, it may be important for substance abuse treatment programs to give priority admission to patients who are HIV-infected and infectious. A new program is described that provides methadone maintenance treatment to opiate addicts who are "AIDS affected"--heroin addicts diagnosed with AIDS, AIDS-related complex (ARC), or other significant symptoms of HIV infection. The program aims to protect the health of patients and to protect the general public by slowing the spread of the human immunodeficiency virus (HIV). This article describes the program's history and goals, its referral and patient admission process, methods of assessment and treatment planning, medical care, counseling procedures, tolerance for misbehavior, philosophy toward eventual detoxification, and procedures that maintain confidentiality.

AIDS-Related Complex↗
PubMed1988

Proximal chronic inflammatory polyneuropathy with multifocal conduction block.

The pathological findings in proximal and distal nerve biopsy specimens are described in a patient with the clinical and electrophysiological features of chronic inflammatory polyneuropathy with multifocal conduction block. Proximal onion bulb hypertrophic changes in the brachial plexus were associated with inflammatory cell infiltrates. In contrast, the sural nerve biopsy specimen showed a mild picture of mixed axonal degeneration and demyelination-remyelination without inflammatory infiltration.

Action Potentials↗
PubMed1988

Electrophysiology and metallosis: support for an oxidative (free radical) mechanism in the human eye.

Nine cases of metal intraocular foreign body are presented. This study investigates the use of electrodiagnostic techniques in the diagnosis of metallosis and as a prognostic indicator. The electro-oculogram (EOG) and the electoretinogram (ERG) indicate that there are two mechanisms of metallosis, one of which involves cytotoxic damage by siderosomes, and the other lipid peroxidation of photoreceptor outer segments and retinal pigment epithelium. The evidence suggests that the location of the foreign body in the eye determines whether either or both of these mechanisms occur. We propose that these tests can help the ophthalmologist decide when a foreign body has to be removed and give information as to the mechanism of the pathological process.

Biomechanical Phenomena↗
PubMed1985

Cost-effective selection of fire fighter recruits.

To discriminate suitable fire fighters from recurring large groups of applicants, an objective test battery was developed which screened applicants on the basis of physical, psychomotor, and mental abilities. The physical and psychomotor selection procedures first involved fundamental tests of general aerobic endurance, upper body strength, and anaerobic endurance. Successful candidates progressed to more specific tests. Measurements were made of height, weight, hamstring flexibility, balance, strength, upper body flexibility, hand-eye coordination, and the ability to negotiate a fire fighting simulation course. Results of these tests were weighted, allocating 25% to physical tests, 20% to psychomotor tests, and 39% to the simulation course. These scores were then combined with scores of several knowledge tests weighted to be 16% of the whole. This provided a computer-generated ability profile of the top applicants which was considered at their interview before a final selection board of fire service officers. Selected candidates were then required to pass a medical examination. Pearson correlation coefficient analysis of 1984 test results demonstrated general independence of the tests (R = -0.34 to R = 0.52), with the exception of bilateral grip strength (R = 0.77). The first four trials of the selection procedure screened 3,172 applicants, 16.4% of whom were finally selected for interview. City officials estimated that based on a comparison of new and previously used selection procedures, cost savings of +92,500 were being achieved by 1984.

British Columbia↗
PubMed1984

Painful lumbosacral plexopathy with elevated erythrocyte sedimentation rate: a treatable inflammatory syndrome.

Six patients had a syndrome of painful lumbosacral plexopathy and elevated erythrocyte sedimentation rate. Sural nerve biopsy in each case showed axonal degeneration and epineurial arterioles surrounded by mononuclear inflammatory cells. Differential fascicular involvement suggested an ischemic cause in three nerves, but no patient had a necrotizing vasculitis. None of the six patients had vasculitis or cancer. Three of the six were diabetic and were initially thought to have diabetic plexopathy, but deterioration continued despite control of the diabetes. These six patients appeared to have an ischemic neuropathy with an immunological basis. Five were treated with immunosuppressant drugs, and in four the plexopathy improved or was arrested. The pathogenesis is unclear, but postmortem findings in one case suggest that the syndrome does not stem from an underlying vasculitis.

Aged↗
PubMed1983

Morphometric and biochemical studies of peripheral nerves in amyotrophic lateral sclerosis.

Phrenic nerves of 11 patients with amyotrophic lateral sclerosis studied postmortem contained only 33% of the normal number of large myelinated fibers (9 controls; p less than 0.001). In the phrenic nerves of these patients, there were 18% fewer large myelinated fibers in the distal segment than in the proximal segment (p less than 0.025). The ratio of axonal circumference to myelin lamellae in large myelinated fibers in the distal segment was 34% greater than that in control fibers (p less than 0.002). The proportion of acute axonal degeneration was the same at all levels (48.0 +/- 13.7%). Sural nerves of 21 patients with amyotrophic lateral sclerosis had more acute axonal degeneration and 30% fewer myelinated fibers (p less than 0.05) than controls; evidence of degeneration also extended to unmyelinated fibers. The amount of axonal transport of acetylcholinesterase in 9 sural nerves determined in vitro was reduced by 24% (p less than 0.05) and the apparent transport rate was reduced by 44% (p less than 0.01) compared with 4 controls. These findings show that in amyotrophic lateral sclerosis a small degree of dying-back change and of distal axonal atrophy is superimposed on the degeneration of motor neuron cell bodies, and that the disease effects spread beyond the motor neurons.

Acetylcholinesterase↗
PubMed1983

Sympathetic postganglionic unmyelinated axons in the rat peripheral nervous system.

We determined the contribution made to the unmyelinated axon population of the rat peripheral nervous system by sympathetic paravertebral ganglion cells. Sympathectomy, achieved by administration of guanethidine to neonatal rats, led to atrophy of the sympathetic paravertebral ganglion chain, a 95% decrease in peripheral nerve norepinephrine, and loss of 20 to 26% of the unmyelinated axons in a cutaneous nerve (sural), a muscular nerve (nerve to soleus), and a mixed nerve (sciatic). These data indicate that up to a quarter of the total population of peripheral nerve unmyelinated axons are sympathetic ganglia-derived.

Animals↗
PubMed1983

Unmyelinated axon subpopulations in the rat peripheral nervous system.

Using the neurotoxin capsaicin, we examined subpopulations of unmyelinated axons in mixed (sciatic), cutaneous (sural), and muscular (nerve to soleus) nerves. Administration of capsaicin to neonatal rats caused reduction of the sciatic nerve immunoreactive (IR)-substance P (by 45%) and IR-somatostatin (by 84%) contents. This correlated with a substantial reduction in unmyelinated axons in the sciatic and sural nerves (45% and 65%, respectively), although there was no significant decrease in unmyelinated axons in the nerve to soleus. In a parallel study, we have shown that sympathetic ganglia-derived unmyelinated axons account for about 20 to 25% of the total unmyelinated axon population in both the sural nerve and the nerve to soleus. Thus, in the sural nerve, the majority of unmyelinated axons are dorsal root ganglia-derived, contain either substance P or somatostatin, and are capsaicin-sensitive; whereas in the nerve to soleus, the majority of unmyelinated axons are dorsal root ganglia-derived but are insensitive to capsaicin and do not contain substance P or somatostatin. These latter unmyelinated axons presumably contain a yet to be defined neurotransmitter and may be the axons connecting with muscular ergoreceptors, a subpopulation of unmyelinated axons that are biochemically and functionally distinct from the unmyelinated axons of cutaneous nerves.

Animals↗
PubMed1981

Observations on the structure of the eumelanosome matrix in melanosomes of the chick retinal pigment epithelium.

Eumelanosomes from the developing chick pigment epithelium have been isolated, solubilized, and the residue collected. Examination of this material in the electron microscope provides evidence for new structural entities in the eumelanosome and information on the organization of the melanosome. This evidence suggests that there are (1) 190-A fibers arranged in a zigzag fashion, surrounding 240-A-diameter electron-lucent spaces and (2) an internal gridwork enclosing 40-50-A diameter spaces. These two structures are probably alternately layered and "rolled-up".

Animals↗