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Biomedical subjects

H E Brown

Publications and source records attributed to H E Brown.

At least 19 recordsLinked to original sources
PubMed2001

Genomic organization of the dysferlin gene and novel mutations in Miyoshi myopathy.

OBJECTIVE: Mutations in the skeletal muscle gene dysferlin cause two autosomal recessive forms of muscular dystrophy: Miyoshi myopathy (MM) and limb girdle muscular dystrophy type 2B (LGMD2B). The purpose of this study was to define the genomic organization of the dysferlin gene and conduct mutational screening and a survey of clinical features in 21 patients with defined molecular defects in the dysferlin gene. METHODS: Genomic organization of the gene was determined by comparing the dysferlin cDNA and genomic sequence in P1-derived artificial chromosomes (PACs) containing the gene. Mutational screening entailed conformational analysis and sequencing of genomic DNA and cDNA. Clinical records of patients with defined dysferlin gene defects were reviewed retrospectively. RESULTS: The dysferlin gene encompasses 55 exons spanning over 150 kb of genomic DNA. Mutational screening revealed nine novel mutations associated with MM. The range of onset in this patient group was narrow with a mean of 19.0 +/- 3.9 years. CONCLUSION: This study confirms that the dysferlin gene is mutated in MM and LGMD2B and extends understanding of the timing of onset of the disease. Knowledge of the genomic organization of the gene will facilitate mutation detection and investigations of the molecular biologic properties of the dysferlin gene.

Adolescent↗
PubMed2000

Androgenic-anabolic steroids blunt morphine-induced c-fos expression in the rat striatum: possible role of beta-endorphin.

Self-administration of large doses of androgenic-anabolic steroids (AAS) in a significant portion of the population suggests that these agents are drugs of abuse. However, acute administration of AAS did not induce striatal immediate-early genes (IEG) expression in male rats, indicating that AAS do not share a common mechanism of action with other drugs of abuse. Surveys have indicated that people who abuse AAS are more likely to self-administer other drugs of abuse than do people who do not take AAS. In the present study, chronic administration of AAS blunted the striatal c-fos response to morphine, indicating that AAS can alter the molecular responses to at least one drug of abuse. Chronic administration of AAS also increased the content of beta-endorphin in the midline thalamus, suggesting a possible mechanism by which AAS may modulate the response to morphine through regulation of thalamo-striatal neurons.

Anabolic Agents↗
PubMed1999

Utilizing hemodynamic delay and dispersion to detect fMRI signal change without auditory interference: the behavior interleaved gradients technique.

A major problem associated with the use of functional magnetic resonance imaging (fMRI) is the attendant gradient noise, which causes undesirable auditory system stimulation. A method is presented here that delays data acquisition to a period immediately after task completion, utilizing the physiological delay and dispersion between neuronal activity and its resulting hemodynamic lag. Subjects performed finger movements with the gradients off, followed by a rest period with the gradients on. This resulted in task-related signals comparable to those obtained with concurrent task performance and image data acquisition. This behavior interleaved gradients technique may be particularly useful for the studies involving auditory stimulation or overt verbal responses.

Acoustic Stimulation↗
PubMed1999

Structure-based mutagenesis of the human immunodeficiency virus type 1 DNA attachment site: effects on integration and cDNA synthesis.

Sequences at the ends of linear retroviral cDNA important for integration define the viral DNA attachment (att) site. Whereas determinants of human immunodeficiency virus type 1 (HIV-1) integrase important for replication in T lymphocytes have been extensively characterized, regions of the att site important for viral spread have not been thoroughly examined. Previous transposon-mediated footprinting of preintegration complexes isolated from infected cells revealed enhanced regions of bacteriophage Mu insertion near the ends of HIV-1 cDNA, in the regions of the att sites. Here, we identified the subterminal cDNA sequences cleaved during in vitro footprinting and used this structure-based information together with results of previous work to construct and characterize 24 att site mutant viruses. We found that although subterminal cDNA sequences contributed to HIV-1 replication, the identities of these bases were not critical for integration. In contrast, the phylogenetically conserved CA dinucleotides located at the ends of HIV-1 contributed significantly to virus replication and integration. Mutants containing one intact CA end displayed delays in peak virus growth compared to the wild type. In contrast, double mutant viruses lacking both CAs were replication defective. The A of the CA appeared to be the most critical determinant of integration, because two different U5 mutant viruses containing the substitution of TG for CA partially reverted by changing the G back to A. We also identified a U5 deletion mutant in which the CA played a crucial role in reverse transcription.

Base Sequence↗
PubMed1998

A two focal plane method for digital quantification of nuclear immunoreactivity in large brain areas using NIH-image software.

In principle, digital acquisition of cell-count data from serially-sectioned immunocytochemical material is a straightforward enterprise. First, a serial brain section is magnified by use of a microscope interfaced to a computer. Then, using appropriate hardware and software, a digital image is captured, and cellular profiles of interest are segmented from background objects according to mean grayscale intensity and pixel area. Ideally, the cells of interest would be uniformly distinguishable from other objects or areas of the image, with respect to grayscale intensity and size. However, due to non-uniformity in background staining of neuropil, immunocytochemical material often departs markedly from this ideal situation. As a consequence, determining grayscale intensity and cell size cutoff values which separate cells of interest from background becomes laborious and arbitrary. This problem can be diminished by increasing the magnification of the digitized image, which increases the figure-ground resolution of the image. However, high-magnification images make tissue navigation difficult and require that multiple images be captured. This paper describes a two focal plane procedure for obtaining cell counts from nuclear-stained immunocytochemistry material. This procedure allows the capturing and cell counting of relatively low-magnification images with high digital figure-ground resolution.

Animals↗
PubMed1998

A "step-to" gait decreases pressures on the forefoot.

Physical therapists use various gait training strategies to reduce stress on the lower extremities, but we could find no description or evaluation of the step-to gait using a cane. The purpose of this study was to evaluate the effect of a step-to gait pattern and a cane on peak plantar pressures on the forefoot and the heel. Ten healthy subjects were evaluated (five females, five males, mean age = 24.6 +/- 4.9 years). In addition, one subject with peripheral neuropathy was tested to determine if a patient could be trained to use the step-to walking pattern and show similar results. All subjects were instructed in four walking conditions; step-to with and without a cane and step-through with and without a cane. Walking speed during the step-through pattern (normal walking) was matched to the speed of the step-to pattern. For the 10 healthy subjects, peak plantar pressures and walking speed of each of the four conditions were compared using a 2 x 2 repeated measures analysis of variance. One factor was gait pattern and one factor was use of a cane. Peak plantar pressures decreased an average of 53% on the forefoot but increased an average of 14% on the heel when subjects walked using step-to gait compared with a step-through gait. There was no effect due to use of a cane or walking speed between the conditions. The patient with peripheral neuropathy demonstrated a similar pattern but greater magnitude of changes compared with the healthy subjects. The foot initiating the step-to pattern showed a reduction in peak plantar pressures on the forefoot, probably because the foot remained flat during stance phase and a large push-off was not required. The step-to pattern, however, results in a slower and less symmetrical gait. The use of a step-to gait may be beneficial for patient populations that need to reduce plantar pressures on the forefoot.

Adult↗
PubMed1996

Anesthesia during hormone administration abolishes the estrogen induction of preproenkephalin mRNA in ventromedial hypothalamus of female rats.

Estrogen treatment increases preproenkephalin (PPE) mRNA levels in the ventromedial nucleus of the hypothalamus (VMH). Roy et al. (Brain Res., 337 (1985) 163-166) discovered that anesthesia during estrogen priming could reduce female rat sexual receptivity. In the present study we tested whether the action of estrogen to induce PPE gene expression in the VMH could be similarly affected by anesthesia. By quantitative in situ hybridization and slot-blot analysis techniques we found a 1.8-fold increase in PPE mRNA levels in the VMH after 1 hour of estrogen treatment in ovariectomized (OVX) Sprague-Dawley female rats. Anesthetizing the rats with pentobarbital for 1 h during the exposure to estrogen blocked the estrogen induction of PPE mRNA in the VMH. By way of contrast no changes in the PPE mRNA levels were observed in the caudate putamen. A similar trend was seen using chloral hydrate. It appears that neuronal activity is required for the early phase of estrogen induction of PPE mRNA levels in the VMH. This in turn could be correlated with changes in female sociosexual behaviors.

Anesthesia, General↗
PubMed1996

L-arginine reverses the adverse pregnancy changes induced by nitric oxide synthase inhibition in the rat.

OBJECTIVE: Inhibition of nitric oxide synthase with N omega-nitro-L-arginine methyl ester (L-NAME) induces a preeclampsia-like syndrome of hypertension, proteinuria, intrauterine growth restriction, and renal glomerular capillary endothelial lesions in pregnant rats. We attempted to reverse these changes with late-pregnancy administration of L-arginine. STUDY DESIGN: Sprague Dawley rats with timed pregnancies received infusions of either saline solution (n = 12) (group SC) or L-NAME (n = 12) (group LC) (160 mg/kg per day) on gestational day 10 through term. On gestational day 16 half of the saline solution group (group SA) and half of the L-NAME group (group LA) received L-arginine (21 mg/kg per day) through delivery. Systolic blood pressures were determined via tail cuff on days 10, 16, and 21. Pup weights were assessed at delivery, serum and urine were collected and analyzed for nitrites and nitrates, and renal tissue was processed for histologic examination. Data were analyzed with the one-way analysis of variance and the Newman-Keuls test for multiple comparisons. RESULTS: In the L-NAME-treated animals L-arginine significantly lowered systolic blood pressure at late pregnancy (125 +/- 2.42 vs 153 +/- 3.0 mm Hg) (p < 0.01), increased mean pup weight (5.6 +/- 0.11 gm in group LA vs. 5.0 +/- 0.02 gm in group LC) (p < 0.001), decreased the degree of proteinuria (2+ vs trace), and decreased the proportion of injured glomeruli (7% vs 64%) (p < 0.001). CONCLUSIONS: Lesions induced by chronic inhibition of endothelium-derived nitric oxide synthesis (hypertension, intrauterine growth restriction, proteinuria, renal glomerulus injury) are reversed by treatment with L-arginine. These findings lend support to the potential for use of nitric oxide donors in the treatment and prevention of preeclampsia.

Animals↗
PubMed1996

Effect of ewe and lamb genotype on gestation length, lambing ease and neonatal behaviour of lambs.

To distinguish between ewe and lamb breed effects on prenatal growth, ease of parturition and early lamb behaviour, an embryo-transfer study was carried out using a hill breed (Scottish Blackface; liveweight: 54.25 +/- 1.03 kg, mean +/- s.e.m.) and a lowland breed (Suffolk; 80.33 +/- 1.52 kg) to obtain the four possible combinations of ewe and lamb. Data were collected from 38 Blackface ewes (18 with Blackface lambs and 20 with Suffolk lambs) and 41 Suffolk ewes (20 with Blackface lambs and 21 with Suffolk lambs); all ewes were given single embryos. Suffolk lambs had a significantly longer gestation than Blackface lambs (1.5 days, P < 0.01), regardless of ewe breed. Suffolk lambs also had a longer labour (20 min, P < 0.05) and were significantly more likely to require birth assistance (17/21, 81% of all assisted deliveries; P < 0.001), as were male lambs (19/21, 90%; P < 0.01). These variables were independent of ewe breed. Blackface lambs were significantly more active than Suffolk lambs in the first 2 h after birth; ewe breed had little effect on lamb behaviour. Blackface lambs stood twice as quickly as Suffolk lambs after birth (13 min v. 24 min; P < 0.001), and were significantly more likely to suckle within the first 2 h after birth (92% v. 66%; P < 0.05). The behavioural retardation of Suffolk lambs may be a consequence of their birth difficulty which increases their likelihood of suffering birth trauma and hypoxia at parturition. Together, these factors may increase the probability of neonatal death in these lambs.

Animals↗
PubMed1995

Cellular uptake of intracerebrally administered oligodeoxynucleotides in mouse brain.

Intracerebral diffusion, cellular uptake and intracellular localization of oligodeoxynucleotides (ODN) after their microinjection in mouse brains were examined. Using either tetramethylrhodamine-5-(and -6)-isothiocyanate (TRITC)- or gamma-33P ATP-labeled ODNs, it was found that both phosphodiester ODNs (D-ODN) and phosphorothioate ODNs (S-ODN) quickly diffused (up to about 500 microns) and were taken up by many cells around the injection site as early as 15 min after administration. Fluorescence labeling intensity and silver grain accumulation of D-ODNs were greatly reduced by 4 h after injection, whereas those of S-ODNs were stable beyond at least 8 h after injection. Most of labeled ODNs were found in neuronal cells as identified by immunocytochemistry for neurofilament, NF 200, and to a much lesser extent in astrocytic cells as identified by immunocytochemistry for glial fibrillary acidic protein.

Animals↗
PubMed1995

Alterations in immediate-early gene proteins in the rat forebrain induced by acute morphine injection.

Injection of morphine (10 mg/kg) induced a complex immediate-early gene response in the rat forebrain, as detected with immunocytochemistry. The c-Fos protein was induced consistently in the dorsomedial caudate-putamen, the nucleus accumbens, and in midline and intralaminar nuclei of the thalamus. In some rats induction was also seen in the parietal and insular cortex and in lateral regions of the caudate-putamen. Induction was detectable, although weak, at 30 min, was maximal at 2 h, and was undetectable 3 h after injection. JunB was induced in the same regions of the caudate-putamen as found for c-Fos, but was not induced in the nucleus accumbens or thalamus. In the caudate-putamen, JunB induction was still present 3 h after injection. A considerably smaller induction of c-Jun was noted in the dorsomedial caudate-putamen and in deep neocortex. Expression of JunD was inhibited in intralaminar and midline thalamic nuclei. Increases in numbers of cells immunoreactive for a Jun-related antigen (Jra) were found in the caudate-putamen and nucleus accumbens. These results indicate a complex immediate-early gene response to acute morphine, suggesting that morphine activates or inhibits specific neurons and circuits in the forebrain.

Animals↗
PubMed1994

Activation of protein kinase C in the hypothalamic ventromedial nucleus or the midbrain central gray facilitates lordosis.

Many neurotransmitters and neuropeptides can act through the hypothalamic ventromedial nucleus (VMN) or midbrain central gray (MCG) to facilitate lordosis. Since these lordosis-facilitating agents can also stimulate the phosphoinositide (PI) second-messenger pathway, it was hypothesized that direct activation of this pathway can also potentiate the behavior. To evaluate this possibility, a phorbol ester, TPA (12-O-tetradecanoyl phorbol 13-acetate), was used to activate a key enzyme, protein kinase C (PKC), of the PI pathway in ovariectomized (OVX) rats either primed or not primed with estrogen. These female rats were paired with males for mating tests before and after an intracerebral infusion of TPA, and both the lordosis quotient (LQ) and the lordosis strength (LS) were measured. Bilateral infusion of TPA (5 micrograms/0.5 microliter or 0.2 microgram/0.2 microliter, but not 0.1 microgram/0.2 microliter/side) into the VMN or MCG of estrogen-primed subjects facilitated both LQ and LS in 30 min, peaked at 60-90 min, and the facilitation lasted for more than 180 min. This facilitatory effect of TPA was: (1) not observed in OVX rats not primed with estrogen; (2) not observed if the infused TPA did not reach both sides of the VMN or MCG; (3) not mimicked by 4 alpha-phorbol 12,13-didecanoate, which does not activate PKC; (4) blocked by PKC inhibitors (H7 10 mM or staurosporine 1 microM, 0.2 microliter/side), which by themselves did not facilitate lordosis; and (5) was not affected by pretreatment of the progestin antagonist RU486.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaloids↗
PubMed1991

Chlordecone (Kepone) on the night of proestrus inhibits female sexual behavior in CDF-344 rats.

The effect of the estrogen-like chlorinated pesticide chlordecone (Kepone) on sexual behavior was examined in proestrous rats following treatment with 25, 50, or 75 mg/kg chlordecone. In most animals, sexual behavior, both receptivity and proceptivity, was reduced within 60 min following the higher dosage of chlordecone. Reduced sexual receptivity occurred more slowly with 50 mg/kg chlordecone (usually within 180 min) and no reduction was seen following 25 mg/kg chlordecone. The reduced sexual behavior after chlordecone treatment preceded the onset of marked chlordecone-induced tremor. A group of rats treated with 75 mg/kg chlordecone was euthanized at the time that behavioral inhibition began to develop. The content of serotonin, norepinephrine, and their principal metabolites was determined by high-performance liquid chromatography of extracts of brain tissue of these animals. In hypothalamus, increases in serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) content, and a decrease in the level of norepinephrine (NE), were detected in chlordecone-treated rats relative to matched controls which received vehicle. The content of 5-HT was also increased in preoptic area of chlordecone-treated females. The content of the catecholamine metabolite, 3,4-dihydroxy-phenylacetic acid, was unaffected by chlordecone in either part of brain. These are the first observations of the parallel effects of chlordecone on receptive and proceptive behaviors, and on neurochemistry, in female rats; the results demonstrate short-latency effects of the pesticide treatment on the CNS events that mediate female reproductive behavior. Results of previous studies had led to the suggestion that chlordecone's inhibition of sexual behaviors resulted from its interaction with the intracellular estrogen receptor. However, the rapidity of the inhibition during the period of ongoing sexual behavior makes it unlikely that the inhibition is mediated by the pesticide's action at the intracellular estrogen receptor. Because of the importance of sexual behaviors to reproductive fitness, the current results indicate that nonsteroidal, behavioral mechanisms could contribute to chlordecone's neuroreproductive toxicity.

Analysis of Variance↗
PubMed1984

The effects of a partially purified fraction of an ant venom in rheumatoid arthritis.

A partially purified extract of an ant venom from the South American tree ant Pseudomyrmex sp. was tested in a double-blind, controlled study of patients with rheumatoid arthritis. Venom treated patients demonstrated an improvement in global efficacy and a decrease in the number of tender/painful joints and swollen joints. Swollen joint index improved in 60% of venom treated patients. Other parameters did not demonstrate significant change. Reduction of joint swelling was followed by symptomatic improvement that was sometimes delayed by weeks. Reactions were limited to erythema at the injection site (all patients), local pruritus (two-thirds of the patients), and fever with malaise (one-third of the patients). Further study of this venom in rheumatoid arthritis appears warranted in view of its apparent favorable efficacy-to-toxicity ratio.

Adult↗