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Biomedical subjects

G Rogers

Publications and source records attributed to G Rogers.

At least 55 records · Page 3Linked to original sources
PubMed1995

Enhanced glutamatergic neurotransmission facilitates classical conditioning in the freely moving rat.

Centrally active drugs that enhance alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor-gated currents by increasing the amplitude and duration of fast, excitatory synaptic responses in the hippocampus have recently been described. The effects of the compound 1-(1,3-benzodioxol-5-ylcarbonyl) perperidine (BDP) on associative and non-associative aspects of the classically conditioned eyeblink response in the freely moving rat were examined. Rats injected with BDP blinked significantly more to an acoustic stimulus of 85 dB than did vehicle controls, indicating that the drug enhances alpha responding to discrete auditory cues. Using a less intense stimulus of 80 dB, rats injected with BDP did not exhibit alpha responding or pseudo-conditioning, yet learned the conditioned response at a facilitated rate. These results suggest that increasing excitatory neurotransmission enhances the processing of sensory information and may contribute to subsequent contingency detection.

Acoustic Stimulation↗
PubMed1995

Classification of single-trial ERP sub-types: application of globally optimal vector quantization using simulated annealing.

Examination of the single trials which are traditionally averaged to form late-component ERPs reveals a number of different sub-types of response. This study introduces an automated and robust approach to objectively classify these ERP sub-types. Auditory oddball ERP (target tones) data were examined in 25 normal subjects. Globally optimal vector quantization using simulated annealing (the "Metropolis algorithm") was employed to determine the natural groupings of the single-trial responses that constitute the average ERP. No prior assumptions about the ERP patterns were imposed. This is the first study to employ a cluster analysis technique with globally optimal properties in ERP research. We demonstrate that, due to the presence of many different undesirable local minima, a globally optimal solution is crucial if the classification of the single-trial ERPs is to reflect their real structure. The results of this study showed that only around 40% of single trials had a morphology which resembled the averaged ERP wave form. The remaining single trials had a response morphology which was different from the average, in terms of the amplitude and latency of the components. Single-trial ERP response sub-types may provide fundamental complementary functional information to the ERP average.

Acoustic Stimulation↗
PubMed1995

Targeted expression of SV40 T antigen in the hair follicle of transgenic mice produces an aberrant hair phenotype.

Directed expression of SV40 large T antigen (TAg) in transgenic mice can induce tissue-specific tumorigenesis and useful cell lines exhibiting differentiated characteristics can be established from resultant tumor cells. In an attempt to produce an immortalised mouse hair follicle cortical cell line for the study of hair keratin gene control, SV40 TAg expression was targeted to the hair follicles of transgenic mice using a sheep hair gene promoter. Expression of SV40 TAg in the follicle cortex disrupted normal fiber ultrastructure, producing a marked phenotypic effect. Affected hairs were wavy or severely kinked (depending on the severity of the phenotype) producing an appearance ranging from a ruffled coat to a stubble covering the back of the mouse. The transgenic hairs appeared to be weakened at the base of the fibers, leading to premature hair-loss and a thinner pelage, or regions of temporary nudity. No follicle tumors or neoplasia were apparent and immortalisation of cortical cells could not be established in culture. In situ hybridisation studies in the hair follicle using histone H3 as a cell proliferation marker suggested that cell proliferation had ceased prior to commencement of K2.10-TAg expression and was not re-established in the differentiating cortical cells. Hence, TAg was unable to induce cell immortalisation at that stage of cortical cell differentiation. However, transgenic mice developed various other abnormalities including vertebral abnormalities and bladder, liver and intestinal tumors, which resulted in reduced life expectancy.

Animals↗
PubMed1995

Educating case managers for culturally competent practice.

This article provides a rationale for incorporating cultural competence into case management practice and examines the content required in educational programs for preparing case managers with appropriate and relevant knowledge, values, and skills. Cultural competence and related concepts are defined and applied in the context of case management. A number of required skills for educating case managers for culturally competent practice are presented. Becoming culturally competent is a developmental process involving self-awareness, understanding others from a cultural frame of reference, and acquiring the skills to provide culturally relevant and culturally sensitive practice.

Clinical Competence↗
PubMed1994

Centrally active modulators of glutamate receptors facilitate the induction of long-term potentiation in vivo.

An experimental drug, 1-(1,3-benzodioxol-5-ylcarbonyl)piperidine, that facilitates glutamatergic transmission in brain after systemic administration was tested for its effects on the induction of long-term potentiation in the hippocampus of rats. Intraperitoneal injections of the drug markedly increased the degree and duration of long-term potentiation; similar results were obtained with an analogue of 1-(1,3-benzodioxol-5-ylcarbonyl)piperidine that was also found to improve retention of memory in a radial maze task and in an odor-matching problem. These results define tools for enhancing long-term potentiation in vivo and confirm an important prediction from the hypothesis that long-term potentiation is a substrate of memory.

Animals↗
PubMed1994

A centrally active drug that modulates AMPA receptor gated currents.

Systemic administration of the drug 1-(1,3-benzodioxol-5-ylcarbonyl)-piperidine (1-BCP) has been reported to enhance monosynaptic responses in the hippocampus in vivo and to improve spatial and olfactory memory in rats. The drug's mechanism of action was investigated in the present study using membrane patches excised from cultured hippocampal slices. The decay time of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor mediated inward currents was greatly increased by 1-BCP in a concentration dependent and reversible fashion; peak current was also enhanced but to a lesser degree. In vitro slice experiments indicated that the drug has parallel effects on the field EPSP. It is concluded that 1-BCP is a centrally active modulator of the AMPA receptor.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed1994

Facilitation of glutamate receptors enhances memory.

A benzamide drug that crosses the blood-brain barrier and facilitates DL-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor-mediated synaptic responses was tested for its effects on memory in three behavioral tasks. The compound reversibly increased the amplitude and prolonged the duration of field excitatory postsynaptic potentials in hippocampal slices and produced comparable effects in the dentgate gyrus in situ after intraperitoneal injections. Rats injected with the drug 30 min prior to being given a suboptimal number of training trials in a two-odor discrimination task were more likely than controls to select the correct odor in a retention test carried out 96 hr later. Evidence for improved memory was also obtained in a water maze task in which rats were given only four trials to find a submerged platform in the presence of spatial cues; animals injected with the drug 30 min before the training session were significantly faster than vehicle-injected controls in returning to the platform location when tested 24 hr after training. Finally, the drug produced positive effects in a radial maze test of short-term memory. Well trained rats were allowed to retrieve rewards from four arms of an eight-arm maze and then tested for reentry errors 8 hr later. The number of such errors was substantially reduced on days in which the animals were injected with the drug before initial learning. These results indicate that a drug that facilitates glutamatergic transmission enhances the encoding of memory across tasks involving different sensory cues and performance requirements. This may reflect an action on the cellular mechanisms responsible for producing synaptic changes since facilitation of AMPA receptors promotes the induction of the long-term potentiation effect.

Animals↗
PubMed1994

Building community for health: lessons from a seven-year-old neighborhood/university partnership.

This article presents two case studies highlighting the role of community conflict in the process of community empowerment. A graduate program for community health nurses (CHNs) in a large Midwestern city formed a partnership with a diverse, integrated neighborhood for the dual purposes of enhancing the community's capacity to improve its own health and teaching CHNs community organizing as a means to improve health. Central to the partnership are a broad definition of health, trust developed through long-term involvement, a commitment to reciprocity, social justice, and Freire's model of adult learning. Two initiatives that gave rise to major conflicts between community groups are analyzed. Conflicts, external and internal to the community, proved to be both powerful catalysts and potential barriers to the use of Freirian themes in community organization. Both university and community participants report needing better skills in the early recognition and management of conflict. We conclude that conflict management theory must be integrated with empowerment education theory, particularly when empowerment education is applied in a diverse community.

Adolescent↗
PubMed1993

Theatres--the power and the gory?

It is over ten years since the Centres for Disease Control (CDC) in Atlanta Georgia became aware of the first cases of what has now been recognised as the global pandemic of AIDS. There have now been reports from over 170 countries and the World Health Organisation estimates that 13 million people have been infected by the virus. This new threat has created enormous challenges for all health care workers; in addition to being a newly recognised disease the issues raised by HIV and AIDS touch upon every taboo in our society. Traditionally these are issues which have been badly handled by many healthcare workers. Of these the most obvious is death and dying of young people (25% of people with HIV are under 24 years old), but they also include drug use and the old chestnuts of sex and sexuality. The disease has tested the strengths of both individuals and organisations. All too often the cracks have shown.

HIV Infections↗
PubMed1992

Gastric acid secretion and gastrin release in the baboon.

Significant species differences have been demonstrated in gastric physiology, a factor that limits extrapolation of animal data to man. Primate physiology is thought to be similar to that of man; however, gastric function has not been adequately documented in the primate. In the present study six baboons (body weight 25.5 +/- 1.8 kg) were trained to sit in a chair and gastric acid secretion and gastrin release was studied in conscious animals. Mean basal acid secretion was 1.3 +/- 0.1 mmol (H+)/hr. Maximum output after pentagastrin (12 micrograms/kg/hr) was 9.5 +/- 0.9 mmol (H+)/hr and 11.0 +/- 0.4 mmol (H+)/hr after histamine (40 micrograms/kg/hr). A statistically significant (by cosinor analysis) circadian rhythm was demonstrated for intragastric pH over 24 hr in fasted baboons (P less than 0.001). Mean basal serum gastrin level was 37.7 +/- 8.3 pg/ml. The integrated gastrin response after administration of a protein rich meal was 2.52 +/- 0.07 ng x min/ml and this increased to 5.17 +/- 0.18 ng x min/ml (P less than 0.05) following simultaneous administration of a meal with atropine (0.2 mg/kg) (P less than 0.05). Our results suggest that there is significant basal and stimulated acid secretion in the baboon; the amount of acid secreted is similar to that reported in man. Gastric pH demonstrated a circadian rhythm. Postprandial gastrin release was significantly enhanced by cotreatment with atropine. As the present findings are similar to those previously reported in man, the baboon may be a useful model for further studies in gastric physiology and experimental peptic ulceration.

Animals↗
PubMed1992

Gastric dilatation and necrosis in bulimia: a case report.

Gastric dilatation and perforation is a rare complication in anorexia/bulimia sufferers. We describe a 24 year old female who presented with severe abdominal pain and vomiting, in whom radiographs demonstrated gross gastric dilatation and subsequent perforation. Although gastric perforation is rare, one can anticipate a rising incidence, with the apparent increase in the incidence of bulimia.

Acute Disease↗
PubMed1992

Hair follicle differentiation: expression, structure and evolutionary conservation of the hair type II keratin intermediate filament gene family.

During hair follicle development several cell streams are programmed to differentiate from the cell population of the follicle bulb. In the hair cells, a number of keratin gene families are transcriptionally activated. We describe the characterization of the type II keratin intermediate filament (IF) gene family which is expressed early in follicle differentiation. In sheep wool, four type II IF proteins are expressed. One gene has been completely sequenced and the expression of three of the genes examined in detail. The sequenced gene encodes a 55 x 10(3) Mr protein of the type II keratin IF protein family, designated KII-9 in the new nomenclature we have adopted and described in the Introduction. The gene has a similar exon/intron structure to the epidermal type II keratin IF genes. In situ hybridization experiments show that the genes are expressed in the hair cortical cells but not in the cells of the outer root sheath, inner root sheath or medulla. During hair keratinocyte differentiation the type II IF genes are sequentially activated and coexpressed in the same cells. Expression is first detected in cells in the middle of the follicle bulb located near the dermal papilla and, subsequently, two of the genes are transcriptionally activated in the differentiating keratinocytes as they migrate upwards, in the upper part of the bulb. A fourth type II IF gene is activated later. The genes with the same expression pattern are also closely related in sequence and a number of conserved elements are present in the promoters of those genes, including a novel element which is also found in the promoter of a coexpressed type I IF gene and three other hair keratin genes.

Amino Acid Sequence↗
PubMed1989

Attitudes and physical condition of unrelated bone marrow donors immediately after donation.

Annually, over 3000 bone marrow transplants are performed worldwide involving HLA-identical sibling donors. However, only 30 percent of those patients who need a bone marrow transplant have a matched sibling donor. Programs have been developed to provide volunteer unrelated bone marrow donors for patients without sibling donors. Because bone marrow donation requires a high level of altruism, especially on the part of a donor unrelated to the patient, it is important to determine the effect of donation on the donor. Serious medical complications during the collection of marrow from related donors have been reported only rarely, but there have been no reports on the psychosocial and physical effects of the bone marrow donation process on volunteer unrelated bone marrow donors. The first 20 unrelated volunteers who donated bone marrow through the authors' volunteer bone marrow donor program were surveyed. They suffered no serious emotional or physical aftereffects. Seventeen of 20 donors reported that making the decision to donate was easy, and 16 reported making the decision to donate right away. Nine of 20 donors, however, stated that a friend or family member discouraged them from donating. All 20 donors thought that they were well prepared for the donation process. Four donors thought that the donation process required more time than they expected, but four donors thought the reverse. One person thought the process was more painful than they expected; however, 12 found the process to be less painful than expected.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗