Biomedical subjects

R M Harris

Publications and source records attributed to R M Harris.

At least 37 records · Page 2Linked to original sources

PubMed1999

Incomplete spinal cord injury: neuronal mechanisms of motor recovery and hyperreflexia.

OBJECTIVE: To understand neuronal mechanisms of motor recovery and hyperreflexia after incomplete spinal cord injury (SCI), and their role in rehabilitation. DESIGN: Reviewed and compared clinical, neurophysiologic, and neuropathologic data from human SCI patients with behavioral, neurophysiologic, and neuroanatomic data from animals to postulate underlying neuronal mechanisms. OUTCOME: A postulation that two neuronal mechanisms-receptor up-regulation and synapse growth-act sequentially, to explain the gradual appearance of motor recovery after incomplete SCI. These same mechanisms may also act in spinal reflex pathways to mediate hyperreflexia caudal to SCI. RESULTS: After incomplete SCI, walking ability and hyperreflexia often develop. Initially, cord neurons are hyperpolarized and less excitable because of loss of normal descending facilitation; this is spinal shock. Then, gradually, voluntary movement recovers and hyperreflexia develops. Early (hours to days), these changes develop simultaneously, suggesting a common postsynaptic mechanism-likely, an increase in postsynaptic receptor excitability, possibly receptor up-regulation. Late (weeks to months), recovery and reflex changes occur at a slow rate, are no longer simultaneous, and are long-lasting, which suggests a presynaptic mechanism, such as local synapse growth in spared descending pathways and in reflex pathways. This presumed synapse growth is seemingly enhanced by active use of the growing pathway. Also, developing hyperreflexia appears to limit motor recovery. CONCLUSIONS: These observations suggest that rehabilitation for incomplete SCI should (1) increase activity in spared descending motor pathways, (2) initially use reflex facilitation or central nervous system stimulants to assist spared descending inputs in depolarizing cord neurons, and (3) later minimize reflex input, when spared descending inputs can depolarize cord neurons without reflex facilitation. Better understanding of neuronal mechanisms that underlie motor recovery after incomplete SCI promises better outcomes from rehabilitation.

Animals↗

PubMed1998

An intervention for changing high-risk HIV behaviors of African American drug-dependent women.

The purpose of this study was to test the effectiveness of an AIDS education intervention for methadone-dependent, African American women. The women were randomly assigned to experimental (n=107) or control (n=97) group. The experimental group participated in a peer counseling and leadership training program conducted by two experienced nurse counselors over an 8-week period, followed by 8 weeks of reinforcement. The program was designed to reduce AIDS high-risk sexual behavior, increase self-esteem, decrease depressive affect, and increase the women's community-based AIDS prevention communication activities. A total of 130 women completed all phases of the study, including longitudinal Posttests at 2, 4, and 7 months after enrollment. Compared to the control group, there were statistically significant differences in three of the outcomes for the experimental group: The experimental group reported an increased number of safer sexual behaviors (p=.029), showed decreases in depression (p=.001), and reported engaging in more AIDS-related, community-based communication activities regarding prevention (p=.005).

Adult↗

PubMed1998

Sulfur metabolism in ulcerative colitis: investigation of detoxification enzymes in peripheral blood.

Two enzymes of detoxification were studied in blood samples from 27 patients with ulcerative colitis (UC) and 18 controls to determine whether there is an abnormality in sulfur metabolism in UC. Thiol methyltransferase (TMT) activity was measured in erythrocyte membranes as the extent of conversion of 2-mercaptoethanol to S-methyl-2-mercaptoethanol with [3H]methyl-S-adenosyl methionine as methyl donor. Phenol sulfotransferase (PST) activity was measured in platelet homogenates as the extent of sulfation of p-nitrophenol with 3-phosphoadenosine 5-phospho[35S]sulfate (PAPS) as sulfate donor. TMT activity was significantly higher in UC patients (27.0 vs 17.1 nmol/mg protein/hr; P < 0.005). No difference in PST activity was found. We conclude that TMT may be up-regulated in UC to detoxify excess hydrogen sulfide exposed to the peripheral blood compartment. This may arise from either increased luminal sulfide production or reduced colonic detoxification.

Adult↗

PubMed1998

The roles of library liaisons in a problem-based learning (PBL) medical school curriculum: a case study from University of New Mexico.

The relationships between problem-based learning (PBL) curricula and libraries have generated a substantial number of journal articles, but few have addressed the importance of the interaction between health science libraries and PBL curricula. This article attempts to contribute to this dimension through a description of the roles of library liaisons. First we describe the evolution of the liaison roles beginning 2 years prior to the implementation of a PBL curriculum. We then describe the core responsibilities of liaisons at the University of New Mexico (UNM) with mention of other innovative roles developed by some liaisons.

Curriculum↗

PubMed1998

Inhibition of phenolsulphotransferase by salicylic acid: a possible mechanism by which aspirin may reduce carcinogenesis.

BACKGROUND: Recent epidemiological evidence has shown that chronic use of aspirin decreases susceptibility to bowel cancer. Animal studies have shown that sulphotransferase inhibitors coadministered with sulphation activated carcinogens dramatically reduce the incidence of cancer. AIMS: To investigate the effect of the main aspirin breakdown product, salicylic acid, on the P and M isoforms of phenolsulphotransferase from human platelets and colonic mucosa. METHODS: Platelets were obtained from healthy blood donors and isolated within 24 hours after donation. Samples of colonic mucosa were obtained at resection for non-malignant disease. Phenolsulphotransferase activity was measured in cellular homogenates using a standard radiolabelling assay. RESULTS: Salicylic acid consistently and selectively inhibited the P form of phenolsulphotransferase at subtherapeutic concentrations in both tissue samples. A 50% inhibition of sulphation by the P phenolsulphotransferase occurred at salicylic acid concentrations of about 40 and 130 microM in platelets and bowel mucosa respectively. M phenolsulphotransferase was virtually unaffected by salicylic acid up to a concentration of 1.5 mM (the therapeutic plasma concentration for salicylates when treating rheumatoid arthritis is about 1-2 mM). CONCLUSION: The action of salicylic acid on P phenolsulphotransferase, by preventing the excessive activation of carcinogens, is a possible additional pathway by which aspirin can reduce cancer risk.

Aged↗

PubMed1998

Melanoma arising in nevus spilus.

Nevus spilus is a pigmented skin lesion composed of a pigmented macule on which darker lesions appear at a later stage. There are an increasing number of reports of malignant melanoma occurring within these lesions, leading to greater concern regarding the malignant potential of these lesions. We describe the case of a fatal malignant melanoma arising in a congenital nevus spilus.

Female↗

PubMed1997

Axonal sprouting following incomplete spinal cord injury: an experimental model.

Recovery of function following incomplete spinal cord injury may in part result from growth of new connections by spared descending pathways. It has been difficult to demonstrate such anatomical reorganization with traditional anatomic techniques. This study utilizes an immunocytochemical method to demonstrate axonal growth cones within the lumbar spinal cord in rats recovering from an incomplete midthoracic spinal cord injury. Adult rats underwent subtotal section of the midthoracic cord sparing the left lateral funiculus and a portion of the left ventral funiculus. Light microscope immunocytochemistry was performed on sections of lumbar spinal cord with antibodies to identify sprouting axons. These antibodies were used to determine the distribution of growth cones on both sides of the lumbar spinal cord in experimental and control animals. Growth cones were first observed three days after the spinal cord lesion. Specific labeling, similar in appearance to previous reports of growth cone identification, was apparent within the immediate gray and ventral horns on both sides of the cord. These data support the hypothesis of collateral sprouting distal to the lesion site following incomplete spinal cord injury. It further supports the idea that recovery of function following incomplete spinal cord injury is, in part, mediated by spared descending pathways.

Animals↗

PubMed1996

AIDS prevention in high-risk African American women: behavioral, psychological, and gender issues.

A three-year longitudinal intervention study was implemented to reduce high-risk drug and sexual behaviors in methadone-dependent African American women. Participants were recruited from four inner-city methadone maintenance programs and randomly assigned either to an eight-week peer counseling and leadership training group or to a control group. The 107 trainees and 97 controls completed pretests and posttests at two, four, and seven months. This paper focuses on final data related to the subjects' sexual beliefs, attitudes, knowledge, and behaviors that put them at risk for HIV/AIDS. Reasons for not using condoms are categorized and discussed. Despite the women's awareness of the seriousness of AIDS, perceived powerlessness to negotiate condom use, negative attitudes about the use of condoms, influence of drugs, and unavailablility of condoms interfered with safer sex practices. The inability of education alone to prevent many high-risk sexual behaviors suggests that more serious consideration be given to expanded distribution of condoms as well as needle exchange programs and legalization of illicit drugs.

Acquired Immunodeficiency Syndrome↗

PubMed1996

Dietary modulation of human platelet phenolsulphotransferase activity.

1. The mammalian phenolsulphotransferase enzymes are known to play a major role in both the detoxification and possibly the activation of pre-carcinogenic phenols and aromatic amines. 2. Vegetable cytosol preparations were tested in vitro for their ability to affect the sulphation of two reference compounds (rho-nitrophenol and dopamine, which are selective substrates for the phenol and monoamine forms of phenolsulphotransferase respectively), and to act as substrates for the enzymes in comparison with the same reference compounds. 3. The majority of cytosols greatly decreased (> 80%) the sulphation of either or both the reference compounds. This effect may have been due to either enzyme inhibition or substrate binding. 4. Whereas some of the cytosols were sulphated under the assay conditions, most were not. Additionally, it was found that a cytosol that decreased the sulphation of the two reference compounds was not necessarily poorly sulphated itself. 5. It is concluded that dietary factors have the potential to play a major role in modulating the sulphation detoxification pathway, and have wide ranging implications with regard to adverse drug reactions.

Arylsulfotransferase↗

PubMed1996

Prophylaxis of deep venous thrombosis after total hip arthroplasty by using intermittent compression of the plantar venous plexus.

A randomized, prospective, blinded study comparing the efficacy of prophylaxis of deep venous thrombosis by using (A) heparin-aspirin therapy, (B) intermittent pulsatile pneumatic-pump compression of the plantar venous plexus, or (C) both methods, was conducted in patients undergoing elective total hip replacement arthroplasty. Duplex ultrasonography was obtained in all 75 patients before surgery, at 1 week, and 2 weeks after surgery, to detect the presence or absence of deep venous thrombosis, with venograms confirming all positive results. Five of 25 patients in group A (heparin-aspirin) developed deep vein thrombosis. No deep venous thrombi were detected in groups B or C. One pulmonary embolus was detected in group A. The reduction in detectable deep venous thrombosis by the use of intermittent compression of the plantar venous plexus was significant. Wound drainage was decreased by 2 to 3 days (P < 0.05) in group B. It is concluded that, in this group of 75 consecutive patients, intermittent pulsatile compression of the plantar venous plexus was superior to heparin/aspirin pharmacologic prophylaxis for the prevention of deep venous thrombosis proximal to the calf.

Adult↗

PubMed1995

Perception of AIDS risk and high-risk behaviors in African-American methadone-dependent women.

AIDS poses a particularly serious threat to African-American women who are or have been intravenous drug users. This study evaluated relationships among AIDS knowledge, perceptions of chances of contracting AIDS, and high-risk AIDS behaviors in 102 low-income African-American women from four methadone-maintenance clinics in Baltimore, who volunteered to answer questions about AIDS and their sexual and drug-use behaviors. The participants demonstrated a high level of AIDS knowledge, which was significantly correlated with their perception of likelihood of having the AIDS virus (r = .49, p < .05). However, there was little evidence of avoidance of high-risk sexual behaviors. Despite this knowledge, these data indicate that understanding how the virus is transmitted does not assure a change in behavior. The issue is complicated by the question of how knowledge possessed by individuals relates to their sense of powerlessness or empowerment and the risks and benefits associated with using that knowledge.

Acquired Immunodeficiency Syndrome↗

PubMed1994

Spared descending pathways mediate locomotor recovery after subtotal spinal cord injury.

The location of pathways responsible for locomotor recovery after incomplete spinal cord injury has been studied in adult rats. Animals were allowed to recover from subtotal mid-thoracic cord section which spared left lateral and ventral funiculus fibers. Subsequent lumbar commissurotomy or left thoracic cord hemisection abolished the locomotor recovery. Spared descending fibers passing through the initial incomplete cord lesion appear to mediate locomotor recovery.

Animals↗

PubMed1994

Models for medical practice integration.

Decreased physician income, increased administrative burdens, and interference with the compassionate delivery of high-quality medical care are threatening the independent practice of medicine in solo and small group practices. Many established physicians, and the hospitals with which they relate, are searching for organizational models that, by integrating some or all aspects of their practices, will preserve incomes and reduce regulatory and administrative burdens. This article will describe several "practice integration models," pointing out advantages and disadvantages to physicians in established practices. (Many of the same arguments could be made for physicians new to practice, with different emphasis). The continuum of integration models is shown in figure 1, page 19. The group practice without walls and its two submodels, the independent group practice without walls (IGWW) and the affiliated medical practice corporation (AMPC) are more recent and more effective models and will be covered in depth in the article.

Cost-Benefit Analysis↗

PubMed1993

Physical mapping within the tuberous sclerosis linkage group in region 9q32-q34.

Pulsed-field gel electrophoresis and flow dot-blot analysis have been used to construct a physical map of the q32-q34 region of chromosome 9, where one of the loci responsible for tuberous sclerosis (TSC1) has been mapped by genetic linkage. Five linked groups of markers have been defined by pulsed-field gel electrophoresis. The orientation of these groups and the order of markers within them were determined by hybridization to flow-sorted dot blots derived from a panel of cell lines of chromosome 9 translocations to place probes proximal or distal to each breakpoint. The local map order in 9q32-q34 derived by application of this combination of techniques is as follows: centromere-ALAD-1.3 Mb-ORM/20 kbD9S16-GSN-250 kb-C5-HXB-1.9 Mb-D9S21-AK1-1.4 Mb-SPTAN1-ASS-800 kb-ABL-2 Mb-D9S10/350 Kb/DBH-telomere.

Cell Line↗

PubMed1993

Hypnotic susceptibility, mood state, and cardiovascular reactivity.

In this study we explored the relationship between hypnotic susceptibility measured with the Harvard Group Scale of Hypnotic Susceptibility (HGSHS) and cardiovascular parameters. After assessing their degree of hypnotic susceptibility, we induced 21 female students into happy mood states and into sad mood states. During the mood state induction we monitored blood pressure, heart rate, and cardiac vagal tone continuously. The study demonstrated a strong relationship between hypnotic susceptibility and both cardiac vagal tone and heart rate reactivity. Subjects with lower heart rate and greater vagal tone during baseline and greater heart rate increases during mood induction were more susceptible to hypnosis. Multiple regression analyses indicated that approximately 40% of the individual difference variance of hypnotic susceptibility was accounted for by baseline cardiac vagal tone and heart rate reactivity during mood state. The data demonstrate that autonomic tone, assessed by cardiac vagal tone and heart rate reactivity, are related to hypnotic susceptibility as measured by the HGSHS.

Adult↗

PubMed1992

Collaboration as a strategy for acquired immunodeficiency syndrome prevention.

An eight-session training model used a social interactive framework to combine theoretical and methodological aspects of peer counseling, cross-cultural communication, and transcultural nursing, with a conviction that the participants (volunteers from an ongoing, urban methadone maintenance program) had significant strengths on which to build. The objective was to assist urban, drug dependent black women in taking control of their own lives through collaboration with health care professionals to develop and promote culturally acceptable behavioral alternatives related to reduction of risk for human immunodeficiency virus. The collaborative approach focused on rewards of behavioral change and minimized attention to prevention of negative behaviors, while openly valuing input from the women who are potential health promoters in their own communities. Evaluation of the Peer Counseling Leadership Training Program suggested that the approach facilitated personal risk-reducing behavioral change, improved self esteem, and successfully promoted involvement in community-based prevention efforts.

Acquired Immunodeficiency Syndrome↗

PubMed1992

Strategies for AIDS prevention: leadership training and peer counseling for high-risk African-American women in the drug user community.

A culturally congruent training program to promote HIV risk-reduction behaviors was implemented in a convenient sample of 9 African-American women in an urban methadone treatment program. At each of eight peer counseling and leadership training (PCLT) program sessions, the transmission and prevention of AIDS were discussed while emphasizing enhancement of participants' self-esteem, confidence, and control over high-risk behaviors. The results indicate that support of the women helped develop their sense of purpose and self-worth, reduced sexual and drug use practices associated with risk for HIV and AIDS infection, and promoted assumption of leadership roles and dissemination of accurate AIDS-related information in their communities. It was apparent that knowledge alone does not change behavior if it conflicts with established norms, values, beliefs, and life-styles and that individuals who have a sense of personal control are more willing to explore alternative lower-risk behaviors.

Acquired Immunodeficiency Syndrome↗

PubMed1991

High-performance liquid chromatographic determination of 4,4'-methylenedianiline in human urine.

A method is described for the determination of urinary 4,4'-methylenedianiline (MDA) by high-performance liquid chromatography (HPLC). MDA was extracted from hydrolyzed urine using C18 solid-phase extraction columns. The extract was analyzed by reversed-phase HPLC with electrochemical detection at a cell potential of 0.8 V. The method was very sensitive (detection limit 2.5 micrograms/l) and quantitation using 4,4'-ethylenedianiline as an internal standard correlated well with results by gas chromatography-mas spectrometry. Run-to-run precision (n = 25) averaged 8.9%. In analysis of more than 160 potentially exposed workers, MDA was detected in less than 20% of the urines and concentrations ranged up to 210 micrograms MDA per g of creatinine.

Aniline Compounds↗