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Biomedical subjects

H Wright

Publications and source records attributed to H Wright.

At least 55 records · Page 3Linked to original sources
PubMed1994

Mapping and characterization of the DQ subregion of the ovine MHC.

A map of the ovine MHC class II DQ subregion has been constructed from overlapping cosmid clones. This region consists of two loci linked on a linear tract of 130 kb DNA. Each locus consists of a DQA and a DQB gene in a tail-to-tail orientation. The genes in each locus are transcribed but only those designated DQ1 express class II molecules at the surface of mouse L cells following DNA-mediated gene transfection. The DQA1 and DQB1 genes are separated by 11 kb while the DQA2 and B2 genes are 25 kb apart. The loci are separated by 22 kb.

Animals↗
PubMed1994

Survival following intentional massive overdose of 'Ecstasy'.

A case of intentional overdose with 18 'Ecstasy' tablets is described. 'Ecstasy' is a semi-synthetic hallucinogenic amphetamine and acute adverse reactions follow from the effects of sympathetic stimulation. To our knowledge this is the first reported case of massive intentional overdose reported in the literature.

Adult↗
PubMed1994

The fibre type composition of the rabbit latissimus dorsi muscle.

The fibre type distribution has been mapped in the latissimus dorsi muscle of the Dutch rabbit. Using the myosin ATPase stain, a distinct border was found to run in a cranial to caudal direction, which effectively divided the muscle into 2 segments of different fibre type proportions. Although both segments contained mostly fast twitch fibres, the medial areas were found to contain approximately 10-20% slow (i.e. type I) fibres while the lateral portions contained very few, if any, slow fibres. Significantly fewer type IIa fibres were also found in the lateral areas of the muscle. These histochemical findings were confirmed by the use of the reverse transcriptase polymerase chain reaction, which demonstrated that more messenger RNA of the slow myosin heavy chain was found in the medial regions compared with the lateral segment. These results demonstrate the importance of choosing well defined sampling sites when evaluating regimes designed to transform this heterogeneous muscle for use in subsequent myoplasty procedures.

Animals↗
PubMed1993

The effect of evening bright light in delaying the circadian rhythms and lengthening the sleep of early morning awakening insomniacs.

Past studies have predicted that early morning awakening insomnia is associated with advanced or early circadian rhythms. Because bright light stimulation in the evening can delay the phase of circadian rhythms, we tested its effects on nine (4 females, 5 males) early morning awakening insomniacs. Their sleep was evaluated with wrist actigraphy and their temperature and melatonin circadian rhythms were measured in constant routine procedures. In the initial evaluation, the temperature rhythm phase positions of these insomniacs did appear to be earlier than normal. The subjects were then exposed to bright light stimulation (2,500 lux) from 2000 to 2400 hours on two consecutive evenings. Following the evening bright light treatment, temperature rhythm phase markers were delayed 2-4 hours and melatonin phase markers were delayed 1-2 hours. Sleep onset times were not changed but the mean final wake-up time was delayed from 0459 hours to 0611 hours, resulting in a mean increase of total sleep time of > 1 hour. This pilot study suggests that evening bright light stimulation may be an effective nondrug treatment for early morning awakening insomnia.

Body Temperature↗
PubMed1993

Liver biopsy. Its safety and complications as seen at a liver transplant center.

Liver biopsy is a frequently utilized diagnostic tool at a liver transplant center. It is occasionally utilized prior to OLTx to determine whether or not a potential recipient either has tumor or a disease process that has some chance of spontaneous recovery without OLTx. Following OLTx, it is often utilized to determine the need to alter a recipient's immunosuppression regimen or gauge the response to a recent change in immunosuppression. At the University of Pittsburgh Medical Center, adult liver transplant patients have been biopsied using 3 different techniques based upon the physician's (Tru-cut needle) or surgeon's (suction needle) personal choice and whether or not it has been the intent of the biopsy to obtain tissue from a focal lesion within a liver. In the latter cases, ultrasound guidance and an automated biopsy needle are used. In the former, either a suction-type needle (Jamshidi) or a cutting needle (Tru-cut) has been used. During the period between January 1, 1989, and December 31, 1991, a total of 12,750 liver biopsies have been done on patients admitted to the adult transplant service at this institution. Of these, 8500 were performed with a suction needle, 4195 were performed using a cutting needle, and 55 were performed under ultrasound guidance using an automated cutting needle. A total of 26 major complications occurred--19 with the suction needle (0.22%); 6 with the cutting needle (0.14%), and 2 using ultrasound guidance and an automatic cutting needle (3.6%). Nine of these 26 complications required surgical intervention consisting of a thoracotomy or laparotomy; 4 required the insertion of a chest tube and two required hepatic artery embolization. Based upon these data obtained at a large transplant center, it can be concluded that, in general: (1) a liver biopsy can be done safely in liver transplant recipients; (2) an overall low rate of major complications occurs varying from 0.1 to 3.6% depending upon the type of needle and other circumstances relating to the biopsy procedure; (3) complications, when they occur, are morbid and often necessitate either additional surgical or interventional radiologic procedures.

Biopsy, Needle↗
PubMed1993

Validity of 20-MST for predicting VO2max of adult Singaporean athletes.

This investigation compared the results of direct and indirect measurements of maximum oxygen uptake (VO2max) of an Asian population. Twenty subjects (16 male, 4 female), all of whom were physical education students, were assessed directly using laboratory treadmill running to determine VO2max. The indirect estimation of VO2max was obtained using a modified form of the Leger and Lambert 20-m multistage shuttle run test (20-MST). Heart rates were recorded throughout both tests. Pearson product moment correlations confirmed test-retest reliability for both direct and indirect measurements (r = 0.90 and r = 0.91 respectively). Differences for test-retest were found to be not significant. No differences were found between the maximal heart rate responses of the subjects for the direct and indirect tests. Of the subjects 75% had a lower predicted VO2max value (P < 0.01) compared with results gained by direct measurements when the Ramsbottom norms for the 20-MST were used. The reasons for this difference could be due to the different racial groups used as subjects, the climatic conditions in Singapore, or the small sample size. In order for the 20-MST test to be considered a valid measure of aerobic fitness in Singapore with an Asian population further study is recommended.

Adult↗
PubMed1993

Transjugular intrahepatic portosystemic shunt in the management of variceal bleeding: indications and clinical results.

BACKGROUND: Transjugular intrahepatic portosystemic shunt (TIPS) has proved to be a successful bridge to liver transplantation in the management of variceal bleeding. The safety and ease of this technique has now challenged standard surgical approaches to portal hypertension. To define the role of TIPS, we prospectively studied patients undergoing this procedure for variceal bleeding and/or ascites. METHODS: From September 1991 to September 1992, 45 patients entered a protocol that included assessment of liver chemistries, ammonia levels, coagulation profiles, liver synthetic function by caffeine-antipyrine clearance, ultrasonographic evaluation of hepatic and portal veins, portogram and direct measurement of portal vein pressures, upper endoscopy, computed tomography for liver volume and ascites, and formal neuropsychiatric evaluation. These studies were repeated at 3-month intervals or more frequently if bleeding or complications occurred. RESULTS: Technical success and control of bleeding were achieved in all patients with only three (7%) variceal rebleeds from recurrent portal hypertension. Complete and permanent control of clinical ascites was noted in all patients with this complication. Five of six deaths occurred from sepsis and multiorgan failure in intensive care unit-bound patients with Child class C liver disease. No serial changes were noted in liver chemistries; however, progressive loss of liver volume and prolongation of caffeine-antipyrine clearance was observed in most patients. In addition, hepatic vein stricture or shunt stenosis seen in nine patients (20%) required TIPS revision, whereas the frequent appearance of symptomatic encephalopathy was a main indication for transplantation in 11 of 14 patients. CONCLUSIONS: TIPS successfully controls variceal bleeding and may serve as a novel approach to control of diuretic resistant ascites. The uncertain long-term patency and progressive decline in synthetic function emphasize the importance of initiating proper trials comparing TIPS with other management strategies before indiscriminant use of this technique is seen.

Ascites↗
PubMed1992

Intestinal transplantation in composite visceral grafts or alone.

Under FK 506-based immunosuppression, the entire cadaver small bowel except for a few proximal and distal centimeters was translated to 17 randomly matched patients, of whom two had antigraft cytotoxic antibodies (positive cross-match). Eight patients received the intestine only, eight had intestine in continuity with the liver, and one received a full multivisceral graft that included the liver, stomach, and pancreas. One liver-intestine recipient died after an intestinal anastomotic leak, sepsis, and graft-versus-host disease. The other 16 patients are alive after 1 to 23 months, in one case after chronic rejection, graft removal, and retransplantation. Twelve of the patients have been liberated from total parenteral nutrition, including all whose transplantation was 2 months or longer ago. The grafts have supported good nutrition, and in children, have allowed growth and weight gain. Management of these patients has been difficult and often complicated, but the end result has been satisfactory in most cases, justifying further clinical trials. The convalescence of the eight patients receiving intestine only has been faster and more trouble free than after liver-intestine or multivisceral transplantation, with no greater difficulty in the control of rejection.

Adult↗
PubMed1992

Expression and characterization of ovine major histocompatibility complex class II (OLA-DR) genes.

Previous work made use of nucleic acid probes corresponding to different subtypes of the class II regions of the human and murine major histocompatibility complex (MHC) to isolate seven different alpha and 24 different beta genes of the ovine MHC from two cosmid libraries. In an attempt to identify pairs of alpha and beta genes capable of cell surface expression, all permutations of alpha and beta genes were in turn transfected into mouse L-cells. Two pairs of alpha and beta genes co-expressed and stable ovine MHC class II L-cell lines were developed. The expressed alpha genes had previously been defined as DR-alpha homologues (DRA) by differential Southern hybridization to human subtype specific class II probes. The expressed ovine beta genes were also assigned as ovine DR-beta homologues (DRB) on the basis of their sequence having a higher degree of similarity with human DRB than any other subtype. A total of eight out of 23 anti-sheep class II specific monoclonal antibodies were typed OLA-DR specific by FACScan analysis using the L-cell lines.

Amino Acid Sequence↗
PubMed1991

Class II major histocompatibility complex genes of the sheep.

The class II genes of the sheep major histocompatibility complex (MHC) have been cloned from two unrelated heterozygous sheep into cosmid vectors. By restriction mapping and hybridization with a number of class II probes of human and mouse origin, the cloned genetic material has been assigned to seven distinct alpha genes, 10 distinct beta genes and 14 beta-related sequences. It was difficult to identify homologues of specific HLA class II genes because of a tendency for the ovine genes to cross-hybridize between HLA probes representing different loci. Such cross-hybridization was especially marked among the beta genes. While DQ and DR homologues have been tentatively identified by several criteria, no genes corresponding to DP have been identified. Cosmids containing class II alpha and beta genes have been transfected into mouse LTK- cells, and surface expression of a sheep class II molecule has been obtained.

Animals↗
PubMed1991

Vocal fold contact area patterns in normal speakers: an investigation using the electrolaryngograph interface system.

This study investigates patterns of vocal fold movement in normal speakers. With the use of new computer software, laryngograph (Lx) waveforms from 100 normal speakers were examined. Specifically, four phases of the Lx waveform were observed and measured. These were then compared on both an interpersonal and intrapersonal basis. The results indicated that four phases were clearly identifiable in almost all subjects and that measurements of the closure and closed phases showed a high degree of consistency. The opening and open phases were more variable. In addition the onset and offset patterns of phonation were observed. Clear patterns were identified, consistent between speakers. The results are discussed with reference to the degree of consistency that can be expected in the vocal fold movement of normal speakers.

Adult↗
PubMed1990

Deafness and immediate memory for pictures: dissociations between "inner speech" and the "inner ear"?

Born-deaf, orally trained youngsters were examined on two tasks of immediate memory for pictures of objects. The aim was to investigate the extent of speech coding for pictures in immediate memory in a developmental context. The deaf, unlike young hearing children, did not use picture-name rhyme spontaneously as a cue to recall in a paired association task. Nevertheless, they were just as sensitive as reading age-matched hearing controls to spoken word length in recalling pictures by name. This might mean that the deaf use articulatory rehearsal in some immediate memory tasks, but this leads to a paradoxical conclusion. What could "inner speech" in the deaf be for, if it fails to affect their "inner ear" by inducing rhyme sensitivity in the paired associate task? This paradox is discussed in relation to distinctions between covert and overt use of memory cues in the paired recall task and to possible sources of the word length effect in young hearing (8-9 years old) and deaf subjects.

Adolescent↗
PubMed1990

Effectiveness of alprazolam in the treatment of chronic pain: results of a preliminary study.

One hundred chronic pain patients were begun on alprazolam, 1.5 mg/day. No other medication changes or therapeutic interventions were made. Sixteen patients were lost to follow-up and 1 oncology patient died. Of the 83 patients who were evaluated at 12 weeks, 61 (73.5%) showed improvement, and only 5 had discontinued the medication because of side effects. The average score of all patients had decreased from 3.6 to 2.2 on a verbal analog scale that rated pain severity from 0 to 5. There was no difference in response among the various diagnostic groups represented in the study population.

Alprazolam↗