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Biomedical subjects

R Marshall

Publications and source records attributed to R Marshall.

At least 91 records · Page 5Linked to original sources
PubMed1995

Sleep apnoea in patients with quadriplegia.

BACKGROUND: This study was undertaken to establish the prevalence of, and the factors contributing towards, sleep disordered breathing in patients with quadriplegia. METHODS: Forty representative quadriplegic patients (time since injury > 6 months, injury level C8 and above, Frankel category A, B, or C; mean (SE) age 35.0 (1.7) years) had home sleep studies in which EEG, EOG, submental EMG, body movement, nasal airflow, respiratory effort, and pulse oximetry (SpO2) were measured. Patients reporting post traumatic amnesia of > 24 hours, drug or alcohol abuse or other major medical illness were excluded from the study. A questionnaire on medications and sleep was administered and supine blood pressure, awake SpO2, spirometric values, height, and neck circumference were measured. RESULTS: A pattern of sustained hypoventilation was not observed in any of the patients. Sleep apnoeas and hypopnoeas were, however, common. Eleven patients (27.5%) had a respiratory disturbance index (RDI, apnoeas plus hypopnoeas per hour of sleep) of > or = 15, with nadir SpO2 ranging from 49% to 95%. Twelve of the 40 (30%) had an apnoea index (AI) of > or = 5 and, of these, nine (75%) had predominantly obstructive apnoeas-that is, > 80% of apnoeas were obstructive or mixed. This represents a prevalence of sleep disordered breathing more than twice that observed in normal populations. For the study population RDI correlated with systolic and diastolic blood pressure and neck circumference. RDI was higher in patients who slept supine compared with those in other postures. Daytime sleepiness was a common complaint in the study population and sleep architecture was considerably disturbed with decreased REM sleep and increased stage 1 non-REM sleep. CONCLUSIONS: Sleep disordered breathing is common in quadriplegic patients and sleep disturbance is significant. The predominant type of apnoea is obstructive. As with non-quadriplegic patients with sleep apnoea, sleep disordered breathing in quadriplegics is associated with increased neck circumference and the supine sleep posture.

Adult↗
PubMed1994

An evaluation of the relationship between self-report and biochemical measures of environmental tobacco smoke exposure.

To evaluate the relationship between self-reported exposure to environmental tobacco smoke and saliva cotinine concentrations, we studied 186 nonsmokers. Each participant completed an exposure questionnaire, kept a daily exposure diary for 7 days, and provided a saliva sample for cotinine analysis. Salivary cotinine concentrations were measured using gas chromatography/mass spectrometry. Of the volunteers, 30% lived with one or more smokers, and 84% were regularly exposed to smokers at work. Eighty-three percent of the volunteers had detectable saliva cotinine concentrations (> or = 0.5 ng/ml) (median = 1.1; range = 0.5-7.4 ng/ml). Cotinine concentrations were related to exposure in the household and at the workplace. Volunteers who lived with smokers had significantly higher cotinine levels (median = 1.0; range = < 0.5-7.4 ng/ml) than those who did not (median = < 0.5; range = < 0.5-4.7 ng/ml). Volunteers who reported regular exposure at work had higher cotinine levels (median = 0.8; range = < 0.5-7.4 ng/ml) than those who did not (median = < 0.5; range = < 0.5-3.0 ng/ml). Cotinine concentrations were predicted by a regression equation that included the number of smokers at home and work and the number of minutes of exposure recorded in the daily diary (r2 = 0.29).

Adolescent↗
PubMed1994

A three-dimensional kinematic method for determining the effectiveness of arm segment rotations in producing racquet-head speed.

The contribution that a segment's anatomical rotations make to racquet-head speed depends on both the segment's angular velocity and the instantaneous position of the head of the racquet with respect to the segment's axes of rotation. Any analysis of racquet swing technique that does not consider both of these factors simultaneously is, at best, incomplete. With this in mind, a three-dimensional kinematic method was developed to determine the effectiveness of the anatomical rotations of the upper arm, forearm, and hand in producing racquet-head speed. The method entailed developing a system of vector equations for three-dimensional upper limb rotations that used displacement histories of 10 selected landmarks as input. The required three-dimensional displacement histories were obtained using three cine cameras and the DLT approach. To test the diagnostic capabilities of the method, a tennis serve was selected for analysis. For the player and serve analyzed, the greatest contribution to racquet-head speed at impact was produced by internal rotation of the upper arm (8 m s-1). Forearm pronation, although exhibiting the fastest rotation at impact (24 rad s-1), ranked only fourth in terms of its contribution (4 m s-1) to racquet-head speed. To test the performance of the method, a comparison was made between the racquet-head speed measured directly from film and the racquet-head speed computed by summing all of the individual segment contributions to speed commencing at the start of forward swing and ending at ball contact. The results indicate that the method can successfully determine the individual contributions that the different anatomical rotational velocities of the arm segments make to the measured instantaneous racquet-head speed.

Algorithms↗
PubMed1994

Genotoxicity studies with chloroethane.

In a recent 2-year inhalation study with F344 rats and B6C3F1 mice conducted as part of the U.S. National Toxicology Program (NTP, 1989), chloroethane (ECl) at an exposure concentration of 15,000 ppm induced a high incidence of endometrial uterine carcinomas only in female mice but not in rats, leading to the conclusion of "clear evidence of carcinogenicity" for the mouse. In order to elucidate whether a genotoxic effect may be a critical factor for the carcinogenicity of ECl in the mouse, we have performed three genotoxicity tests: (1) in vitro HPRT test with CHO cells according to a specially developed gas protocol, (2) in vivo/in vitro UDS with female B6C3F1 mice at an exposure concentration of 25,000 ppm (6 h/day, 3 days), (3) in vivo micronucleus assay with male and female B6C3F1 mice exposed to 25,000 ppm ECl according to the same schedule. In the in vitro HPRT test a mutagenic potential of ECl was detected in the presence as well as in the absence of S9 mix. In contrast, both in vivo test systems failed to detect any indications of genotoxicity of chloroethane at an exposure concentration even higher than that of the NTP study. It is suggested that in vivo the genotoxic potential of ECl is so low that an assumed genotoxic damage is below the detection limit of the test systems used. This leads to the conclusion that genotoxicity may not be a key factor in the induction of the uterine carcinomas in the B6C3F1 mouse.

Animals↗
PubMed1993

Low follicular oestrogen levels in New Zealand women consuming high fibre diets: a risk factor for osteopenia?

AIMS: To study effects of anthropometry, diet and exercise on plasma 17 beta-oestradiol concentrations in healthy premenopausal women. METHODS: Fifty-five healthy female volunteers aged 19-29 (Mean (SD) = 22.2 (2.6) years) were studied. Anthropometric measurements were made, food intakes were estimated using a food frequency questionnaire, physical activity was assessed, menstrual histories were taken and blood 17 beta-oestradiol values were measured in the follicular and luteal phases of the menstrual cycle. RESULTS: Adiposity and dietary fat intake did not influence circulating plasma 17 beta-oestradiol but dietary fibre intake was negatively correlated with both follicular (r = -0.43, p < 0.001) and luteal (r = -0.28, p < 0.05) 17 beta-oestradiol concentrations. Follicular oestradiol values were abnormally low in 53% of the population. Subjects with high fibre intakes (> or = 25 g fibre daily) had significantly lower concentrations of 17 beta-oestradiol in the follicular phase of the menstrual cycle (p < 0.01). Physical activity was similar in groups consuming high and low fibre diets. Subjects with oligomenorrhoea or amenorrhoea (n = 7) had higher fibre intakes/energy (p < 0.05) than subjects with eumenorrhoea (n = 48). CONCLUSION: Our study suggests that healthy New Zealand women of premenopausal age have lower 17 beta-oestradiol levels on high fibre diets than on low fibre diets. Because hypoestrogenism is a known risk factor for osteoporosis we propose that high fibre intakes may influence bone mass adversely and be a risk factor for osteoporosis. The effects of high fibre intakes on bone mass warrant further investigation.

Adult↗
PubMed1993

Reproductive and thyroid effects of low-level polychlorinated biphenyl (Aroclor 1254) exposure.

As little information is available on the adverse effects of polychlorinated biphenyls (PCBs) on the reproductive system of the male rat, the current study was conducted to evaluate the effects of subchronic administration of the PCB mixture Aroclor 1254 on testicular gamete production and endocrine function. The thyroid hormone thyroxine (T4), which is critical for reproduction and development, was also measured because of the well-documented effects of PCBs on this hormone. Weanling (31-day-old) male Fischer rats were administered 0, 0.1, 1, 10, or 25 mg/kg/day Aroclor 1254 by gavage for 5, 10, or 15 weeks and necropsied. The hormones testosterone (T) and thyroxine were measured in the serum, and body weight and weights of the liver, kidney, testes, seminal vesicle plus coagulating gland, cauda epididymides, and pituitary were taken. At 10 and 15 weeks, testicular interstitial fluid (IF) was collected and T concentration in the IF was measured. Sperm motility was measured from a caudal sperm sample and sperm numbers in the testis and cauda epididymis were determined. In addition, tissues were examined microscopically for histopathological alterations. In the high-dose group, body, seminal vesicle, cauda epididymal, and pituitary weights were depressed at 10 and 15 weeks and cauda epididymal sperm numbers were reduced after 15 weeks of dosing. In contrast, testes weights, testicular sperm numbers, sperm motility, and serum and testicular testosterone levels were unaffected, even in the highest dose group (25 mg/kg/day). Aroclor 1254 administration produced histological alterations in the liver and kidney at doses of 1.0 mg/kg/day and above.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Prognostic factors and long-term survival in endometrial adenocarcinoma with cervical involvement.

The clinical, surgical, and histopathologic data from 202 patients with endometrial adenocarcinoma with cervical involvement are presented. One hundred fifty-one (75%) had histopathologically confirmed cervical involvement at the time of their definitive surgery, while in 51 (25%) no cervical involvement was conclusively identified. The 5-year actuarial survival for patients with true surgical stage II endometrial carcinoma (N = 24) was 76%. Extrauterine disease was documented in 32% (27/84) of patients in which the primary treatment modality was surgical. The 5-year actuarial survival was 65% for all patients with clinical surgical stage II disease. There appeared to be a survival advantage for patients treated by radical surgery as compared with more conventional treatments, especially in patients with numerous high-risk factors. The subgroup of patients (N = 53) having tumor grossly involving the cervix had a 5-year survival of 48%. In this subgroup of patients, radical hysterectomy offered improved 5-year survival over more traditional forms of treatment, particularly compared with simple hysterectomy or combined treatment with radiation and surgery. Multivariate analysis positively correlated myometrial invasion, grade, uterine serosal involvement, lower uterine segment involvement, adnexal metastasis, pelvic metastasis, aortic node metastasis, and peritoneal cytology, with disease-free survival. Clinical and surgical findings correlated poorly; therefore, primary surgical evaluation is recommended when possible.

Adenocarcinoma↗
PubMed1993

Animal models of early osteoarthritis: their use for the evaluation of potential chondroprotective agents.

Medial meniscectomy was undertaken in adult merino sheep and after 16 weeks exercise each group was administered five weekly intra-articular injections of saline, pentosan polysulphate (PPS), hyaluronic acid (HA) or a combination of PPS + HA. Gait analysis and x-rays were undertaken before and after drug treatment. At sacrifice (26 weeks), joints were examined for gross pathological and histochemical changes. Only the PPS-treated group showed an improvement in gait, with low radiological and histology scores. The HA-treated group showed similar but less significant changes to these parameters.

Animals↗
PubMed1993

The effects of intraarticular administration of hyaluronan in a model of early osteoarthritis in sheep. I. Gait analysis and radiological and morphological studies.

Using a model of early osteoarthritis (OA) induced in ovine joints by medial meniscectomy, the intraarticular effects of two hyaluronic acid (HA) preparations (AHA and DHA) were investigated. DHA was an HA preparation with an average molecular weight (MW) of approximately 2.0 x 10(6) d, and AHA had a MW of approximately 8 x 10(5) d. Animals (n = 5) were injected intraarticularly with 1 mL (10 mg/mL) of either HA preparation once a week for 5 weeks beginning 16 weeks after initiation of arthropathy. Meniscectomized, saline (1.0 mL)-injected animals (n = 5) and nonoperated sheep (n = 5) were used for controls. Force-plate analysis of gait and radiographic changes in joints were evaluated in these groups before and after intraarticular treatment. At necropsy, cartilage gross morphology, osteophyte development, and cartilage histopathology were examined. Meniscectomized joints were characterized by erosions and fissuring of cartilage of the medial compartment with areas of decreased matrix staining for proteoglycans. Osteophytes were present at the medial joint margins. Saline-treated meniscectomized animals showed reduced loading of the operated limb using the force plate. Force-plate analysis of walking animals before and after treatment with either AHA or DHA indicated some normalization of joint loading. However, osteophyte scores for meniscectomized joints injected with AHA and DHA were higher after treatment than those of the corresponding saline-treated group. Although the gross cartilage damage was lower than in saline-treated controls for both the HA-treated groups, the histological scores did not support this conclusion. Indeed, the tibial score for the DHA group was higher than for the AHA group (P < .05). These studies confirmed previous reports that meniscectomy of sheep stifle (knee) joints resulted in matrix changes similar to those described for early OA in humans. Both HA preparations appeared to improve gait, suggesting decreased lameness. Increased joint loading associated with gait improvement may account for the higher osteophyte scores in the treated groups. However, cartilage damage with DHA was found to be higher than when the lower-MW HA preparation (AHA) was used.

Animals↗
PubMed1993

Attention deficit-hyperactivity disorder and asymmetry of the caudate nucleus.

The neurologic basis of attention deficit-hyperactivity disorder (ADHD) is poorly understood. Based on previous studies that have implicated metabolic deficiencies in the caudate-striatal region in ADHD, we employed magnetic resonance imaging to investigate patterns of morphology of the head of the caudate nucleus in normal and ADHD children. In normal children, 72.7% evidenced a left-larger-than-right (L > R) pattern of asymmetry, whereas 63.6% of the ADHD children had the reverse (L < R) pattern of asymmetry of the head of the caudate nucleus. This reversal of normal asymmetry in ADHD children was due to a significantly smaller left caudate nucleus. The reversal in asymmetry of the head of the caudate was most notable in ADHD males. These results suggest that normal (L > R) morphologic asymmetry in the region of the caudate nucleus may be related to asymmetries observed in neurotransmitter systems implicated in ADHD. The behavioral symptoms of ADHD may reflect disinhibition from normal levels of dominant hemispheric control, possibly correlated with deviations in asymmetric caudate-striatal morphology and deficiencies in associated neurotransmitter systems.

Acetyltransferases↗
PubMed1993

Detection of human papillomavirus DNA in oral verrucous carcinoma by polymerase chain reaction.

Archival tissue biopsies of 17 cases of oral verrucous carcinoma were tested for human papillomaviruses by polymerase chain reaction followed by DNA slot-blot hybridization. Sections of the biopsies were also tested by in situ DNA hybridization with biotin-labeled probes for human papillomavirus types 6/11, 6/18, and 31/33/35. Using polymerase chain reaction, human papillomavirus DNA was detected in seven of 17 cases (41%). Slot-blot hybridization of the amplification products identified human papillomavirus type 6 in two cases, type 11 in four cases, and both types 6 and 11 in one case of oral verrucous carcinoma. In situ hybridization confirmed the presence of human papillomavirus type 6/11 DNA in tumor cell nuclei for each of the cases which tested positive by polymerase chain reaction and was negative in the remaining 10 cases. We conclude that human papillomavirus types 6 and 11 are frequently present in cases of oral verrucous carcinoma.

Adult↗
PubMed1992

Suramin: a selective inhibitor of purinergic neurotransmission in the rat isolated vas deferens.

The effects of the putative P2 purinoceptor antagonist suramin on contractile responses of the rat isolated vas deferens to electrical field stimulation and exogenously applied drugs (alpha,beta-methylene ATP and noradrenaline) were investigated. Suramin was devoid of agonist activity in the rat vas deferens. The response of the vas deferens to single pulse field stimulation was characteristically biphasic with a large first component peaking between 260-300 ms after the stimulus followed by a second smaller component peaking at about 650 ms post-stimulus. Suramin (100 nM-1 mM) selectively impaired the first, purinergic phase of the response to single pulse field stimulation but was without effect on the second, noradrenergic component. The response of the vas deferens to trains of electrical field stimuli (10 Hz for 10 s) was also biphasic. Suramin (1 microM-1 mM) reduced the first (less than 1 s) phase of the response by 30%, the second (greater than 5 s) plateau phase by 50% and inhibited the intermediate (2-4 s) phase by 80%. Dose-contact periods of 20 or 30 min respectively were sufficient to achieve equilibration of the inhibitory effects of suramin against the responses to single pulse field stimulation or trains of pulses. Following 30 min incubation with 1 mM suramin, the remaining first and second phase components of the response to trains of pulses were impaired and subsequently abolished by the alpha 1-adrenoceptor antagonist WB4101 establishing their noradrenergic origin. Suramin (300 microM) abolished responses of the vas deferens to alpha,beta-methylene ATP but was without effect on those to noradrenaline. Suramin (30 microM) induced a rightward shift in the concentration-response relationship to alpha,beta-methylene ATP that was associated with a significant 40% increase in the maximum response, but did not modify responses to noradrenaline. The inhibitory effects of suramin (3-300 microM) on responses of the vas deferens to approximate EC50 concentrations of alpha,beta-methylene ATP were reversible on repeated washout for 40-60 min. These results reveal suramin to be a useful pharmacological tool for the study of purinergic neurotransmission in rodent vasa deferentia.

Adenosine Triphosphate↗
PubMed1992

Distinct syndromes of hemineglect.

Hemineglect was assessed in 34 patients with right-hemisphere stroke using a letter-cancellation task and a line bisection task. No significant correlation (r = .39) was found between scores on the two tests. Ten patients who showed neglect on the cancellation task but performed normally on line bisection had frontal or deep lesions. Eleven patients with posterior lesions deviated rightward on line bisection; several of these had minimal or no cancellation deficit. A nonmotor task involving judgment of a bisected line was also performed abnormally by six patients with line bisection shift, suggesting that such shift does not result from a motor response asymmetry. We propose that separable components of the neglect syndrome may be associated with damage to discrete areas of the nondominant hemisphere.

Adult↗
PubMed1992

Gonadal effects of fetal exposure to the azo dye congo red in mice: infertility in female but not male offspring.

The present study describes the relationship between gonadal agenesis and fertility in male and female mice exposed in utero to the diazo dye Congo red (CR). Maternal CR treatment inhibited testicular and ovarian function in the offspring after oral administration of 1 or 0.5 g/kg/day on Gestational Days 8-12. The testes of male offspring from CR-exposed dams were small in size and contained hypospermatogenic seminiferous tubules. However, despite the fact that testis weight was reduced by more than 70% in some males, they displayed normal levels of fertility when mated to untreated females for over 10 months. In contrast, female offspring from CR-exposed dams produced only about half as many litters and pups as the control pairs did under long-term mating conditions. Histological examination of the ovaries revealed that subfertility was correlated with ovarian atrophy. Females lacking maturing follicles were considerably less productive (1.3 litters and 11.5 pups) than treated females with histologically normal ovaries (7.1 litters and 78.1 pups). In summary, prenatal exposure to the dye CR affects the gonads of both male and female offspring, but only the female offspring display reduced fertility.

Animals↗