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Biomedical subjects

S Harris

Publications and source records attributed to S Harris.

At least 145 records · Page 8Linked to original sources
PubMed1995

Epidemiological studies on intestinal helminth parasites of rural and urban red foxes (Vulpes vulpes) in the United Kingdom.

An epidemiological study of intestinal helminths in 843 foxes (Vulpes vulpes) from southern England revealed the presence of 13 parasite species: five nematodes--Toxocara canis (prevalence 55.9%), Toxascaris leonina (1.5%), Uncinaria stenocephala (68.0%), Trichuris vulpis (0.5%) and Capillaria aerophila (0.2%); four cestodes--Taenia pisiformis (13.8%), Taenia hydatigena (2.5%), Echinococcus granulosus (0.1%) and Dipylidium caninum (3.8%); two trematodes--Brachylaima recurva (2.9%) and Cryptocotyle lingua (2.3%); two acanthocephalans--Prosthorhynchus transversus (0.7%) and Macracanthorhynchus catulinus (0.1%). Trichuris vulpis, Brachylaima recurva, Macracanthorhynchus catulinus and Prosthorhynchus transversus are new host records for the UK. Results are discussed with reference to variations in the diets of urban and rural foxes and to their potential as reservoir hosts for helminths of medical and veterinary importance.

Animals↗
PubMed1995

The effects of cytokines and growth factors on osteoblastic cells.

In this short review, some regulatory mechanisms that are involved in the control of normal bone formation are proposed, based on several in vivo and in vitro models our group has utilized recently to study osteoblast differentiation and mineralized bone matrix formation. Of course, these proposals must be assessed in the light of the limitations of the models, which probably represent a simplification of the complex and different ways in which normal mammalian bone is formed at different sites. Nevertheless, it is likely that the same general types of control mechanisms are active in each of the different types of bone formation. In adult humans, bone formation predominantly occurs by remodeling, the process by which bone which has recently been resorbed by osteoclasts is replaced by teams of osteoblasts. Other types of bone formation such as endochondral bone formation and appositional bone formation are also important, particularly during growth and adolescence. The end results of each of these processes are the same, namely a complex mineralized proteinaceous bone matrix. These processes are modulated by systemic hormonal influences, which are particularly important with respect to pituitary hormones and sex steroids during growth and adolescence, and by local cellular microenvironmental differences. The former will not be discussed here. Rather, we will concentrate on the local events and factors which are likely involved in the bone formation process occurring during normal bone remodeling.

Adult↗
PubMed1995

A yeast DnaJ homologue, Scj1p, can function in the endoplasmic reticulum with BiP/Kar2p via a conserved domain that specifies interactions with Hsp70s.

Eukaryotic cells contain multiple Hsp70 proteins and DnaJ homologues. The partnership between a given Hsp70 and its interacting DnaJ could, in principle, be determined by their cellular colocalization or by specific protein-protein interactions. The yeast SCJ1 gene encodes one of several homologues of the bacterial chaperone DnaJ. We show that Scj1p is located in the lumen of the endoplasmic reticulum (ER), where it can function with Kar2p (the ER-lumenal BiP/Hsp70 of yeast). The region common to all DnaJ homologues (termed the J domain) from Scj1p can be swapped for a similar region in Sec63p, which is known to interact with Kar2p in the ER lumen, to form a functional transmembrane protein component of the secretory machinery. Thus, Kar2p can interact with two different DnaJ proteins. On the other hand, J domains from two other non-ER DnaJs, Sis1p and Mdj1p, do not function when swapped into Sec63p. However, only three amino acid changes in the Sis1p J domain render the Sec63 fusion protein fully functional in the ER lumen. These results indicate that the choice of an Hsp70 partner by a given DnaJ homologue is specified by the J domain.

Amino Acid Sequence↗
PubMed1995

Expression of the rat, S-100-related, calcium-binding protein gene, p9Ka, in transgenic mice demonstrates different patterns of expression between these two species.

p9Ka (also known as mts1/18A2/calvasculin/CAPL) is a member of the S-100-related family of small, calcium-binding proteins. Previous studies suggest apparent discrepancies between the expression of the p9Ka gene in rat, mouse, and human tissues. Here we demonstrate that the natural p9Ka gene is expressed at lower levels in mouse than in rat, and that, in mouse but not in rat, p9Ka mRNA is more highly expressed in cells of lymphoid origin. Transgenic mouse strains express rat-p9Ka transgenes in a gene copy-number-dependent manner. The rat p9Ka transgene mRNA shows the same tissue distribution in several lines of transgenic mice, a distribution that is characteristic of the rat, from which the transgenes were derived. These results show that there is a difference in the pattern of expression of the same gene in two closely related species, and that the pattern of expression found in rat is specified by the DNA in the rat gene itself.

Amino Acid Sequence↗
PubMed1995

Expression of beta 3-adrenoceptor mRNA in rat brain.

The reverse transcription/polymerase chain reaction was used to demonstrate beta 3-adrenoceptor mRNA in rat brain regions. Levels were highest in hippocampus, cerebral cortex and striatum and lower in hypothalamus, brainstem and cerebellum.

Animals↗
PubMed1995

Effect of positive heel inclination on posture.

Millions of women wear high heels on a daily basis; however, few studies have analyzed the changes high heels (positive heel inclination) have on posture. The purpose of this study was to determine whether positive heel inclination changed the postural alignment of the head, spine, pelvis, and knees. Fifteen female college students ((mean age = 22.7, SD = 3.7 years) had sagittal plane angles measured for the cervical spine, thoracic spine, lumbar spine, sacral spine, and knee joints in addition to anterior/posterior displacements of the head and pelvis. All variables were assessed by a Metrecom Skeletal Analysis System, a three-dimensional electrogoniometer. Six randomized trials, three at zero heel inclination and three at 5 cm positive heel inclination, were measured. Analysis of variance results indicated positive heel inclination of subjects brought about significantly lower anterior pelvic tilt, lumbar lordosis, and sacral base angles when compared with zero heel inclination (p < .01). Clinically, patients with low back pain may be affected by high heel usage because of the reduction of the normal lumbar lordosis.

Adult↗
PubMed1995

Postural control and vestibular function in patients selected for cochlear implantation.

Postural control and vestibular and eye motor function were evaluated in 7 postlingually deaf patients before cochlear implantation as vibration toward the calf muscles or galvanic electrical stimulation of the vestibular nerves perturbed stance. The patients were compared with 21 control subjects. Vibration-induced bodysway was increased in the patients compared to the normals. Galvanic stimulation induced a bodysway that was not significantly different from that of the control group suggesting that the patients selected for cochlear implantation, and with otherwise reduced postural control, are sensitive to electrical stimulation of the vestibular nerve. This finding may contribute with a complementary hypothesis to the causes of dizziness among cochlear implant patients.

Adult↗
PubMed1995

Effect of dichotic presentation on the recognition of telegraphy signs.

The recognition of telegraphy signs (Morse code) masked by noise was studied at different interaural phase conditions at 250, 500, 1000 and 2000 Hz tone frequency in eight normal-hearing men. The possible effect of a left-right ear of dominance was considered. Best recognition was obtained at 500 Hz tone frequency with the telegraphy signs 180 degrees out of phase but with the noise in phase. When the telegraphy signs and noise were presented in one ear, recognition improved when the same masking noise without any phase difference was added to the other ear. The effect was most marked at 500 Hz. No significant difference was found between the left and right ear.

Adult↗
PubMed1995

Performance of electronic Morse decoders in decoding telegraphy masked by noise.

The performance of five different electronic Morse decoders in decoding telegraphy signs (Morse code) consisting of 800 Hz pure tones masked by a narrow-band noise with a bandwidth of 185 Hz (1/3 octave 713-890 Hz) centred at 800 Hz and a broadband noise (100-2,500 Hz) was studied at 20, 40, 80, 150 and 200 signs/min telegraphy speed. In steps of 1 dB the S/N ratios were varied from high values where 100% was recognized to low values where nothing was recognized. At narrow-band masking noise with 80 and 150 signs/min telegraphy speed a S/N ratio varying from +8 to +12 dB and +8 to +11 dB respectively was required for 100% recognition. At broad-band masking noise the S/N ratios required for 100% recognition varied from -4 to +3 dB at 80 signs/min telegraphy speed and -3 to +3 dB at 150 signs/min telegraphy speed. When compared to earlier findings in our laboratory concerning human recognition of Morse signs it seems that man outperforms electronic Morse decoders at low S/N ratios and low to moderate telegraphy speeds (< 100 signs/min).

Auditory Perception↗
PubMed1995

Recognition of telegraphy in hearing-impaired telegraph operators.

Recognition of Morse signs masked by noise was measured in five hearing-impaired telegraph operators with a high-frequency hearing loss. They all described problems typical for subjects with high-frequency hearing loss, i.e. problems with recognition of speech in noisy environments. Telegraphy speed, listening level, bandwidth of the masking-noise, frequency and interaural phase were systematically varied. At narrow-band masking with a bandwidth of 230 Hz (1/3 octave 891-1121 Hz) centred at 1000 Hz no statistical significant difference in recognition of telegraphy signs was found between the hearing-impaired subjects and the normal-hearing subjects investigated in our earlier studies at any telegraphy speed or at any S/N ratio. All hearing-impaired subjects improved in recognition when the telegraphy speed was lowered. When a broad-band noise (100-2500 Hz) was used as a masker all the hearing-impaired subjects improved in recognition when the frequency was lowered from 2000 to 500 Hz. At 40 signs/min telegraphy speed the hearing-impaired subjects showed a significantly lower recognition (p < 0.05) at low S/N ratios both at 2000 and 500 Hz frequency compared to the normal-hearing subjects investigated in our earlier studies. At monaural listening the normal-hearing subjects were significantly better (p < 0.01) in recognition. When the telegraphy signs were presented 180 degrees out of phase between the two ears, all subjects improved in recognition compared to when the telegraphy signs were presented in phase. This improvement was equal in hearing-impaired subjects and in the normal-hearing subjects investigated in our earlier studies.

Aged↗
PubMed1995

Postural control and vestibulospinal function in patients selected for cochlear implantation.

Postural control, vestibular and eye motor function were evaluated in seven postlingually deaf patients before cochlear implantation and were compared with 21 control subjects. Vibration to the calf muscles or galvanic electrical stimulation of the vestibular nerves, perturbed stance and body sway velocity, statistical variance of antero-posterior body sway and identification of characteristic parameters of postural dynamics were all evaluated. Vibration-induced body sway was increased among the patients compared with the normal subjects and there were differences in characteristic parameters of postural dynamics, indicating decreased postural control. Galvanic stimulation induced a body sway not significantly different from the control group suggesting that the patients selected for cochlear implantation, and with an otherwise reduced postural control, are sensitive to electrical stimulation of the vestibular nerve. Thus, postlingually deaf subjects who perceive a sensation of sound at electrical promontorial stimulation also respond with increased body sway to electrical stimulation aimed at the vestibular nerves. This finding may contribute an additional hypothesis to the causes of dizziness among cochlear implant patients, complementary to the that of wrongly placed electrodes and peroperative vestibular lesions.

Adult↗
PubMed1995

Pressure ulcers and wound healing: educating the spinal cord injured individual on the effects of cigarette smoking.

While it is well known that smoking causes an increased risk of lung cancer and cardiovascular problems, there is little information available about cigarette smoking and its adverse effects on pressure ulcers and wound healing in the individual with spinal cord injury (SCI). Due to SCI, circulation is already compromised. Smoking has a vasoconstrictive effect on the capillaries at the dermal level, which diminishes the amount of oxygenated blood reaching the tissues, further delaying the healing process of pressure ulcers and surgical wounds (Ting, 1991). A study was developed to focus on the knowledge of smoking among individuals with SCI. A video tape was prepared to provide comprehensive information about smoking. Twenty male patients with SCI were selected at random to view the videotape. A pre-test and post-test were given to evaluate the individual's knowledge of the effects of smoking on wound healing. The data collected demonstrated the effectiveness of the videotape as a teaching tool for increasing awareness of the adverse effects of cigarette smoking on pressure ulcer prevention and wound healing. Educating the individual with SCI on the effects of cigarette smoking is an important aspect of health education that needs to be addressed.

Adult↗
PubMed1995

Rotational ablation of discrete lesions in the coronary arteries is safe. A nonrandomized comparison with percutaneous transluminal coronary angioplasty.

Rotational ablation is receiving increasing attention as a new therapeutic intervention for coronary artery disease. In a nonrandomized study, we compared echocardiographic regional wall-motion scores of patients treated with rotational ablation with those of patients treated with percutaneous transluminal coronary angioplasty. We found that rotational ablation achieved angiographic results comparable to those of percutaneous transluminal coronary angioplasty, and was in fact associated with less myocardial ischemia. The reduction in ischemia observed in the ablation group might arise from shorter treatment times in those patients, from the use of nitroglycerin infusion in the ablation group, or from both factors.

Angioplasty, Balloon, Coronary↗
PubMed1994

A comparison of the efficacy and toxic effects of sustained- vs immediate-release niacin in hypercholesterolemic patients.

OBJECTIVE: To compare escalating doses of immediate-release (IR) and sustained-release (SR) niacin for effectiveness in reducing levels of low-density lipoprotein cholesterol and triglycerides and increasing levels of high-density lipoprotein cholesterol, and for the occurrence of adverse reactions, especially hepatotoxicity. DESIGN: Randomized, double-blind, parallel comparison of IR and SR niacin administered sequentially at 500, 1000, 1500, 2000, and 3000 mg/d, each for 6 weeks. SETTING: Cholesterol research center. PATIENTS: Forty-six adults, 23 in each group, with low-density lipoprotein cholesterol levels greater than 4.14 mmol/L (160 mg/dL) after 1 month of a step 1 National Cholesterol Education Program diet. OUTCOME MEASURES: Fourteen-hour fasting lipid and lipoprotein cholesterol levels, results of clinical laboratory tests, a symptom questionnaire, and withdrawal rates. RESULTS: The SR niacin lowered low-density lipoprotein cholesterol levels significantly more than IR niacin did at the dosage of 1500 mg/d and above, while IR niacin increased high-density lipoprotein cholesterol levels significantly more than SR niacin did at all dosage levels. The reduction in triglyceride levels was similar with IR and SR niacin. Nine (39%) of the 23 patients assigned to the IR dosage form withdrew before completing the 3000-mg daily dose; the most common reasons for withdrawal were vasodilatory symptoms, fatigue, and acanthosis nigricans. Eighteen (78%) of the 23 patients assigned to the SR dosage form withdrew before completing the 3000-mg daily dose; the most common reasons for withdrawal were gastrointestinal tract symptoms, fatigue, and increases in levels of liver aminotransferases, often with symptoms of hepatic dysfunction. None of the patients taking IR niacin developed hepatotoxic effects, while 12 (52%) of the 23 patients taking SR niacin did. CONCLUSION: The SR form of niacin is hepatotoxic and should be restricted from use. The IR niacin is preferred for the management of hypercholesterolemia but can also cause significant adverse effects and should be given only to patients who can be carefully monitored by experienced health professionals.

Adult↗