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Biomedical subjects

S Morris

Publications and source records attributed to S Morris.

At least 199 records · Page 11Linked to original sources
PubMed1991

Chemical and electrochemical reduction rates of cyclic nitroxides (nitroxyls).

The reduction rates of five-membered pyrrolidine and pyrroline, and six-membered piperidine nitroxides (alternatively termed nitroxyls) containing various substituents were determined under homogeneous conditions using ascorbate, and electrochemically under heterogeneous conditions. The results were compared with data from the literature. It was shown that the increased rates of reduction of six-membered nitroxides, compared with those of the five-membered nitroxides, cannot be explained on the basis of differences in electrochemical potentials but, rather, can be ascribed to differences in the accessibility of the nitroxide group. A double bond in the five-membered nitroxyls increases the reduction rate. Within any ring system, the reduction rates of nitroxides using ascorbate can be correlated with the inductive substituent constants. The half-way potentials for electrochemical reduction within a series of nitroxides based on the same ring correlate with logarithms of the rates using ascorbate and with the inductive constants. The potentials for one-electron oxidation of the nitroxides were related to the inductive constants.

Ascorbic Acid↗
PubMed1991

Prevention of selenite cataract by vitamin C.

Studies have been conducted to determine the efficacy of vitamin C in the prevention of cataracts induced by selenite. Administration of the latter to rat pups results in the development of advanced cataracts within 5 days. Treatment with ascorbate had a significant preventive effect. The observations indicate that selenite cataract is due to an oxidative stress to the lens. In addition, the findings are in conformity with our view that ascorbate functions as an anticataractogenic substance.

3,4-Methylenedioxyamphetamine↗
PubMed1991

A survey of nosocomial respiratory viral infections in a children's hospital: occult respiratory infection in patients admitted during an epidemic season.

OBJECTIVE: To define the extent of shedding of respiratory viruses and Mycoplasma pneumoniae among a population of pediatric patients admitted to the hospital during a winter epidemic period and to identify nosocomial infections within this population. DESIGN: An open, prospective survey of patients admitted to three wards (General Medical, Respiratory Infectious, and Infectious Diseases) of a pediatric hospital during a defined three-month period. PATIENTS: All patients with medical, respiratory, and infectious conditions admitted to three wards of the Adelaide Children's Hospital had nasopharyngeal aspirations performed at the time of admission with the purpose of documenting viral and M pneumoniae shedding. Patients were monitored daily for the development of symptoms of respiratory infection or new symptoms of respiratory disease. Such patients underwent a further nasopharyngeal aspiration for the purpose of diagnosing hospital-acquired infection. RESULTS: Nasopharyngeal aspirations were obtained from 601 patients. Forty-seven percent of asymptomatic patients were positive for a respiratory virus or M pneumoniae, and 61% of patients with respiratory symptoms were also positive. Gastroenteritis patients shed viruses in 66% of cases. Respiratory symptoms were initially overlooked by admitting physicians but subsequently identified in 110 cases, and 46% of these were found to be positive for a respiratory virus or M pneumoniae. There were 18 possible hospital acquired infections among the 293 initially virus-negative patients. Multiple isolates were obtained from a substantial number of patients, especially those with respiratory symptoms. CONCLUSIONS: A substantial proportion of all patients admitted to a pediatric hospital during winter represent a potential source of infection, and strict infection control measures should be enacted to limit the spread of these infections.

Australia↗
PubMed1991

The rectus femoris myocutaneous flap for closure of difficult wounds of the abdomen, groin, and trochanteric areas.

The rectus femoris myocutaneous flap has proved to be an effective means of closing particularly difficult wounds in 2 patients. One patients had a massive defect in the lower abdomen, pubic, and right groin area after the radical resection of a recurrent pleomorphic liposarcoma of the spermatic cord. The second patient presented with a huge, right greater trochanteric wound measuring 15 cm in diameter. Both patients progressed to relatively uneventful primary healing.

Adult↗
PubMed1990

Surgical augmentation of skin blood flow and viability in a pig musculocutaneous flap model.

A porcine rectus abdominis musculocutaneous (TRAM) flap model was designed and validated in nine pigs. This TRAM flap was based on the deep inferior epigastric (DIE) vessels with an 8 x 18 cm transverse skin paddle at the superior end of the rectus abdominis muscle. The model was subsequently used to test our hypothesis of surgical augmentation of flap viability by vascular territory expansion. Specifically, we observed that ligation of the superior epigastric (SE) vessels at 4, 7, 14, and 28 days (N = 6 to 8) prior to raising the TRAM flaps significantly increased (p less than 0.05) the length and area of the viable skin in the transverse skin paddles of the treatment flaps compared with the contralateral shammanipulated control flaps. This significant increase in skin viability was seen to be accompanied by a significant increase (p less than 0.05) in skin and muscle capillary blood flow in the treatment TRAM flaps compared with the controls (N = 9). The mechanism of vascular territory expansion is unclear. We postulate that hypoxia resulting from the ligation of the superior epigastric vessels prior to the flap surgery may play a role in the triggering of the deep inferior epigastric artery to take over some of the territory previously perfused by the superior epigastric artery. This would then increase the skin and muscle capillary blood flow in the transverse paddle when the TRAM flap was raised on the deep inferior epigastric vascular pedicle.

Animals↗
PubMed1990

The effects of menthol on reaction time and nasal sensation of airflow in subjects suffering from the common cold.

The effects of sucking a lozenge containing 11 mg L-menthol on reaction time and nasal sensation were investigated in a double blind trial on 60 subjects suffering from the common cold. Reaction time was determined by measuring the response time to a stimulus presented on a microcomputer screen and nasal sensation was scored on a visual analogue scale. Menthol ingestion compared to placebo caused a significant increase in nasal sensation of airflow which persisted for up to 30 min. The simple and choice reaction times measured before ingestion of the lozenge were similar to those found in healthy uninfected subjects and there was no change in reaction time after ingestion of menthol.

Adolescent↗
PubMed1990

The effects of oral administration of (-)-menthol on nasal resistance to airflow and nasal sensation of airflow in subjects suffering from nasal congestion associated with the common cold.

The effects of oral administration of a lozenge containing 11 mg (-)-menthol on nasal resistance to airflow (NAR) and nasal sensation of airflow in 62 subjects suffering from nasal congestion associated with naturally acquired common cold infection have been studied. NAR was measured by posterior rhinomanometry and nasal sensation of airflow by means of a visual analogue scale (VAS). The effects of the lozenge were compared with a candy placebo lozenge in a double blind randomized trial. NAR showed a significant increase (P less than 0.05) in both the menthol and placebo groups over the 2 h experiment with no difference between the groups at any time. The VAS scores showed significant changes of subjective improvement in nasal sensation of airflow (P less than 0.001) in the menthol-treated group 10 min after dosing whereas the placebo group showed no change. It is concluded that dosing with 11 mg menthol in subjects with common cold has no effect on NAR as measured by posterior rhinomanometry but causes a marked change in nasal sensation of airflow with a subjective sensation of nasal decongestion.

Administration, Oral↗
PubMed1990

Effects of the antiprogesterone RU486 in the early follicular phase of the menstrual cycle.

To investigate the role of progesterone (P) in the early follicular phase, the antiprogesterone effect of RU486 was examined in five normally cycling women monitored by daily hormonal levels during three consecutive cycles (control, treatment, and recovery). In addition, luteinizing hormone (LH) pulse characteristics were assessed by frequent blood sampling (10 minutes for 10 hours) on day 3 of the control and the corresponding day of treatment cycles. Administration of RU486 (3 mg/kg, orally) for the first 3 days of the menstrual cycle did not significantly alter the length of the follicular phase (13.4 +/- 1.7 to 15.2 +/- 1.3 days), the LH surge, or the luteal phase length (12.2 +/- 0.5 to 12.6 +/- 0.7 days). The intermenstrual length of the treatment cycle (29.8 +/- 1.9 days) did not differ from the control (27.6 +/- 1.8 days) or recovery cycles (29.6 +/- 2.5 days). Integrated secretion of P and estradiol (E2) did not vary during the luteal phase of the control, treatment, or recovery cycles. During RU486 treatment, LH pulse frequency, pulse amplitude, and mean LH were not altered. Whereas mean E2 levels were significantly decreased from 150.5 +/- 15.1 to 110.1 +/- 7.0 pmol/L, follicle-stimulating hormone, P, adrenocorticotropin hormone, and cortisol were not significantly altered. Thus, in spite of the transient decrement in E2 secretion during RU486 treatment, the integrity of the ovulatory menstrual cycle was maintained. We conclude that administration of the antiprogesterone RU486 at the dose used during the first 3 days of the follicular phase does not perturb menstrual cyclicity.

Adrenocorticotropic Hormone↗
PubMed1989

Phase I trial of combined therapy with bleomycin and the calmodulin antagonist, trifluoperazine.

Calmodulin antagonists, such as trifluoperazine, can enhance the cytotoxic effects of bleomycin both in tissue culture and in vivo. Therefore, we evaluated the effects of combination treatment with these drugs in a phase I clinical trial. Patients with objectively measurable or evaluable cancer refractory to conventional treatment who had an acceptable performance status (ECOG 0-2) and acceptable laboratory studies were eligible. All patients gave written informed consent. A cycle of therapy consisted of three weekly treatments with trifluoperazine (days 1-4) and 30 IU bleomycin (day 3). After three patients completed a cycle of therapy without experiencing dose-limiting toxicity, new patients were entered in the study and received a higher dose of trifluoperazine. The dose of bleomycin remained constant. Evaluable patients received at least 2 weeks of treatment and survived for 6 weeks; of 19 patients, 2 were unevaluable. The major toxicities were neurological and pulmonary and included one case of fatal pneumonia with interstitial pulmonary fibrosis. There was no hematologic toxicity. Two patients underwent partial responses (PRs) and two had complete responses (CRs). We conclude that trifluoperazine can safely be given with bleomycin and that further study of the potential efficacy of this treatment is indicated.

Adult↗
PubMed1989

Intracellular metallothionein concentration and the rate of zinc or cadmium influx and MT mRNA accumulation in a CHO Cdr variant.

The regulation of metallothionein (MT) gene expression in a cadmium resistant CHO cell line which overproduces MT was examined in this study. Our results show that MT mRNA levels reach a maximum 24-30 h after a primary zinc exposure and, subsequently, MT mRNA concentrations decline. This decrease in MT mRNA levels can be correlated with the accumulation of metallothionein and decreased rates of zinc and cadmium uptake.

Animals↗
PubMed1989

Prospective study of nosocomial rotavirus infection in a paediatric hospital.

Hospital-acquired enteric infections, particularly those due to rotavirus, were investigated by studying 220 patients under 3 years of age who were admitted without gastroenteritis to two paediatric general medical wards during a 10 month period. Faecal specimens were collected within 48 h of admission and then daily until the patients were discharged. Samples were also collected after discharge if patients developed enteric symptoms within 2 days of discharge. Fourteen per cent (31 of 220) of patients acquired rotavirus infections while in hospital, 23% (seven of 30) excreted rotavirus only after discharge; 29% of patients infected with rotavirus were asymptomatic (nine of 31). Acquisition of rotavirus infection was most prevalent during the months May-August, with a prevalence of 34% (12 of 35) in May. Hospitalization was prolonged in those patients who acquired rotavirus (11.1 days compared with 8.0 days, P less than 0.05). This study highlights the importance of rotavirus as a cause of hospital cross-infection, particularly in the very young patient, and emphasizes the need for further assessment of factors involved in its acquisition. In order to determine correctly the incidence of hospital-acquired illness, it is essential to follow patients after discharge from hospital. This study reinforces the importance of developing preventive measures in order to reduce the frequency of this illness.

Australia↗
PubMed1988

Recurrent seizures in childhood. Western Cape profile.

In over 50% of children with recurrent seizures in a South African hospital population the onset of attacks was before the age of 2 years. In 32% of patients there was a history of perinatal complications and 11% had a history of meningitis; 38% of the children had abnormalities on physical examination and 55% were intellectually handicapped. Acceptable seizure control was achieved in 71% of patients and 68% were treated with a single anticonvulsant. Appropriate educational placement had not been achieved for 22%. It is concluded that a reduction in the incidence of epilepsy in the community can be achieved by improvements in obstetric/neonatal services and by the raising of living standards. The abolition of racial segregation at special schools and training centres will alleviate the present shortage of places for children with epilepsy who cannot cope at regular schools.

Adolescent↗
PubMed1988

Age-dependent variation for inducibility of metallothionein genes in mouse liver by cadmium.

Cadmium is a toxic metal that induces the expression of metallothionein genes in many tissues and that binds avidly to metallothionein, a soluble transition metal binding protein. The present study examined the temporal pattern and magnitude of accumulation of metallothionein mRNA in liver of C57BL/6J mice of various ages treated with cadmium. In adult female mice, accumulation was dependent on the dosage level of cadmium and related to the concentration of this metal in liver. The accumulation of metallothionein mRNA in liver depended on age at exposure to cadmium. Intraperitoneal administration of 2 mg of cadmium per kg provoked small increases (two- to threefold) in levels of metallothionein mRNA in livers of 7- and 14-day-old mice. In contrast, cadmium treatment of 28- and 56-day-old mice resulted in 12- to 19-fold increases in levels of metallothionein mRNA in liver with maximum increases occurring 3 to 4 hr after treatment. Because similar patterns for the accumulation of cadmium of liver were found in 7-, 28-, and 56-day-old mice, observed age-dependent differences in induction of metallothionein mRNA in liver were probably not due to differences in the accumulation of cadmium in this organ. Taken together, these data suggest that tissue-specific factors controlling the expression of metallothionein genes may account for developmental variation in the inducibility of these genes by cadmium. Ontogenic variation in accumulation of metallothionein mRNA after cadmium treatment may be a factor in developmental variation in the acute lethality of cadmium in C57BL/6J mice.

Age Factors↗