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Biomedical subjects

N Peters

Publications and source records attributed to N Peters.

At least 19 recordsLinked to original sources
PubMed1992

Diagnosis and management of giant intrasacral schwannoma.

Giant intrasacral schwannoma is a rare cause of a retrorectal mass in an adult patient. Only 21 such tumors have been reported. The diagnosis of this intraosseous nerve sheath tumor is heralded by its minimal symptoms in relation to its often striking radiographic findings and is verified by its unique morphology. Surgical resection is complex because of its anatomic location and propensity for local recurrence. The need for adequate tumor removal must be balanced against the preservation of nerve function. The presentation, diagnosis, and management of intrasacral schwannomas are reviewed, as exemplified in this case presentation and literature review.

Adolescent↗
PubMed1992

Chemodectoma of the head and neck: results of treatment in 84 patients.

Eighty-four patients with chemodectoma of the head and neck presented to the Royal Marsden Hospital between 1949 and 1985. For tumors arising at the skull base (glomus jugulare and glomus tympanicum) 46 were treated with radiotherapy alone resulting in an actuarial local control rate of 73% at 25 years; 13 were treated with surgery plus radiotherapy with no recurrences during a median follow-up of 9 years; 4 had surgery alone but all recurred by 7 years. For tumors of the soft tissues of the neck (carotid body and glomus vagale) 13 were treated with surgery alone with an actuarial control rate of 54% at 15 years; 4 were treated with radiotherapy which resulted in local control at 1, 2, 8 and 11 years; and one patient who received both surgery and radiotherapy remained controlled at 1 year. Although comparison between radiotherapy and surgery in terms of tumor control is not simple, the case is argued for more frequent use of radiotherapy at all sites. This case is strengthened by minimal morbidity from radiotherapy in doses which appear effective: in the range of 45-50 Gy in 25 daily fractions over 5 weeks.

Adult↗
PubMed1991

Biological significance of cell cycle kinetics in 128 standard risk newly diagnosed patients with acute myelocytic leukemia.

Bromodeoxyuridine (BrdU) was administered to 128 newly diagnosed patients with standard risk acute myelocytic leukaemia (AML) for cell cycle measurements. Labelling indices (LI) were obtained from both the bone marrow aspirate (BMasp) and biopsies (bx) and durations of S-phase (Ts) and total cell cycle time (Tc) were measured by double-labelling the S-phase cells in vitro with tritiated thymidine. Median LI BMasp was 8% and from BMbx was 25%. The median Ts was 12 h (range 3.1-35 h) and Tc was 48 h (range 11.5-211 h). All patients received induction therapy with a combination of cytosine arabinoside and an anthracycline. Outcome of therapy or FAB type were not related to cell cycle characteristics. Patients with above median LI BMasp, however, had longer remission durations (P = 0.03) as did patients with above median Ts (P = 0.03) and Tc (P = 0.03). Upon longer follow-ups, even some of the patients with slowly cycling myeloblasts have relapsed (log rank P = 0.453 and 0.203 for Ts and Tc respectively). We conclude that patients with rapidly cycling cells tend to relapse faster; however, slowly cycling nature of myeloblasts is not associated with curability.

Adult↗
PubMed1990

Elderly male spouses as caregivers--toward an understanding of their experience.

Male caregivers have difficulty assuming personal and household responsibilities; they seem to cope by focusing on the caregiving tasks and projects, establishing daily routines, and carving out their own territory in the home. To facilitate effective interventions, nurses should ascertain the elderly male spouse's meaning of caregiving. This would enable practitioners to foster the caregiver's strengths and provide support in those areas where burden or difficulties are experienced. Husbands as caregivers were more likely than wives to seek the help of formal providers and receive more informal support. Male caregivers tend to not participate in support groups. Before making a referal, nurses should ensure the group is geared to the special needs of the man.

Aged↗
PubMed1989

Anxiety, type A personality and endocrine responses to surgery.

Twenty-seven patients underwent major abdominal surgery. Trait Anxiety and Type A personality were measured pre-operatively, and plasma cortisol, adrenaline and noradrenaline were measured pre-, per- and post-operatively. Anxiety correlated positively with noradrenaline but negatively with cortisol and adrenaline. Type A also showed opposite correlations with adrenaline and noradrenaline.

Adolescent↗
PubMed1988

The relationship of preoperative distress to endocrine and subjective responses to surgery: support for Janis' theory.

To test Janis' theory that preoperative worry can improve postoperative recovery, endocrine and subjective responses were measured in 27 patients undergoing major abdominal surgery which entailed threat to their health or longevity. Questionnaires to assess emotional and somatic state were completed preoperatively and for 7 days postoperatively. Plasma cortisol, noradrenaline, adrenaline, and glucose were measured pre-, per-, and postoperatively. Preoperatively, noradrenaline correlated positively with pain and distress, and adrenaline negatively. Postoperatively, endocrine levels and distress were not clearly related. Nevertheless, preoperative pain negatively correlated with postoperative adrenaline and cortisol levels. This, and the negative correlation between preoperative distress and postoperative pain are consistent with Janis' theory. In addition, we found that the longer patients waited on the day of surgery, the greater were the cortisol, noradrenaline, and glucose responses.

Adolescent↗
PubMed1987

Expression of the precore region of an avian hepatitis B virus is not required for viral replication.

The core-antigen-coding region of all hepadnaviruses is preceded by a short, in-phase open reading frame termed precore whose expression can give rise to core-antigen-related polypeptides. To explore the functional significance of precore expression in vivo, we introduced a frameshift mutation into this region of the duck hepatitis B virus (DHBV) genome and examined the phenotype of this mutant DNA by intrahepatic inoculation into newborn ducklings. Animals receiving mutant DNA developed DHBV infection, as judged by the presence in hepatocytes of characteristic viral replicative intermediates; molecular cloning and DNA sequencing confirmed that the original mutation was present in the progeny genomes. Infection could be efficiently transmitted to susceptible ducklings by percutaneous inoculation with serum from mutant-infected animals, indicating that infectious progeny virus was generated. These findings indicate that expression of the precore region of DHBV is not essential for genomic replication, core particle morphogenesis, or intrahepatic viral spread.

Animals↗
PubMed1985

Ventricular arrhythmias complicating weight reduction therapy in a patient with a prolonged QT interval.

Serious ventricular arrhythmias are known to occur in patients with long QT intervals. We describe a case of torsade de pointes occurring in a patient with a prolonged QT interval while taking a 1000 calorie diet, diethylpropion hydrochloride (Tenuate Dospan) and bendrofluazide. In patients with long QT intervals, hypokalaemia and drugs which further delay repolarization may facilitate the development of life threatening arrhythmias.

Adult↗
PubMed1983

Peripheral glucose uptake in young men with myocardial infarction.

Forearm glucose uptake (FGU) was studied during 100 g oral glucose tolerance tests (GTT) in nonobese, nondiabetic men who had suffered a myocardial infarction (MI) at or before the age of 40, and the results compared with the response in age-matched normal men. In the MI group the rise in both glucose and insulin concentrations after glucose loading was similar to that in normal subjects, although in the former, peak levels tended to be slightly higher. Concomitant FGU, however, was significantly greater in the MI group than in control subjects in the period 0-90 min and in the test as a whole (0-180 min). The results show that at least in some nondiabetics suffering MI at an early age hyperinsulinism is not a feature and peripheral tissue sensitivity is increased.

Adult↗
PubMed1978

Temperature-dependent growth and regression of epidermal tumors in the european eel (Anguilla anguilla L.).

The population of eels in the Elbe estuary showed a high rate of affliction with epidermal papillomas. Distinct seasonal fluctuations were observed in the frequency of occurrence and tumor size. In spring and autumn, the frequency was low, and the tumors were relatively small. In summer, the tumors reached a maximum in both frequency and size. A distinct influence of water temperature on tumor growth was demonstrated experimentally. Summer temperatures of 15--22 degrees C caused very rapid growth. In the field and in the laboratory, the tumors exhibited a fourfold increase in average volume within 3 months. These fast-growing neoplasms had certain relatively uniform histologic features. The tumor cells were separated by wide intercellular spaces. The basal layer was composed of tall columnar cells, while the surface layer was composed of slightly flattened cells. Winter water temperatures (5--10 degrees C) inhibited tumor growth and even caused tumor regression. In 3 months, the papillomas shrank to half of their initial size. Histologic and ultrastructural examinations revealed signs of tissue degeneration: necrobiotic processes in the epidermal region, cellular and nuclear polymorphisms, dissolution of membranes, loss of cell integrity, and loosening and reduction in size of the basal cell layer.

Anguilla↗
PubMed1977

Geographic variations in tumor prevalence among marine fish populations.

A global epidemiological study on the frequency of skin papillomas among various flatfish species (Pleuronectids), papillomas of eels and the virus induced lymphocystis disease has revealed particular distribution patterns. Skin papillomas are prevalent among at least 20 flatfish species of the northern Pacific Ocean, Bering Sea, Sea of Okhotsk, and Japan Sea but appear to be absent from the Atlantic, North Sea, and the Caribbean Sea. The opposite is found for lymphocystis, which is common among flatfish species of the Atlantic shores of Europe and North America. Similarly the skin papillomas of eels are restricted to relatively small region along the European coast extending from the Baltic countries to Denmark, Germany and Holland. Superimposed on this global distribution pattern are local variations in tumor prevalences which can vary from about 58% to 0.01%. The geographic distribution pattern points to the existence of areas around the globe in which flatfish or eels are able to develop skin papillomas. Outside these areas of "potential skin papilloma risk," flatfish and eel populations are not afflicted with papillomas even if they inhabit estuaries or rivers with a high man-made or naturally-occurring pollution.

Animals↗
PubMed1976

Neurosurgical microvascular bypass for stroke.

A review of the present status of neurosurgical vascular bypass for problems of cerebrovascular occlusive disease is presented. In 70 patients who have undergone operations by one surgical team, the results are most encouraging in cases of transient ischemic attacks with hemodynamic lesions previously considered inoperable or inaccessible in the cerebral vasculature. The morbidity rate is acceptable and the present operative mortality rate is 1.4 percent.

Aged↗