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Biomedical subjects

J Nelson

Publications and source records attributed to J Nelson.

At least 199 records · Page 11Linked to original sources
PubMed1992

Grading nephroureteral dilatation detected in the first year of life: correlation with obstruction.

To understand better the significance of pediatric idiopathic nephroureteral dilatation the renal ultrasound images of patients less than 1 year old with hydronephrosis or hydroureteronephrosis were graded and compared to the radiological diagnosis of obstruction as determined by diuresis renography and/or urography. The study included 73 boys and 30 girls with hydronephrosis (76 patients) or hydroureteronephrosis (27). For hydronephrosis obstruction was diagnosed in 56 children (74%) and involved 61 of 97 kidneys (63%). For obstructed kidneys the mean grade of hydronephrosis (3.4 +/- 0.7 standard deviation) was statistically different from that of nonobstructed kidneys (1.6 +/- 0.8 standard deviation) (p less than 0.05). When the value to predict obstruction was set at grade 3 hydronephrosis or greater there was an 88% sensitivity and 95% specificity. For hydroureteronephrosis obstruction was diagnosed in 15 of 27 children (56%) and involved 17 of 34 kidneys (50%). The degree of dilatation was weighted as a score to assess the grades of hydronephrosis and ureteral dilatation, namely hydroureteronephrosis score equals grade of hydronephrosis plus grade of ureteral dilatation. In obstructed megaureters the mean hydroureteronephrosis score (5.8 +/- 1.0) was statistically different from that for nonobstructed megaureters (mean hydroureteronephrosis score 2.7 +/- 1.9) (p less than 0.001). When the value to predict obstruction was set at hydroureteronephrosis score of 5 or greater there was a 94% sensitivity and 80% specificity. Although ultrasound examination alone cannot be used to diagnose urinary obstruction, the radiological diagnosis of obstruction is linked with the grade of hydronephrosis or score of hydroureteronephrosis.

Age Factors↗
PubMed1992

Report of the Conference on Low Blood Cholesterol: Mortality Associations.

BACKGROUND: A National Heart, Lung, and Blood Institute (NHLBI) Conference was held October 9-10, 1990, to review and discuss existing data on U-shaped relations found between mortality rates and blood total cholesterol levels (TC) in some but not other studies. Presentations were given from 19 cohort studies from the United States, Europe, Israel, and Japan. A representative of each study presented its findings and also submitted tables of proportional hazards regression coefficients for entry TC levels in regard to death, and these were incorporated into a formal statistical overview adjusted for age, diastolic blood pressure, cigarette smoking, body mass index, and alcohol intake, as available. METHODS AND RESULTS: The U-shape for total mortality in men and the flat relation in women resulted largely from a positive relation of TC with coronary heart disease death and an inverse relation with deaths caused by some cancers (e.g., lung but not colon), respiratory disease, digestive disease, trauma, and residual deaths. Risk for combined noncardiovascular, noncancer causes of death decreased steadily across the range of TC. The conference considered possible explanations for the statistical associations found between low TC levels or active TC lowering and certain causes of death. One is that TC is lowered by some disease conditions themselves, such as wasting in chronic pulmonary disease or reduced production and secretion of cholesterol-bearing lipoproteins with liver disease. In this sort of situation, the TC:mortality association found in observational studies may be due to preexisting disease. This was addressed by excluding early deaths from the analysis, which did not change the results. The conference considered as well the biological function of cholesterol, which, if seriously deranged, might hypothetically cause a wide variety of diseases and dysfunction. The conference also considered the biological functions that might provide plausible mechanisms for the associations found. CONCLUSIONS: Definitive interpretation of the associations observed was not possible, although most participants considered it likely that many of the statistical associations of low or lowered TC level are explainable by confounding in one form or another. The conference focused on the apparent existence and nature of these associations and on the need to understand their source rather than on any pertinence of the findings for public health policy. Further research is recommended to explain the observed associations of low TC levels (and TC lowering) with certain noncardiovascular diseases. This includes studies of the time course of TC change in disease, the relation of TC to morbidity, further studies of possible epidemiological confounding, monitoring of population trends in TC and mortality, further studies of the relations in women, auditing of noncardiovascular events in trials, studies of cell membrane, genetic and molecular links to cholesterol metabolism, TC level and disease, studies of disease manifestations in specific lipid disorders, and further study of the proposed causal mechanisms linking low TC and hemorrhagic stroke.

Alcohol Drinking↗
PubMed1992

Simple surgical treatment of nonparasitic hepatic cysts.

Benign nonparasitic liver cysts are uncommon lesions. Incidental diagnosis is increasing with the advent of routine abdominal computed tomography and ultrasound scanning. Cysts that attain massive proportions often become symptomatic and require therapeutic intervention. Surgical resection and Roux-en-Y cystojejunostomy drainage have been the treatments of choice, but simpler unroofing techniques without drainage have recently been employed with success. Three patients with symptomatic, large, nonparasitic cysts were surgically treated in such a fashion without complication and form the basis of this report. The technique of wide unroofing involves excision of the nonhepatic cyst wall with oversewing of communicating biliary radicals. No recurrences have been detected in follow-up screening. Wide unroofing is a simple and yet reliable surgical option for the treatment of symptomatic hepatic cysts.

Aged↗
PubMed1992

[Mechanism of the effect of serine and threonine on ammoniagenesis and biosynthesis of orotate in the mouse].

We have evaluated the effects of serine and threonine on orotate metabolism in mice, by injecting i.p. 0.5 to 1.5 mmol/100 g of body weight, during 4 weeks of experimentation. The results indicate that serine as well as threonine cause a significant increase (p less than 0.01) of plasma ammonia and urinary orotate. We have also studied the effects of various inhibitors, adenine (0.3% diet), N-(phosphonoacetyl)-L-aspartate (PALA) (10 mg/100 g, i.p.), acivicin (1 mg/100 g, i.p.) and cycloheximide (1.5 mg/kg, i.p.) on orotate synthesis in mice injected with serine (2.5 mmol/100 g, i.p.) or threonine (1.25 mmol/100 g, i.p.). The results show an increase (p less than 0.05) of urinary orotate following an adenine-rich diet, and a reduction of orotate following PALA (p less than 0.01). The orotic aciduria remained insensitive to acivicin while it was inhibited by cycloheximide. These results suggest that adenine blocks the utilisation of orotate and consequently could affect the biosynthesis of pyrimidines; the induction of orotate by serine and threonine is controlled by the translation of a specific protein synthesis, and necessarily implicates the mitochondrial carbamyl phosphate synthetase-I (CPS-I). The regulating step in this synthesis of orotate could also be the transport of carbamyl-phosphate from the mitochondria to cytosol.

Adenine↗
PubMed1991

Relationships between energy level and insulin secretion in isolated rat islets of Langerhans. A study at various pH values.

To define better the role of [ATP]/[ADP] in insulin release from pancreatic islets, changes in the adenine nucleotide ratios elicited by alterations in external pH were correlated with the secretion profiles produced by administration of two metabolic secretagogues, 16 mM glucose and 10 mM alpha-ketoisocaproic acid. Experiments were carried out in buffers with and without bicarbonate, in the pH range 6.5-7.7. Insulin release was dependent on pHe irrespective of the secretagogue used. Secretion profiles for alpha-ketoisocaproic acid were the same both with and without bicarbonate; the release was decreased below pH 7.1 but maintained at 7.4-7.7. The same pattern was seen with glucose in media buffered with Hepes. With bicarbonate present, secretion caused by high glucose showed a bell-shaped dependence on [H+], with reductions at the acid and alkaline sides of pH 7.1-7.4. [ATP] and [ADP] were higher when Hepes was the buffer, at all pH values studied. The [ATP]/[ADP] declined with increasing pH under both basal and stimulated conditions; the values were always larger after stimulation although at pH 7.7 with bicarbonate present and glucose as the stimulant the difference was very small. It is concluded that: (i) the [ATP]/[ADP] in pancreatic islets is markedly dependent on pHe; (ii) there is no straight-forward correlation between either [ATP] or the absolute value for [ATP]/[ADP] and insulin secretion; and (iii) a rise in [ATP]/[ADP] is necessary for glucose-stimulated insulin release although it is not always the rate-determining event.

Adenosine Diphosphate↗
PubMed1991

Neurogenesis in the brain auditory pathway of a marsupial, the northern native cat (Dasyurus hallucatus).

Neurogenesis in the auditory pathway of the marsupial Dasyurus hallucatus was studied. Intraperitoneal injections of tritiated thymidine (20-40 microCi) were made into pouch-young varying from 1 to 56 days pouch-life. Animals were killed as adults and brain sections were prepared for autoradiography and counterstained with a Nissl stain. Neurons in the ventral cochlear nucleus were generated prior to 3 days pouch-life, in the superior olive at 5-7 days, and in the dorsal cochlear nucleus over a prolonged period. Inferior collicular neurogenesis lagged behind that in the medial geniculate, the latter taking place between days 3 and 9 and the former between days 7 and 22. Neurogenesis began in the auditory cortex on day 9 and was completed by about day 42. Thus neurogenesis was complete in the medullary auditory nuclei before that in the midbrain commenced, and in the medial geniculate before that in the auditory cortex commenced. The time course of neurogenesis in the auditory pathway of the native cat was very similar to that in another marsupial, the brushtail possum. For both, neurogenesis occurred earlier than in eutherian mammals of a similar size but was more protracted.

Aging↗
PubMed1991

The effect of bicarbonate on resuscitation from cardiac arrest.

STUDY OBJECTIVES: This study attempted to determine the effect of bicarbonate administration on resuscitation in a porcine model of prolonged cardiac arrest. DESIGN: After instrumentation, 26 swine were subjected to ventricular fibrillation for 15 minutes (16 animals) or 20 minutes (ten animals) with no resuscitative efforts. INTERVENTIONS: Resuscitation attempts with open-chest cardiac massage and epinephrine were used in all animals after the arrest period. The experimental group was given sodium bicarbonate (3 mEq/kg), and the control group received 3% saline (5 mL/kg) at the initiation of cardiac massage. MEASUREMENTS: Resuscitation success, hemodynamics, and arterial and mixed venous gases were compared in the bicarbonate and hypertonic saline-treated groups. RESULTS: There was no difference in resuscitation rates between bicarbonate and nonbicarbonate-treated swine. After 15 minutes of ventricular fibrillation, six of eight bicarbonate-treated swine were resuscitated successfully compared with five of eight hypertonic saline-treated animals. None of the five bicarbonate-treated or five hypertonic saline-treated swine that underwent 20 minutes of ventricular fibrillation were resuscitated. The arterial and mixed venous pH values were significantly different in the bicarbonate-treated animals from values in the control group. There was no difference in systolic or diastolic blood pressures or myocardial perfusion pressure between the bicarbonate and hypertonic saline-treated animals. CONCLUSION: Despite correlation of arterial and venous acidemia, the use of sodium bicarbonate did not improve resuscitation from prolonged cardiac arrest.

Animals↗
PubMed1991

Plasma renin activity in renal transplant patients with hypertension.

Chronic renal allograft rejection (CR) is the major cause of graft loss after 1 year following transplantation. Hypertension (HTN) and proteinuria (Up) are the hallmarks of this immunologic allograft response. Over 1 year, 23 patients posttransplantation and with HTN (diastolic greater than 95 mm Hg) were examined. Serial serum creatinine (Scr), Up, urine creatinine (Ucr), and resting and enalapril challenged (EC) plasma renin activity (PRA) were all determined. Renal artery stenosis was excluded by noninvasive imaging. Of the 23 patients, eight eventually lost their renal allografts, while 15 maintained satisfactory renal function (Scr less than 2.5). Results of this study show that: 1) worsening renal function (RF) increases EC reactivity; 2) the presence of proteinuria is not itself related to increase in EC activity; 3) renin before and after EC was higher (P = .06) in the allograft loss group. In this study, patients with high PRA represent the highest EC responses. Therefore, they display not macrovascular lesions, but microvascular intrarenal disease; this defect is most likely secondary to chronic immunologic insult.

Adult↗
PubMed1991

Synthetic murine epidermal growth factor sequence 20-31 is mitogenic and angiogenic.

Epidermal growth factor (EGF) and its homologue, transforming growth factor alpha (TGF alpha), are mitogenic, angiogenic and tumour-promoting polypeptides. Much effort has therefore been directed towards the development of EGF/TGF alpha antagonists as a potential cancer therapy. Initial reports that some EGF/TGF alpha synthetic fragments possess EGF-receptor binding activity have not been confirmed in subsequent studies. We have found, however, that the murine EGF B-loop sequence: Ac-[(S-acetamidomethyl)-Cys20,31]-EGF-(20-31)-NH2 [(mEGF-(20-31)] produces biological effects consistent with the parent molecule in bovine, murine, chick and human, but not rat, model systems. In parallel experiments, both mEGF and mEGF-(20-31) elicit migratory, cytoprotective, growth-stimulatory, growth-inhibitory and angiogenic responses. The reverse B-loop sequence, mEGF-(31-20), is also mitogenic and angiogenic. The C-loop sequence, mEGF-(33-42), has no mitogenic or angiogenic activity when applied alone, does not block the mitogenic effect of mEGF, but does block the angiogenic effect of mEGF. It has not been established that the EGF receptor is the target for these fragments, but the results suggest that the residual biological activities of EGF fragments merit further investigation.

3T3 Cells↗
PubMed1991

Clinical evaluation of a new chest tube used in neonates.

We report preliminary experience with a newly designed chest tube (JCT), for evacuation of neonatal pneumothorax. The catheter has a unique pigtail confirguration at the distal end, intended to simplify placement and minimize chest wall and lung trauma by reduced tube size and depth and insertion. Thirty-eight JCTs were placed in neonates with pneumothoraces. Neonates' birth weights ranged from 400 to 3,595 grams. All 38 tubes immediately relieved clinical signs of pneumothoraces. Thirty-five (92%) tubes immediately fully evacuated the pneumothoraces as evidences on chest radiograph. Twelve pneumothoraces partially reoccurred at a mean of 24 hours following JCT placement. These tubes were either irrigated or replaced. This newly configured chest tube functions effectively in the treatment of neonatal pneumothorax.

Chest Tubes↗
PubMed1991

A survey of theatre nurse's knowledge and ability in cardiopulmonary resuscitation. Part 1--The pilot study.

Theatre nurses are often faced with the problem of taking life-saving action when their patient suffers a cardiac arrest in theatre. This may happen when neither the anaesthetist or surgeon are immediately available to help--for example before, during or after some local anaesthetic procedures. In the first paper of this two part series, Jim Nelson described a pilot study he undertook which looks at the theatre nurse's skills and knowledge of this subject.

Cardiopulmonary Resuscitation↗