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Biomedical subjects

J Thompson

Publications and source records attributed to J Thompson.

At least 469 records · Page 26Linked to original sources
PubMed1992

Specification of the body plan during Xenopus gastrulation: dorsoventral and anteroposterior patterning of the mesoderm.

Although the mesoderm itself is induced at the blastula stage, its subdivision mainly occurs in response to further inductive signals during gastrulation. In the late blastula, most of the mesoderm has a ventral-type commitment except for the small organizer region which extends about 30 degrees on each side of the dorsal midline. During gastrulation, dorsal convergence movements bring the cells of the lateroventral marginal zone up near the dorsal midline and into the range of the dorsalizing signal emitted by the organizer. This dorsalizing signal operates throughout gastrulation, can cross a Nuclepore membrane, and is not mimicked by lithium, FGFs or activin. Anteroposterior specification also takes place during gastrulation and is probably controlled by a dominant region at the posterior end of the forming axis. We have studied the expression patterns in Xenopus of three members of the FGF family: bFGF, int-2 and a newly discovered species, eFGF. These all have mesoderm inducing activity on isolated animal caps, but are likely also to be involved with the later interactions. RNAase protections and in situ hybridizations show that the int-2 and eFGF mRNAs are concentrated at the posterior end, while bFGF is expressed as a posterior to anterior gradient from tailbud to head. Studies of embryos in which bFGF is overexpressed from synthetic mRNA show that biological activity is far greater when a functional signal sequence is provided. This suggests that int-2 and eFGF, which possess signal sequences, are better candidates for inducing factors in vivo than is bFGF.

Activins↗
PubMed1992

Postoperative nausea and vomiting.

One of the most common and distressing side effects after surgery performed under general anaesthetic is postoperative nausea and vomiting (PONV). Indeed, for many patients, PONV is the most distressing feature of their operation and some may become anxious about having another operation because of this. The medical and economic consequences of PONV can also be serious. This article looks at the incidence, causes, and current management of PONV, and the development of a new drug for the prevention and treatment of this.

Antiemetics↗
PubMed1992

Psychogenic periodic fever.

The present report concerns a 35-yr-old Caucasian male who had suffered from episodic fever of unknown origin over a period of 13 yr. Extensive investigation covering all the known causes of fever of unknown origin did not yield a diagnosis. Finally, a psychogenic cause was considered, and treatment with a psychotropic drug and relaxation therapy led to complete disappearance of the febrile periods.

Adult↗
PubMed1992

Recurrent intentional injury.

Recurrent intentional injury (RII) is a phenomenon that is often noted by those who treat the injured. The authors have observed two groups of assault-related injured patients at the District of Columbia General Hospital Level I urban trauma center to determine the magnitude of this phenomenon in the patient population, to examine the characteristics of such a group of patients, and to identify the risk factors that predispose to repeated assault-related injuries. In a retrospective group of 232 patients admitted over a 4-year period who had sustained penetrating abdominal trauma there were 76 (33%) patients who had been previously treated at our center for assault-related injury. A prospective study of 78 consecutive assault-related injured patients admitted during a 4-month period revealed that 35 patients (45%) had a history of previous hospitalization for injuries as a result of assault. Within the male group (72 patients) 49% exhibited RII. When comparing this group of patients with those patients who had no previous injuries secondary to assault, there was a significantly higher rate of unemployment for the RII group and no difference in educational level. Also, the RII group incurred significantly higher hospital charges when compared to the group of patients who had their first of such injuries ($9673 versus $6973). Efforts to reduce unemployment should be included in preventive strategies if the high incidence of assault-related injury is to be decreased.

Abdominal Injuries↗
PubMed1991

Purification and properties of fructokinase I from Lactococcus lactis. Localization of scrK on the sucrose-nisin transposon Tn5306.

Two electrophoretically distinct proteins with fructokinase (ATP:fructose-6-phosphotransferase) activity were detected in Lactococcus lactis subsp. lactis K1. Whereas fructokinase I was induced specifically by growth of the organism on sucrose, fructokinase II was derepressed during growth on ribose, galactose, maltose, and lactulose. Fructokinase I was purified about 1000-fold to electrophoretic homogeneity (specific activity 112 units/mg). The amino acid composition, N-terminal sequence, nucleoside triphosphate, and metal requirement(s) of the enzyme are reported. Ultracentrifugal analysis showed that the enzyme was primarily dimeric with subunits of 33.5 kDa (+/- 5%). When completely reduced, fructokinase I migrated as a single protein (Mr = 32,000) by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, but in the absence of reducing agent two polypeptides (apparent Mr = 29,000 and 31,000) were detected. Isoelectric focusing also revealed two polypeptides (pI 5.6 and 5.8), and both species catalyzed the phosphorylation of fructose and mannose. Hybridization studies showed that: (i) a sucrose-negative mutant lacking the fructokinase I gene (scrK) retained fructokinase II activity and (ii) scrK is closely linked to scrA and scrB which encode Enzyme IIScr and sucrose-6-phosphate hydrolase, respectively. In L. lactis K1, these genes and the N5-(1-carboxyethyl)-L-ornithine synthase gene (ceo) are encoded on the sucrose-nisin transposon Tn5306 in the order ceo-scrKAB.

Carbohydrate Metabolism↗
PubMed1991

Transposon-encoded sucrose metabolism in Lactococcus lactis. Purification of sucrose-6-phosphate hydrolase and genetic linkage to N5-(L-1-carboxyethyl)-L-ornithine synthase in strain K1.

Sucrose-6-phosphate hydrolase from Lactococcus lactis subsp. lactis K1-23 (formerly Streptococcus lactis K1-23) has been purified 600-fold to electrophoretic homogeneity. Purification of the enzyme was achieved by DEAE-Sephacel, phosphocellulose P-11, and gel exclusion (Ultrogel AcA 54) chromatography. The purified enzyme (specific activity 31 units/mg) catalyzed the hydrolysis of both 6-O-phosphoryl-alpha-D-glucopyranosyl-1,2-beta-D-fructofuranoside (sucrose 6-phosphate) and sucrose (Km = 0.1 and 100 mM, respectively). Ultracentrifugal analysis of sucrose-6-phosphate hydrolase indicated an Mr = 52,200. The purified enzyme migrated as a single protein during sodium dodecyl sulfate-polyacrylamide gel electrophoresis (Mr = 52,000). However, four distinct polypeptides were detected by analytical electrofocusing, and all four species hydrolyzed sucrose and sucrose 6-phosphate. The amino acid composition of sucrose-6-phosphate hydrolase, and the sequence of the first 12 amino acids from the NH2 terminus, have been determined. Hybridization studies with oligonucleotide probes show that the genes for sucrose-6-phosphate hydrolase (scrB), Enzyme IIScr of the phosphoenolypyruvate-dependent sucrose:phosphotransferase system (scrA), and N5-(carboxyethyl)ornithine synthase (ceo) are encoded by the same approximately 20-kilobase EcoRI fragment. This fragment is part of a large transposon Tn5306 that also encodes the nisin precursor gene, spaN, and IS904. In L. lactis ATCC 11454, spaN, IS904, scrA, and scrB (but not ceo) are encoded on a related transposon, Tn5307.

Amino Acid Oxidoreductases↗
PubMed1991

Hyperthyroidism associated with a thyroid adenoma in a dog.

Hyperthyroidism associated with thyroid adenoma was diagnosed in a dog. Typical clinical signs of hyperthyroidism were resolved with surgical excision of the adenoma. Hyperthyroidism in dogs usually is associated with thyroid carcinoma, which has a poor prognosis. This case emphasizes the importance of obtaining a histologic diagnosis of thyroid tumors in hyperthyroid dogs before giving a prognosis.

Adenoma↗
PubMed1991

Is adrenaline released by sympathetic nerves in man?

Radiotracer methods were used to measure the rates of regional release of adrenaline and noradrenaline into plasma in man. This was done as a partial test of a theory of essential hypertension pathogenesis which envisages an important cotransmitter function for neuronally released adrenaline. In healthy resting men no release of adrenaline could be detected from the heart, lungs or liver. Adrenaline was released into the right renal vein but an adrenal medullary source is suspected. With the relatively limited activation of the cardiac sympathetic outflow which accompanied mental challenge and isometric exercise, cardiac adrenaline release remained undetectable. During supine bicycle exercise, which increased cardiac noradrenaline release 10-30 fold, to a mean value of 197 ng/min, cardiac adrenaline release averaged 2.36 ng/min. In two clinical conditions associated with persistently elevated plasma adrenaline concentrations, cardiac failure and adrenaline-secreting phaeochromocytoma, regional release of adrenaline was clearly evident. Thus, in normal man during exercise, and in patients with cardiac failure at rest, adrenaline is released from non-adrenal sources, and probably from sympathetic nerves. Whether neuronal adrenaline release of the degree found would be sufficient to facilitate noradrenaline release, augment sympathetically-mediated cardiovascular responses and contribute to the development of arterial hypertension remains to be tested.

Adrenal Gland Neoplasms↗
PubMed1991

Distribution, antibiotic susceptibility and tolerance of bacterial isolates in culture-positive cases of endocarditis in The Netherlands.

During a two-year period data were collected nationwide in The Netherlands on 438 episodes of bacterial endocarditis (BE) in 432 patients. Of the strains isolated in these patients 419 were available for analysis. Of these, 326 were isolated in native valve endocarditis (NVE) and 93 in prosthetic valve endocarditis (PVE). Viridans streptococci, staphylococci and enterococci together constituted 87% of the isolates. More than 46% of the viridans streptococci consisted of Streptococcus sanguis. Enterococcus faecalis and Staphylococcus aureus were the predominant species in the late form of PVE. The majority of the viridans streptococci and haemolytic streptococci were highly susceptible to penicillin. Five of 35 strains of coagulase negative staphylococci were resistant to methicillin. Eleven percent of a random sample of the streptococci collected were tolerant to penicillin. After repeated exposure to a concentration gradient of an appropriate beta-lactam antibiotic, this figure increased to 49%. Of the staphylococci, 5-6% of the strains were tolerant before induction and 16-20% after induction. Of the Enterococcus strains (n = 40), 12.5% showed high-level resistance to one or more aminoglycoside.

Drug Resistance, Microbial↗
PubMed1991

Hospital mortality and long-term survival after pulmonary resection in the elderly.

We have studied the hospital mortality and long-term survival in two groups of patients: those between 50 and 69 years of age (group 1, n = 136) and those older than 70 years of age (group 2, n = 43). The two groups were similar in terms of the distribution of histological type and postsurgical staging. The patients were treated by either lobectomy or pneumonectomy; the lobectomy rate was similar in both groups: 61% and 51% (not significant). Hospital mortality for group 1 was 4.4% and for group 2, 6.9%. Mortality was higher in both groups after pneumonectomy compared with lobectomy, but this was not significant (group 1, 6.2% versus 1.9%; group 2, 9.1% versus 4.7%). Hospital mortality after pulmonary resection was greater in the elderly, but this was not significant (lobectomy: 1.9% [group 1] versus 4.7% [group 2]; pneumonectomy: 6.2% [group 1] versus 9.1% [group 2]. The overall long-term survival at 2 and 4 years was 62.3% and 50.0% for group 1 and 72.5% and 66.6% for group 2. We suggest that the operative risk in the elderly is not prohibitive and the long-term results are acceptable. Patients should not be denied operation on the basis of age alone.

Aged↗
PubMed1991

Giant cerebral aneurysm repair. Incorporating cardiopulmonary bypass and neurosurgery.

Since our initial experience on April 28, 1989, a total of nine patients have received treatment for giant cerebral aneurysm using cardiopulmonary bypass with deep hypothermia and circulatory arrest. The following data summarize our findings associated with these patients. The average patient's age was 46 years (range: 16 to 59 years of age). Seven patients were female, two were male. The procedure required approximately eight hours to complete with an average cardiopulmonary bypass time of 104 minutes (range: 60 to 140 minutes). Circulatory arrest time averaged 26 minutes (range, 12 to 45 minutes) with an average of 30 minutes (range: 10 to 62 minutes) required to cool the patient to below 18 degrees C (64 degrees F). An average of 54 minutes (range: 28 to 81 minutes) was required to warm the patient to a bladder temperature of 36 degrees C (96.8 degrees F). During the cooling period, five patients went into asystole spontaneously, four patients required bolus of 20 mEq of potassium chloride, and upon rewarming, spontaneous defibrillation occurred in six patients. Three patients were defibrillated without difficulty with external shock. The average number of blood products administered in each of the nine patients was 3.6 units of packed red blood cells, 3 units of fresh frozen plasma, and 6.5 units of platelets. Six patients recovered postoperatively without complication, and the recovery of three patients was affected by the complex anatomical location of the giant aneurysm. Cardiopulmonary bypass with deep hypothermia and circulatory arrest offers an alternative approach to the treatment of giant cerebral aneurysms considered inoperable by conventional techniques. The effectiveness of each procedure depends on the collaborative efforts of every member of the perioperative nursing team, the neurosurgical team, the cardiac surgical team, the neuroanesthesiology team, and the perfusionists. Careful planning and anticipation at every stage of the surgery can reduce surgical time, cardiopulmonary bypass time, and most importantly, circulatory arrest time.

Angiography↗
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

Role of tolerance in cloxacillin treatment of experimental Staphylococcus aureus endocarditis.

The role of Staphylococcus aureus tolerance was investigated in endocarditis in rats. The efficacies of cloxacillin, gentamicin, and a combination of the two were compared for animals infected with a tolerant strain, its kill-sensitive variant, or a nonisogenic nontolerant strain of S. aureus. Cloxacillin was significantly less effective for treating the tolerant than for the nontolerant strains. The addition of gentamicin to cloxacillin reduced bacterial numbers in endocardial vegetations for the tolerant strain comparable to the reduction by cloxacillin alone for the nontolerant strains, but had no additional effect for the nontolerant strains. Isolates from animals infected with the tolerant or nontolerant strains during antibiotic treatment remained tolerant or nontolerant. These results show that the in vitro phenomenon of tolerance is relevant in vivo.

Animals↗
PubMed1991

Safety and immunogenicity of live attenuated cold-adapted influenza B/Ann Arbor/1/86 reassortant virus vaccine in infants and children.

A cold-adapted (ca) influenza B reassortant vaccine consisting of two genes encoding the hemagglutinin and neuraminidase from wild-type influenza B/Ann Arbor/1/86 virus and the six internal RNA segments from influenza B/Ann Arbor/1/66 ca virus was evaluated in 18 seropositive and 57 seronegative infants and children. The ca reassortant was infectious in seronegative vaccinees, with an estimated 50% human infectious dose of 10(2.5) TCID50. Nasal wash specimens from vaccinees retained the temperature-sensitive phenotype, indicating that the virus was phenotypically stable after replication in fully susceptible children. The vaccine was highly immunogenic in the seronegative vaccinees; 54% of the seropositive vaccinees also developed an increase in serum antibody. The ca vaccine was well tolerated, with only a mild increase in upper respiratory tract symptoms seen in the seronegative vaccinees. These studies indicate that the B/Ann Arbor/1/86 ca reassortant is safe, immunogenic, and phenotypically stable in infants and children.

Antibodies, Viral↗