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Biomedical subjects

J Peters

Publications and source records attributed to J Peters.

At least 487 records · Page 27Linked to original sources
PubMed1988

Transient analysis of cardiopulmonary interactions. I. Diastolic events.

The etiology of the fall in left ventricular stroke volume (LVSV) with negative intrathoracic pressure (NITP) during inspiration has been ascribed to a reduction in LV preload. This study evaluated the effects of NITP with and without airway obstruction confined to early (ED), mid- (MD), or late diastole (LD) on the subsequent LVSV, anteroposterior (AP), and right-to-left (RL) aortic diameters (DAO) (series I, n = 6) as well as on phasic arterial blood flow out of the thorax (series II, n = 6) in anesthetized dogs. Transient NITP was obtained by electrocardiogram-triggered phrenic nerve stimulation. In series I, NITP applied for 60% of diastole with the airway obstructed caused decreases of LVSV during ED [-7.7 +/- 3.2% (SE) NS], MD (-11.7 +/- 3.9%, P less than 0.05), and LD (-14.6 +/- 1.5%, P less than 0.01) associated with significant increases of left ventricular end-diastolic pressures relative to both atmospheric and esophageal pressures during MD and LD. NITP increased DAO(AP) and DAO(RL), resulting in increases in diastolic aortic cross-sectional area by an average of 6.1-8.3% (P less than 0.01). Similar changes were seen with the airway unobstructed during NITP. In series II, NITP caused diminished diastolic antegrade carotid artery and/or descending aortic flow run off in all dogs. Transient retrograde arterial flows with NITP were observed in more than half of the animals consistent with increases in aortic diameters. We conclude that a decrease of intrathoracic pressure confined to diastole can 1) diminish the ensuing LVSV, presumptively reducing preload by ventricular interdependence; 2) distend the intrathoracic aorta; 3) diminish antegrade flow out of the thorax independent of effects on cardiac performance; and 4) cause transient retrograde carotid and aortic blood flow. The intrathoracic aorta and, presumably, the arterial intrathoracic vascular compartment can be viewed as an elastic container driven by changes in intrathoracic pressure.

Animals↗
PubMed1988

Transient analysis of cardiopulmonary interactions. II. Systolic events.

The etiology of the fall in left ventricular stroke volume (LVSV) and arterial pressure with a negative intrathoracic pressure (NITP) during inspiration is controversial. An increase in LV afterload produced by NITP has been proposed as one explanation but is difficult to evaluate if preload is also altered. To test the hypothesis that a systolic event alone, i.e., a change in LV afterload or contractility, can reduce LVSV during inspiration independent of changes in LV preload, a rapid transient NITP confined to systole was produced by electrocardiogram-triggered phrenic nerve stimulation in eight anesthetized dogs. Intrathoracic descending aortic diameters were measured by sonomicrometry to transduce qualitative changes in aortic transmural pressure. With the airway completely obstructed systolic NITP resulted in a decrease in LVSV (-8.1%, P less than 0.001) but an increase in the systolic anteroposterior (0.54 mm, P less than 0.01) and right-to-left (0.45 mm, P less than 0.01) aortic diameters compared with preceding beat. Similar significant changes were observed with the airway unobstructed. These observations are consistent with an increased afterload imposed on the LV reducing LVSV and egress of blood out of the thorax. Prolonging NITP to include both systole and diastole, a profound fall in LVSV is observed, consistent with the independent influences of systolic and diastolic events combining to diminish LVSV.(ABSTRACT TRUNCATED AT 250 WORDS)

Airway Obstruction↗
PubMed1988

Decreased slow-wave sleep and enlarged lateral ventricles in schizophrenia.

All-night electroencephalogram measures were evaluated against computed tomography scan measures, negative symptoms, and premorbid personality assessment in ten drug-free male schizophrenic patients. Computed tomography scan measures included ventricle brain ratio, cortical atrophy, and width of the third ventricle. Decreased stage-4 sleep was associated with enlarged VBR, poor premorbid functioning, and negative symptoms. Size of the VBR accounted for 58.5% of the variance in stage-4 sleep. Brain atrophy was associated with longer sleep latency but with less arousals once the patients were asleep. Rapid-eye-movement measures did not correlate significantly with any of the variables examined. Our data suggest that decreased slow-wave sleep and ventricle size are associated in schizophrenia.

Adult↗
PubMed1988

[Dynamic computerized tomography with contrast medium for improved differentiation between benign and malignant liver lesions].

Prolonged dynamic CT up to 32 minutes after intravenous bolus injection of 100 ml contrast medium improves the differentiation between benign (hemangiomas) and malignant (metastases) liver lesions. Our study shows that there are three distinct types of hemangiomas and that all three of them behave differently than metastases. Prolonged dynamic improves the problem of differentiation between hemangiomas and metastases but does not solve the problem completely.

Diagnosis, Differential↗
PubMed1987

Prenatal diagnosis of mosaic trisomy 9.

Mosaic trisomy 9 was detected in an amniotic fluid cell culture from a 40-year-old woman evaluated because of advanced maternal age. After counselling, parents elected to terminate the pregnancy. On autopsy the fetus was found to have hydrocephalus and a single kidney. The diagnosis of trisomy 9 mosaicism was confirmed in cultured skin fibroblasts. This is the third reported case of trisomy 9 mosaicism diagnosed prenatally.

Adult↗
PubMed1987

Chromosome maps of man and mouse, III.

Data on loci whose positions are known in both man and mouse are presented in the form of chromosomal displays, a table, and autosomal and X-chromosomal grids. At least 40 conserved autosomal segments with two or more loci, as well as 17 homologous X-linked loci, are now known in the two species, in which mitochondrial DNA is also highly conserved. Apart from the Y, the only chromosome now lacking a conserved group is human 13. Human 17 has a single conserved group which includes both short and long arms, and so may have remained largely intact in mammalian evolution. Human and mouse chromosomal maps show the approximate locations of homologous genes while the mouse map also shows the positions of translocations used in gene location.

Animals↗
PubMed1987

Role of beta-lactamase in in vivo development of ceftazidime resistance in experimental Pseudomonas aeruginosa endocarditis.

Two ceftazidime-resistant variants of Pseudomonas aeruginosa (PA-48, PA-60), obtained from cardiac vegetations of rabbits with endocarditis receiving ceftazidime therapy, were studied for mechanisms of resistance. Both resistant variants were stably derepressed for the type Id beta-lactamase, which was ceftazidime inducible in the parental strain (PA-96) used to initially infect the rabbits. There was no evidence of ceftazidime bioinactivation by the resistant strains, and their outer membrane permeabilities were comparable to those of the parental strain. No alterations were observed in patterns of outer membrane proteins or membrane lipopolysaccharides in the resistant variants as compared with the parental strain. Penicillin-binding protein patterns of the resistant variants revealed the absence of penicillin-binding protein 4 in both, with acquisition of a new protein of higher apparent molecular weight in PA-60. Calculation of the rate of appearance of ceftazidime in the periplasm at sub-MICs suggested that slow enzymatic hydrolysis of the beta-lactam, rather than nonhydrolytic trapping, was the major explanation for the induced resistance in vivo in strains PA-48 and PA-60.

Animals↗
PubMed1987

Analysis by gel electrophoresis, Western blot, and peptide mapping of protein A heterogeneity in Staphylococcus aureus strains.

To evaluate potential differences in protein A among Staphylococcus aureus strains, lysostaphin-solubilized cell wall proteins from 12 serologically distinct strains were analyzed by 7.5% sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (PAGE). Seven presumptive protein A variant identified in the 45- to 57-kilodalton range were then studied for qualitative binding affinities to nonimmune mouse and rabbit immunoglobulin G (IgG) by enzyme-linked immunoelectrotransfer blot. Essentially, all presumptive protein A variants demonstrated binding to both nonimmune rabbit and mouse IgG and had differential binding to mouse monoclonal IgG1 at pH 8.2 than at 5.5. Because of Fc-binding properties and molecular weight similarity to the well-characterized Cowan I protein A, these proteins appeared to represent protein A variants. Amino sugar analysis (less than 1%) by reverse-phase high-pressure liquid chromatography suggested that the apparent molecular weight differences in protein A were not due to associated mucopeptides. Further differences in protein A variants were studied by peptide mapping. Each of the seven protein A variants, distinguishable on SDS-PAGE, also produced distinct peptide cleavage patterns. In addition, two protein A variants indistinguishable on SDS-PAGE could be further subdivided by peptide mapping. These results suggest that SDS-PAGE analysis of protein A, particularly in conjunction with peptide mapping, may be useful in distinguishing distinct strains of S. aureus. Different protein A variants may also have unique functional or immunologic capabilities.

Bacterial Proteins↗
PubMed1987

Nucleotide sequence analysis of the gene encoding the Deinococcus radiodurans surface protein, derived amino acid sequence, and complementary protein chemical studies.

The complete nucleotide sequence of the gene encoding the surface (hexagonally packed intermediate [HPI])-layer polypeptide of Deinococcus radiodurans Sark was determined and found to encode a polypeptide of 1,036 amino acids. Amino acid sequence analysis of about 30% of the residues revealed that the mature polypeptide consists of at least 978 amino acids. The N terminus was blocked to Edman degradation. The results of proteolytic modification of the HPI layer in situ and Mr estimations of the HPI polypeptide expressed in Escherichia coli indicated that there is a leader sequence. The N-terminal region contained a very high percentage (29%) of threonine and serine, including a cluster of nine consecutive serine or threonine residues, whereas a stretch near the C terminus was extremely rich in aromatic amino acids (29%). The protein contained at least two disulfide bridges, as well as tightly bound reducing sugars and fatty acids.

Amino Acid Sequence↗
PubMed1987

[Behavior of serum zinc and selected plasma proteins following urologic operations].

In order further to contribute to the clarification of the serum-zinc level after larger abdominal urological interventions in 30 patients, in whom a supravesical derivation of the urine became necessary, serum-zinc determinations were performed twice preoperatively as well as on the 1st, 7th, 14th and 21st postoperative day. At the same time the proteins transferrin, coeruloplasmin and haptoglobin were determined in the serum. In other 45 patients who for a longer period lived with a supravesical derivation of the urine (uretero-intestinal anastomosis/ileum conduit) repeatedly serum-zinc determinations were performed, in order to establish a possible influence of the long-term urine derivation into the intact or excluded intestine on the serum-zinc content. On the 1st postoperative day a clear decrease of the serum zinc level by on an average 23% of the initial value were found. Coeruloplasmin and haptoglobin reacted with an increase of concentration. After a long-term derivation of the urine into the intact or excluded intestine normal serum-zinc concentrations were found.

Adult↗
PubMed1987

Malignant granular cell tumor.

A case of a granular cell tumor with a malignant behavior is described. Several repeated biopsy specimens, a resection specimen, and the metastatic lesions were compared with one another. Consecutive specimens showed increasing atypia. Electron microscopy of the metastatic lesions confirmed the granular cell nature of the tumor. The historic aspects of histogenesis are briefly discussed. The findings agree with a presently accepted origin from a primitive mesenchymal cell.

Humans↗
PubMed1987

Detection of fetal movement using Doppler ultrasound.

Using conventional cardiotocographic equipment with the ultrasound transducer placed to detect the fetal heart, we obtained unprocessed Doppler signals in the frequency range 13-70 Hz and used them to detect movements of the fetal trunk. In an assessment of maternal perception of fetal activity, we found that Doppler signals were associated with 739 of 780 appreciated movements (95%); however, 36% of all the Doppler signals were unaccounted for. A separate comparison of the Doppler signals against real-time ultrasound observations of fetal activity showed that 913 of 970 visualized trunk movements (94%) were associated with Doppler signals. Other Doppler signals were found to be due principally to fetal breathing and fetal hiccups. Appropriate processing of the Doppler signals obtained during antenatal cardiotocography may allow an objective assessment of fetal activity to be added to the fetal heart rate recording.

Female↗