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Biomedical subjects

J Peters

Publications and source records attributed to J Peters.

At least 469 records · Page 26Linked to original sources
PubMed1989

X-inactivation of the Sts locus in the mouse: an anomaly of the dosage compensation mechanism.

The behaviour of the X- and Y-borne Sts locus has been studied in male and female mice. There was considerable heterogeneity in STS activity between inbred mouse strains, with a four fold difference in activity between the highest (101/H) and lowest (Ju/Ct) activity strains, which can be interpreted in terms of allelic differences. In all inbred strains male STS levels were higher than those of female STS levels and in the majority of strains tested male STS levels were nearly twice as high as female levels. Reciprocal crosses between C3H/HeH and the STS-deficient substrain, C3H/An, demonstrated that activities of the X- and Y-borne genes in males are essentially the same and this suggested that the lower STS level in females derives from X-inactivation of the locus. The possibility that hormonal differences could instead be responsible for the lower activity in females was ruled out by the findings that (a) castration of males did not reduce their STS levels and (b) sex-reversed males, X/X Sxr, had STS levels typical of females. Final proof that the mouse Sts locus can be subject to the X-inactivation process was provided by the observation that XX females had STS levels that were only slightly (20%) higher than those of XO females. The difference may indicate incomplete inactivation of the locus. Linkage data verifying the location of Sts on the distal end of the X chromosome are provided.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Effects of segmental thoracic extradural analgesia on sympathetic block in conscious dogs.

To test the hypothesis that segmental thoracic extradural block causes sympathetic denervation caudally beyond dermatomes rendered analgesic, we have measured regional skin temperatures in six conscious dogs after upper thoracic, mid thoracic, and lumbar extradural injection of 0.5% bupivacaine 0.5, 1 and 2 ml cumulatively (total dose: 3.5 ml) given at 45-min intervals. Dogs were studied at constant ambient and rectal temperatures. Upper thoracic extradural injections resulted in a significant increase in skin temperatures on both the front (+1.4 (SEM 0.2) degrees C) and hind paw (+1.4 (0.3) degrees C), while the area of analgesia was confined to the upper trunk. With lumbar extradural injection, skin temperatures increased significantly (+2.0 (0.5) degrees C) on the lower extremities only. Mid thoracic injection significantly increased both front (+2.4 (0.9) degrees C) and hind paw (+2.2 (0.6) degrees C) skin temperatures, but decreased temperatures on the thorax (-0.9 (0.2) degrees C) and abdomen (-1.0 (0.2) degrees C), reversing the normal temperature gradient along the body axis. Irrespective of the injection site, skin temperatures on the trunk failed to increase or even decreased significantly. These data suggest that small doses of local anaesthetics applied to the extradural space of conscious dogs cause increased lower extremity skin temperatures caudal to areas unresponsive to pinprick stimulation when injected at a high thoracic level, and decreased trunk skin temperature even in analgesic areas, so that skin temperature measurements are unlikely to reflect purely sympathetic efferent activity on the trunk. Upper thoracic segmental extradural analgesia induced a decrease in sympathetic tone distal to the area of analgesia.

Anesthesia, Epidural↗
PubMed1989

Osteomorphological features of the appendicular skeleton of gazelles, genus Gazella Blainville 1816, bohor reedbuck, Redunca redunca (Pallas, 1767) and bushbuck, Tragelaphus scriptus (Pallas, 1766).

Examined the osteomorphological features of the appendicular skeleton of Grant's gazelle (Gazella granti), bohor reedbuck (Redunca redunca) and bushbuck (Tragelaphus scriptus). Osseous remains of these medium sized antelopes are often encountered in African late Quaternary archaeological sites, but their specific identification poses considerable problems to the archaeozoologist. A key has been developed to meet this recurrent problem and a number of diagnostic osteomorphological features, allowing a distinction between the bovids mentioned, are established. The osteomorphological characteristics, typical for Grant's gazelle have also been observed in the eight other extant African gazelles and in two Asian species, the goitred gazelle (Gazella subgutterosa) and the mountain gazelle (Gazella gazella).

Animals↗
PubMed1989

Chromosome maps of man and mouse. IV.

Current knowledge of man-mouse genetic homology is presented in the form of chromosomal displays, tables and a grid, which show locations of the 322 loci now assigned to chromosomes in both species, as well as 12 DNA segments not yet associated with gene loci. At least 50 conserved autosomal segments with two or more loci have been identified, twelve of which are over 20 cM long in the mouse, as well as five conserved segments on the X chromosome. All human and mouse chromosomes now have conserved regions; human 17 still shows the least evidence of rearrangement, with a single long conserved segment which apparently spans the centromere. The loci include 102 which are known to be associated with human hereditary disease; these are listed separately. Human parental effects which may well be the result of genomic imprinting are reviewed and the location of the factors concerned displayed in relation to mouse chromosomal regions which have been implicated in imprinting phenomena.

Animals↗
PubMed1989

S-layer protein gene of Acetogenium kivui: cloning and expression in Escherichia coli and determination of the nucleotide sequence.

Acetogenium kivui is anaerobically growing thermophilic bacterium with a gram-positive type of cell wall structure. The outer surface is covered with a hexagonally packed surface (S) layer. The gene coding for the S-layer polypeptide was cloned in Escherichia coli on two overlapping fragments by using the plasmid pUC18 as the vector. It was expressed under control of a cloned Acetogenium promoter or the lacZ gene. We determined the complete sequence of the structural gene. The mature polypeptide comprises 736 amino acids and is preceded by a typical procaryotic signal sequence of 26 amino acids. It i weakly acidic, weakly hydrophilic, and contains a relatively high proportion of hydroxyamino acids, including two clusters of serine and threonine residues. An N-terminal region of about 200 residues is homologous to the N-terminal part of the middle wall protein, one of the two S-layer proteins of Bacillus brevis, and there is also an internal homology within the N-terminal region of the A. kivui polypeptide.

Amino Acid Sequence↗
PubMed1989

Negative intrathoracic pressure decreases independently left ventricular filling and emptying.

The mechanism for the fall in left ventricular (LV) stroke volume with normal and obstructed inspiration is controversial with changes proposed in LV preload and afterload. During respiration extending over several cardiac cycles, changes in both LV filling and emptying could occur, rendering demonstration of any responsible mechanism difficult. To evaluate the independent effects of negative intrathoracic pressure (NITP) on LV filling and emptying, we have analyzed the effects of NITP confined to either diastole or systole using electrocardiogram (ECG)-triggered phrenic nerve stimulation in six anesthetized closed-chest dogs. Lung volume was either maintained by completely obstructing the airway or allowed to increase during NITP. With diastolic NITP and the airway obstructed during phrenic nerve stimulation, LV filling volume (integrated mitral flow) significantly decreased (-37 +/- 6.1% SE) associated with increases in LV and right atrial filling pressures at end diastole relative to both atmospheric and esophageal pressures. Right atrial pressure relative to either atmospheric or esophageal pressure increased significantly more than left atrial pressure. The ensuing LV stroke volume (integrated ascending aortic flow) decreased significantly (-30.8 +/- 5.9%). With NITP confined to systole and at constant LV preload, LV stroke volume also decreased (-12.9 +/- 2.5%) associated with an increase in LV systolic pressure relative to esophageal pressure. Similar significant changes were observed despite a smaller fall in esophageal pressure when lung volume was allowed to increase during either diastolic or systolic NITP. We conclude that 1) NITP confined to diastole decreases LV filling and the ensuing LV stroke volume, most likely by ventricular interdependence; 2) NITP confined to systole also decreases LV stroke volume, presumptively by imposing an increased afterload on the LV; 3) both diastolic and systolic mechanisms should contribute to a decreased LV stroke volume during normal and obstructed inspiration; and 4) if the effects of intrathoracic pressure changes were to extend over several cardiac cycles, mechanisms exist to account for either increases or decreases in LV volumes.

Airway Obstruction↗
PubMed1989

Local abnormalities of coagulation and fibrinolytic pathways that promote alveolar fibrin deposition in the lungs of baboons with diffuse alveolar damage.

Because alveolar fibrin is a prominent histologic feature of diffuse lung injury in baboons, we hypothesized that local abnormalities of pathways of fibrin turnover would favor fibrin deposition in the alveolar space. To test this hypothesis, procoagulant and fibrinolytic activities were characterized in serial bronchoalveolar lavage (BAL) of baboons with evolving diffuse alveolar damage (DAD) induced by exposure to 100% O2. BAL procoagulant activity, characterized mainly as the tissue factor-Factor VII complex, was markedly increased after induction of DAD. Extrinsic pathway inhibitor was likewise increased in BAL during evolving DAD but was insufficient to control coagulation. Urokinase-like fibrinolytic activity was usually detectable in baseline BAL but was undetectable after 7 d of O2. DAD BAL contained significantly increased plasminogen levels, plasmin inhibitor activity sufficient to neutralize all plasmin produced by BAL plasminogen activator found in control BAL and detectable plasminogen activator inhibitor-1. Antiplasmin activity was due, in part, to increased alpha 2-antiplasmin. These changes correlated with quantitatively increased alveolar fibrin deposition demonstrated by histologic and morphometric analyses. Multiple abnormalities of pathways of fibrin turnover occur concurrently in the alveolar compartment of the lungs of baboons with DAD, which collectively predispose to diffuse alveolar fibrin deposition.

Animals↗
PubMed1989

[Combination fractures of the pelvic girdle: comparison of CT with the conventional pelvic image].

102 polytraumatised patients with pelvic fractures were studied by conventional x-rays of the pelvis as well as by computed tomography to obtain detailed information on type and degree of the fractures. We paid particular attention to acetabular and sacral fractures and combinations thereof. We found that only computed tomography enabled us to precisely define type and degree of pelvic injury. We thus draw the conclusion that each patient with proven or suspected pelvic injury should be subjected to a CT study to enable the surgeon to plan his therapy-conservative or surgical-to the best benefit of the patient.

Acetabulum↗
PubMed1989

Immunoradiometric assay of carcinoembryonic antigen with use of avidin-biotin labeling.

In evaluating an enzyme-linked immunoassay of carcinoembryonic antigen (CEA) we found that the IgG fraction of polyclonal anti-CEA antibodies (DAKO) bound very well to the walls of polypropylene test tubes. We therefore developed an immunoradiometric CEA assay based on this binding of polyclonal anti-CEA antibody. We biotinylated a commercially available monoclonal antibody (Hybritech) and bound this to the CEA-anti-CEA bound to the tube wall. For detection we used 125I-labeled streptavidin. In comparison with several immunoassays for CEA this system offered several advantages such as greater linearity of the standard curve (from 0 to 74 micrograms/L), a steeper dose-response curve, and smaller coefficients of variation in the clinically useful range. This assay system may be used for other large molecules, so that only one tracer, the 125I-labeled streptavidin, has to be labeled; thus the technique seems suited for several different assays.

Antibodies, Monoclonal↗
PubMed1989

[Appendicitis in the computed tomographic image].

29 patients with unclear symptoms in the right lower abdomen received a CT-examination in an attempt to prove or exclude appendicitis. In almost all cases it was possible to demonstrate the inflammatory process in the appendix itself (size of the organ). More diagnostic information was obtained by careful examination of the accompanying reactions of the cecum, the mesenteriolum, the fascia and other neighboring organs. Thus CT is a valuable tool in the diagnosis of appendicitis and facilitates the decision for or against an appendectomy, which otherwise may be very difficult.

Acute Disease↗
PubMed1988

[Blood titers of the bovine respiratory syncytial virus].

The variations in titre of the bovine respiratory syncytial virus were determined in young calves. As soon as maternal immunity was no longer detectable, the calves were inoculated. Inoculations in animals which were less than four months of age gave rise to only a slight increase in titres. The increases in titre in calves over this age varied markedly.

Age Factors↗
PubMed1988

Lung extravascular volume during venovenous bypass with extracorporeal CO2-removal in dogs.

Extracorporeal circulation can cause lung damage, which would be especially counterproductive during extracorporeal gas exchange for the treatment of acute respiratory failure. To test the hypothesis that partial venovenous bypass with extracorporeal CO2-removal combined with low-frequency positive pressure ventilation (ECCO2R-LFPPV) can adversely affect lung fluid balance, extravascular thermal lung volume (ETV) and hemodynamics were assessed before, during and after ECCO2R-LFPPV in normal closed chest dogs. In series I dogs (n = 6) subjected to 10 h of ECCO2R-LFPPV, ETV did not change significantly from control (7.1 ml/kg +/- 0.99 SE) during or after bypass. Gravimetric extravascular lung water and lung histology after bypass were found to be normal. In series II dogs (n = 5), subjected to shorter periods of ECCO2R-LFPPV, ETV also remained unchanged. In contrast to previous reports using sheep, pulmonary arterial hypertension during bypass was not observed. Thus, ECCO2R-LFPPV was not associated with increased lung water, pulmonary hypertension or morphological lung changes under the conditions studied and does not seem to cause lung damage in normal lungs.

Animals↗
PubMed1988

Extracorporeal CO2-removal with a heparin coated artificial lung.

Treatment of severe acute respiratory failure with extracorporeal gas exchange necessitating near complete systemic anticoagulation requires a delicate balance to be maintained between disseminated intravascular coagulation and hemorrhagic complications. The present study describes our first experience using a heparin coated extracorporeal artificial lung and circuitry during clinical extracorporeal CO2 removal. In spite of a partial thromboplastin time and activated clotting time within or close to the normal range, neither laboratory evidence for disseminated intravascular coagulation induced by the extracorporeal circuit nor thrombi in the pulmonary vasculature were found. Scanning electron microscopy of the heparin coated hollow fiber gas exchanger demonstrated only minor deposits on the surface. Use of a heparin coated artificial lung may enhance the margin of safety of extracorporeal gas exchange and ultimately broaden its indications.

Acute Disease↗
PubMed1988

Calcium and inorganic phosphate secretion of rat ileum in vitro. Influence of uremia and 1,25 (OH)2D3 inhibition.

The unidirectional ileal transport of calcium (Ca) and inorganic phosphorus (Pi) of rats was measured in vitro with the modified Ussing technique. Animal preparation included 5/6 nephrectomy and EHDP treatment. They were compared to controls as well as to 1,25 (OH)2D3 supplemented rats. The results show that the ileum is a secretory organ for Ca and Pi, the serosa to mucosa transport (Jsm) exceeds the mucosa to serosa transport (Jms). Ca and Pi transport in sm direction is 1,25 (OH)2D3 independent but exhibits a mutual strong correlation. Our observations together with published data are in favor of mainly paracellular, non electrogenic sm transport of both ions. However, the factor controlling sm transport of Ca and Pi remains unidentified. The mucosa to serosa transport (Jms) in the ileum is low for both ions. Ca ms is stimulated by 1,25 (OH)2D3, Pi ms is unchanged.

Animals↗
PubMed1988

Regional skin temperatures associated with total sympathetic blockade in conscious dogs.

Multiple regional skin temperatures were measured continuously before and after complete sympathetic nerve block by extradural anaesthesia in conscious dogs in environmental temperatures slightly below (22.4 (SEM 0.4) degrees C) and slightly above (27.2 (0.4) degrees C) the thermoneutral range. In the cold environment, skin temperature increased in the distal (+2.13 degrees C, P less than 0.001) and proximal (+1.1 degrees C, P less than 0.02) front limbs and distal (+3.25 degrees C, P less than 0.001) and proximal (+1.72 degrees C, P less than 0.001) hind limbs, but decreased on the chest (-0.83 degrees C, P less than 0.01) and abdomen (-0.67 degrees C, P less than 0.002). Similar changes (all significant) were seen in the warm environment, although the effects were smaller. Rectal temperature did not change during the experiments. Arterial pressure decreased in both groups after denervation, but was the same in the denervated state regardless of ambient temperature. Our results are incompatible with increased sympathetic discharge from unblocked regions being a dominant factor in the decrease in trunk skin temperature above and within the analgesic areas, and demonstrate a substantial contribution of the sympathetic nervous system to the maintenance of the normal skin temperature gradient along the long axis of the body.

Anesthesia, Epidural↗