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Biomedical subjects

J Gross

Publications and source records attributed to J Gross.

At least 19 recordsLinked to original sources
PubMed1992

Experimental model of smoking re-exposure: effects on relapse.

This study used a short-term laboratory model of smoking cessation and relapse to prospectively examine the effects of programmed self-administered smoking re-exposure during early abstinence. Sixty-seven subjects who had quit smoking for 3 days were randomly assigned either to smoke five cigarettes in their natural environment or to remain abstinent during the exposure period. The main hypothesis, that relapse to regular smoking would be quicker and more prevalent in exposed subjects, was supported. All exposed subjects had relapsed by 2 days post-exposure while 16% of unexposed subjects remained continuously abstinent throughout the 8 day study. This behavioral effect was seen in spite of acute decreases in reported desire to smoke and increases in guilt measured just after exposure. The study supports a role for stimulus re-exposure effects in the relapse process and suggests that additional research on experimental re-exposure is warranted.

Adult↗
PubMed1992

Lasting effects of postnatal hypoxia and saline injection on the striatal dopamine transport and their modification by gangliosides.

Hypobaric hypoxia (10 h daily, pO2 10 kPa) and saline administration (2.5 microliters/g body wt) from the 2nd till the 11th day of life both induced a long-lasting increase of the low-affinity dopamine (DA) uptake capacity in S1-fractions of the rat striatum. Additionally, the potassium-stimulated DA release was enhanced in adult control rats postnatally injected with saline. The administration of a mixture of bovine brain gangliosides (30 micrograms/g body wt) was found to prevent these effects. However, the kinetic constants of the DA uptake of hypoxic rats treated with gangliosides were reduced in comparison to untreated controls. Thus, the effects of gangliosides appear to differ between hypoxic and control conditions. The modification of the dopaminergic activity during brain development is discussed as a possible mechanism of the preventive effects of gangliosides against long-term cerebral dysfunctions following hypoxia or stress.

Animals↗
PubMed1992

Craniofacial applications for the Medpor porous polyethylene flexblock implant.

We describe use of flexblock, a newly designed Medpor porous polyethylene implant. This implant is ideally suited for repair of small to medium-sized cranial defects and correction of contour deformities. Medpor is used for a wide variety of maxillofacial procedures, and its properties make it an excellent choice for the cranium. It is a highly stable and somewhat flexible porous alloplast that has been shown to exhibit rapid soft-tissue and bone ingrowth. Flexblock, which was designed as an onlay for calvarial bone graft donor sites, has a smooth exterior surface and a series of conical ridges on its undersurface that enable easy bending, good contour adaptability, and suitable strength. We used the Medpor flexblock implant in 12 patients over 2 years for correction of contour deformities, cranial defects, and reconstruction of the supraorbital rim. There were no complications. Larger cranial defects and complex reconstructions can be performed using customized Medpor implants. The properties of Medpor and the flexblock design make this implant an excellent alternative to the existing methods of cranioplasty and cranial contour correction.

Adult↗
PubMed1992

Clinical evaluation of the safety of repetitive intraoperative defibrillation threshold testing.

One goal of the initial implantation procedure for a cardioverter defibrillator is determination of the configuration and patch location with the lowest defibrillation threshold (DFT). To determine the safety of multiple defibrillation tests, an analysis of the intraoperative defibrillation threshold tests (DFTT) in our patients was performed. In 84 patients, the mean number of DFT trials was 5.27; the mean number of joules received was 275.0. The maximum number of shocks in one implant procedure was 50 for a total of 4,895 joules without complications. Four patients received 30 or more DFT shocks without complication. There were two complications related directly to the DFTT: one patient with severe noninflammatory cardiomyopathy developed electromechanical dissociation and was subsequently resuscitated and survived; the second patient with severe triple vessel coronary artery disease suffered an intraoperative myocardial infarction during testing and eventually died 22 days postoperatively. All patients received an ICD unit; six patients had DFTs of greater than 20 joules. Based on our experience, we followed the clinical status (heart rate, blood pressure, ECG changes, fluid status, total anesthesia time) during the DFTT to determine the extent and duration of our testing protocol. Multiple shocks due to repositioning of the leads in a stable patient should not prohibit extensive testing as adverse consequences do not appear to be cumulative.

Electric Countershock↗
PubMed1979

Regulation of corneal collagenase production: stimulation of serially passaged stromal cells by blood mononuclear cells.

After three or more passages, stromal cell outgrowths from explants of normal rabbit corneas and from corneas previously burned with alkali did not produce collagenase until they were stimulated by the addition of rabbit blood-derived mononuclear cells or media conditioned by them. Normal stromal cells required stimulation by lymphocytes or their products from alkali-burned animals, whereas those from alkali-burned corneas were stimulated by lymphocytes from either normal or alkali-burned rabbits.

Animals↗
PubMed1979

Procollagen segment-long-spacing crystallites: their role in collagen fibrillogenesis.

Naturally occurring segment-long-spacing crystallites of procollagen collagen have been found in the culture medium of fibroblasts from chick embryo tendon, human skin, and dermatosparaxic calf skin; in whole-mount preparations of cultured human skin fibroblasts; in homogenates of lathyritic chick embryo tendon, cartilage, and cornea; and in a partially purified preparation of procollagen. Bundles of similar aggregates occurred within secretory vacuoles of collagen-synthesizing fibroblasts and chondrocytes. These observations suggest that fibroblasts and chondrocytes secrete procollagen assemblies that are stable in the extracellular environment. We propose that subsequent enzymatic processing is accompanied by direct incorporation of such structures into the assembling fibril, which then may be considered as an n X 67 nm staggered array of segment-long-spacing crystallites.

Animals↗
PubMed1979

Hyaluronate and invasiveness of the rabbit V2 carcinoma.

We propose that hyaluronate, a major component of extracellular matrices through which cells migrate during embryonic tissue development and in regenerative processes, is also concentrated in the environment through which neoplastic cells invade local host tissues and may facilitate this process. The hyaluronate content of invasive V2 carcinoma grown in rabbit was found to be 3-4 times greater than that of the same tumor grown in the nude mouse, in which it is noninvasive. Moreover, hyaluronate concentrations were most elevated in the connective tissue interface between the tumor mass and the neighboring host tissue in the invasive rabbit tumors. The particular site of tumor implantation in the rabbit or nude mouse did not affect the concentrations of hyaluronate in either the parenchyma or the surrounding connective tissue. Similar values were obtained for neoplasms grown in muscle, which normally contains little hyaluronate, and in subcutaneous tissue, which is relatively rich in this glycosaminoglycan.

Animals↗
PubMed1979

TSH synthesis and release in the thyroidectomized rat: b) effect of T3.

The time and dose dependent effects of T3 on the anterior pituitary (AP) TSH release and synthesis were studied in rats 5 days after thyroidectomy (T-5d). T3, in various doses, was injected iv to animals which were kileed at various times later. Plasma and AP TSH were measured. T3 lowered plasma TSH to a minimum within 3 h. An inverse linear relationship was found between T3, up to 634 +/- 134 ng/100 g b.w. (mean +/- SD) and plasma TSH. Higher doses of T3 did not lower plasma TSH any further. At T3 of 634 +/- 134 ng/100 g b.w. the specific AP binder was calculated to be 68% to 90% saturated; thus suggesting a relationship between occupancy by T3 of the AP binder and the regulation of TSH release. The TSH release and synthesis rates were compared after 0.5 micrograms, 1 microgram and 25 micrograms T3. All three doses of T3 suppressed the release as well as the synthesis. The effect of T3 on the synthesis rate, however, lagged behind the effect on the release both in time and magnitude.

Animals↗
PubMed1979

[In vitro investigations of microphages function in patients with chronic mucocutaneous candidosis (author's transl)].

In five patients with either familial or non-familial type of chronic mucocutaneous candidosis some properties of phagocytic function of the polymorphonuclear leucocytes (PMNL) have been studied in vitro. In each of the patients there were found: a) a decreased chemotactic activity of PMNL, b) a weakness of intake and of intracellular destruction of Candida albicans cells by PMNL, c) an impairment of phagocytosis and intracellular killing of Candida albicans as well of Staphylococcus aureus by PMNL. The rate of phagocytosis of heat-inactivated Candida albicans cells by PMNL was normal in each case. In the serum of two patients a phagocytosis inhibiting factor is supposed to exist. In PMNL of 3 patients a defective activity of NADH-dependent oxidase was found. The occurrence of hereditary CMCC in a father and his two daughters points to an autosomal dominant trait, whereas in most cases of familiar CMCC hitherto described an autosomal recessive mode of transmission was found.

Adult↗
PubMed1979

[Erythropoietin and erythropoiesis inhibition factor in the newborn and infants with cyanotic heart abnormalities].

In the present study, hematocrit, pO2 in the capillary blood, reticulocyte count, erythropoietin activity in plasma and activity of the erythropoiesis inhibition factor in 24-h collective urine were determined in newborns and infants with cyanotic malformations of the heart (transpositions of the big arteries). The plasma of the healthy newborns shows immediately after birth an erythropoietin activity below 1%, as measured by the 59Fe incorporation. The erythropoietin activity of the plasma of infants with cyanotic malformations of the heart is enhanced up to the 14th day of life. In the period of day 14--30 it corresponds to the values of healthy newborns despite the persistence of hypoxia. After the 30th day of life there is again demonstrable an increased erythropoietin activity in the plasma of infants with cyanotic malformations of the heart. Obviously, the low values of 59Fe incorporation from day 14--30 are due to the occurrence of the erythropoiesis inhibition factor. In the urine of infants with cyanotic malformations of the heart there could be demonstrated distinct inhibitions of the stimulated erythropoiesis of the polycythemic mouse. The present studies suggest that the erythropoiesis inhibition factor occurs in postnatal development irrespectively of the degrees of O2-supply of the tissue, and is possibly dependent on the gestational age.

Aging↗
PubMed1979

[Pre- and postoperative erythrocyte volume distribution curves in children with cyanotic heart defects].

The behaviour of the volume distribution curves (VVK) of red blood cells in children with cyanosed organic heart defect is reported by taking preoperative and postoperative observations as a basis. MCV determined from the volume distribution curve amounts to 80.3 micron3. If the volume distribution curves of the preoperative patient group are compared with the postoperative patient group (4 months) by means of the criteria DSmax, DS, inclination and dispersion, no significant changes can be identified. Therefore, shifting maturity divisions cannot be assumed in children with cyanosed organic heart defects, even in those with a preoperative hypoxia of a high degree.

Adolescent↗
PubMed1978

Covalent structure of collagen: amino acid sequence of chick skin collagen alpha1(1)-CB6B.

The amino acid sequence of the peptide alpha1(I)-CB6B, the carboxyl-terminal peptide containing 91 residues of alpha1(I) chain of chick skin collagen, is described. The amino acid sequence was determined by automated Edman degradation of intact peptide plus its tryptic and thermolytic peptides. The comparison of this sequence with the corresponding segment of previously published alpha1(I)-CB6 of calf skin collagen showed a sequence identity of 90%.

Amino Acid Sequence↗