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Biomedical subjects

A Jansen

Publications and source records attributed to A Jansen.

At least 127 records · Page 7Linked to original sources
PubMed1988

Rebreathing to cope with hyperventilation: experimental tests of the paper bag method.

To explore if and how the common rebreathing (paper bag) approach to hyperventilation works, two experiments were carried out. In the first experiment, 12 normal volunteers, aware of the common physiological rebreathing rationale, were twice asked to overbreath intensely and then either to rebreath or to restart normal ventilation. Alveolar CO2 increased more quickly and physical symptoms disappeared earlier in the rebreathing condition. The second experiment had a similar design; however, this time the subjects were led to believe that, after both hyperventilation provocation tests, they were rebreathing in a semiclosed tube system. On one of the occasions, the tube system was, in fact, open. The CO2 restoration again differed in the two conditions. In this second experiment, the moment of symptom disappearance was not significantly earlier in the rebreathing condition. The combined results of the studies suggest that expectation and suggestion play a role in the effects of rebreathing approaches on hyperventilation.

Adult↗
PubMed1988

Reduction of salmonella infection of broilers by spray application of intestinal microflora: a longitudinal study.

The Nurmi concept for diminishing salmonella infection of poultry by application of gastrointestinal microflora from adult birds into newly hatched chicks was tested in a field study in which 8 million broilers were involved. Half of the 284 flocks was treated in the hatchery by spray application of an undefined microflora propagated in SPF chicks. A significant reduction in salmonella-contaminated flocks, as well as in the number of infected broilers in these flocks was demonstrated. No undesirable side effects were detected. It was concluded that hygienic improvements in transportation and slaughtering of broilers are needed in order to maintain the reduced salmonella contamination rate.

Animals↗
PubMed1985

An international survey of medical school programmes on nuclear war.

Many medical organizations have acknowledged the responsibility of doctors to educate health professionals and the public about the medical, social and ecological consequences of nuclear war. Medical schools have begun the development of programmes on these topics. A total of 1130 medical schools in thirty-one countries were surveyed about their presentation of nuclear-war-related subject matter. Eighty-three (49%) of the 168 schools that responded indicated that they offered an activity on medical aspects of nuclear war. Thirty-two per cent of the programmes consisted of one or more hours in an existing required course. Twelve per cent offered an elective course solely concerned with nuclear war. Although only 15% of the schools responded many of the replies indicated interest in learning more about the programmes of other schools and inquired if curriculum or teaching materials were available. Through the survey it was learned that textbooks and other learning resources have been prepared. Survey information suggests that knowledge of nuclear weapons effects is associated with a reluctance to countenance nuclear war.

Curriculum↗
PubMed1984

Intraperitoneal and intravenous cefoperazone kinetics during continuous ambulatory peritoneal dialysis.

Serum cefoperazone (CFP) kinetics after a 1-gm dose added to the peritoneal dialysate were followed in seven patients undergoing continuous ambulatory peritoneal dialysis (CAPD). In a randomized order five of the seven patients received 1 gm IV CFP. Serum samples were collected over 10 hr during one dialysate exchange interval. CFP concentrations were determined by HPLC. After intravenous dosing CFP mean peak and 6-hr serum concentrations were 104.2 +/- 29.1 micrograms X ml-1 and 8.5 +/- 3.8 micrograms X ml-1, mean body clearance was 80 +/- 20 ml X min-1, and mean apparent volume of distribution was 14.6 +/- 3.2 l. The elimination rate constant (kel) varied from 0.29 to 0.38 hr-1 and was almost identical to kel derived from intraperitoneal application (range 0.29 to 0.42 hr-1). Instillation of CFP with the peritoneal dialysate resulted in a rapid rise of serum levels (Tmax = 1.9 +/- 0.7 hr; absorption rate constant ka = 0.68 +/- 0.11 hr-1), and sufficient CFP concentrations (Cmax = 33.2 +/- 5.3 micrograms X ml-1), were maintained over 6 hr (C6 hr = 17.3 +/- 5.8 micrograms X ml-1). Mean systemic availability of intraperitoneal CFP was 95% +/- 12%. Intraperitoneal administration of CFP in patients undergoing CAPD resulted in serum levels of CFP adequate for systemic treatment of bacterial infections.

Adult↗
PubMed1984

Human pancreatic growth hormone releasing factor (hpGRF-1-40) stimulates GH release in the ovine fetus.

The effects of growth hormone-releasing factor, hpGRF (1-40), on plasma GH levels were studied in chronically catheterized ovine fetuses between 71 to 134 days of gestation. The basal ovine (o) GH levels in the fetus ranged between 41 - 144 ng/ml, while values in the ewe were often less than 6 ng/ml. hpGRF (1-40), 5 micrograms/kg infused into a fetal vein, markedly stimulated GH release in all nine fetuses. The maximum increase above pretreatment levels (net increases) ranged from 65 ng/ml to 498 ng/ml, with a mean net increase of 229 ng/ml. The responses of oGH in fetuses at younger gestational age appeared to be greater than in older fetuses. Mean plasma oPRL did not change after hpGRF infusion. These results indicate that somatotrophs in fetal sheep in mid- and late gestation have receptors for GRF, and GH secretion may be modulated by GRF at this stage of gestation.

Animals↗
PubMed1983

Some social background variables among smoking and non-smoking primiparae.

Of a population of 2,427 Norwegian primiparae, 62.7% were non-smokers, 23.0% smoked fewer than 10 cigarettes a day, and 14.3% smoked 10 or more a day. There was a significant correlation between smoking in pregnancy and age below 20 years, unmarried or previously married status, and poor education (p less than 0.001). Poor housing is of less importance. The mean age of smokers (24.0 years) was significantly lower than that of non-smokers (25.8 years) (p less than 0.001). The overall incidence of smoking in pregnancy was not significantly different from that in the normal population, but pregnant women under 20 smoked significantly more and those older than 24 significantly less, compared with their counterparts in a normal population (p less than 0.01).

Adolescent↗
PubMed1981

Transport in quantitative structure-activity relationships. VI: Relationship between transport rate constants and partition coefficients.

The transport rate constant of a drug partitioned in a two-phase system from an aqueous to an organic phase (k1obs) and vice versa (k2obs) is a function of the partition coefficient P and of a solvent system-dependent parameter beta. Drug transport is shown to be independent of molecular structure for a number of arbitrary compounds.

Biological Transport↗
PubMed1981

Regular fetal breathing induced by pilocarpine infusion in the near-term fetal lamb.

We report that pilocarpine, a cholinergic drug, stimulated regular sustained breathing movements in 10 near-term fetal lambs with chronically implanted catheters in the carotid artery, jugular vein, and trachea. With increasing doses of pilocarpine (0.1-5.9 mg), there was an enhanced respiratory response as measured by the duration of continuous breathing movements (14 +/- 12 min, increasing to 82 +/- 50 min; mean +/- SD), and the mean tracheal pressure per breath at end inspiration during the first 2 min after drug infusion (18 +/- 5, increasing to 38 +/- 12 mmHg). The mean pressure per breath during the control periods was 8 +/- 3 mmHg. There was no significant change in the breath frequency with increasing drug dose. A similar breathing response was not seen with epinephrine, suggesting that pilocarpine does not act by stimulating release of endogenous catecholamines. There was no fetal breathing response to pilocarpine infusion in atropine-pretreated fetal lambs, suggesting tha pilocarpine acts through a muscarinic mechanism. In eight acute experiments on exteriorized fetal lambs, we measured responses to pilocarpine before and after carotid sinus nerve ligation. The response to pilocarpine was abolished by sinus nerve section, suggesting possible mechanisms whereby pilocarpine may stimulate fetal breathing: the drug may increase peripheral chemoreceptor output, may sensitized the central respiratory centers to peripheral chemoreceptor input, of both.

Animals↗
PubMed1981

Clinical applications of magnetic rings in colorectal anastomosis.

Based upon experiments on animals, an anastomotic apparatus, consisting of two magnetic rings of polymer bonded, rare earth cobalt magnets embedded in polyester, was developed. There are three types of polyester device with diameters of 25, 28, and 30 millimeters, respectively. The force between the magnets varied between 2.5 Newtons at 4 centimer separation and 11.8 Newtons at union. For the low colorectal anastomosis, a magnet holder, connecting rod and spherical cap were developed. The aim of the technique is a quick restoration of the underbroken submucosal intestinal cylinder by optimal circular apposition of the submucosal layer. The working mechanism is based upon progressive compression, leading to necrosis of the intermediate mucosal and submucosal layers by increasing the magnetic force while intestinal healing takes place. After seven to 12 days, the magnets cut through the disappear from the anastomotic region by intestinal peristalsis. From the initial series of 21 patients, 11 resections of the sigmoid colon and nine low anterior resections were performed. Dehiscence of the suture line was noted in two instances. One patient required reoperation. The other patient had a small area of dehiscence at the suture line after evacuation of an infected hematoma with a further uncomplicated course. One patient died on the third postoperative day of recurrent myocardial infarction. In the other 18 patients, primary intestinal healing was demonstrated roentgenologically and sigmoidoscopically.

Aged↗
PubMed1981

The importance of the apposition of the submucosal intestinal layers for primary wound healing of intestinal anastomosis.

This study was undertaken to examine the importance of the apposition of the submucosal layers in healing of the intestinal anastomosis. On 18 mongrel dogs, weighing between 8 and 15 kilograms, four anastomoses were performed on the small intestine. Two with a conventional anastomosis and two with rings of polyester-polyethyleneterephtalate, containing small Ticonal magnets. The force between the rings with the magnets varied from 0-3 newton between, respectively, 15 millimeters and zero millimeter distance. After three to four days, the rings cut through and disappeared from the anastomosis. Morphologic and microangiographic studies, undertaken at ten days, revealed that, in instances of good submucosal apposition, direct bridging of the defect in the submucosal layer was seen with rapid restoration of the villous epithelium and an undisturbed vascular pattern in the anastomotic area. This we called primary intestinal healing. In instances of bad submucosal apposition, we saw indirect bridging of the submucosal layer defect by smaller and longer strands of newly synthesized collagen tissue in the outer intestinal layers with a collateral circulation from the submucosal plexus to the arterial plexuses in these layers. In all instances, an epithelial defect still persisted at ten days. This type of wound healing we called secondary intestinal healing. The results showed that, with the magnetic rings, a significantly better apposition of the intestinal layers was achieved.

Animals↗
PubMed1980

[Increased success rate of renal transplantation by HLA-DR-typing: a retrospective analysis of the South-German co-operative study group for renal transplantation (author's transl)].

Retrospective HLA-DR-typing and the influence of HLA-DR antigen on transplantation prognosis was studied in 90 kidney donor-recipient pairs. It was clearly demonstrated that HLA-DR compatible donor kidney provides a significantly better transplant prognosis than if there is HLA-DR incompatibility. Donor kidneys with only one identical HLA-DR antigen gave a six-month survival rate of 80%. Only HLA-AB identical cadaver kidneys ("full house identity") give similar survival times. Because of relatively lower polymorphism of the HLA-DR alloantigen system, HLA-DR identical donor organs are discovered more frequently than when HLA-AB antigens are taken into consideration. HLA-DR identical donor kidneys (identical for both HLA-DR antigens) have an even better transplant prognosis than "full house identical" kidneys, since the survival rate in the former is 87% after six months.

HLA Antigens↗