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Biomedical subjects

P Kramer

Publications and source records attributed to P Kramer.

At least 109 records · Page 6Linked to original sources
PubMed1988

Effects of treatment with the opioid antagonists naloxone and naltrexone on LH secretion and on sexual maturation in immature female rats.

The effects on sexual maturation of the opioid receptor antagonists naloxone and naltrexone were studied in the female rat. Neonatal treatment (days 1-10) with either naloxone (2.5 mg/kg at 6-h intervals) or naltrexone (20 or 50 mg/kg per day) did not advance sexual maturation as judged by age and body weight at vaginal opening and first ovulation. After treatment with naltrexone (20 mg/kg) first ovulation occurred 2.3 days earlier than in saline-treated control rats but this could be attributed to a growth-stimulating effect of naltrexone; the effect was not observed with 50 mg/kg. An effect of neonatal treatment with naloxone on serum LH levels was seen at 23 days of age (155 +/- 36 (S.E.M.) vs 14 +/- 4 micrograms LH/l in controls, P less than 0.01), but not at 29 or 33 days of age, at 2 days before first ovulation nor at first pro-oestrus. There were no differences in the number of ova released at first oestrus, nor in the length of the first cycle. Neonatal treatment with naltrexone (50 mg/kg per day) did not alter the response to treatment with human chorionic gonadotrophin at 28-31 days of age: ovulation of a mean of 7.3 ova was induced on day 32 in both naltrexone- and saline-treated rats. Naltrexone treatment (four daily injections of 20 mg/kg at 2-h intervals) at 28-32 days of age advanced first ovulation by 4.4 days in about 40% of the rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Alport's syndrome as a cause of renal failure in Europe.

We studied the geographical distribution, male to female ratio, and age at the start of renal replacement therapy (RRT) for end-stage renal failure (ESRF) in 600 patients with hereditary nephritis with nerve deafness (Alport's syndrome) reported to the European Dialysis and Transplant Association Registry since 1975. Annual age- and sex-specific acceptance rates for RRT showed a variable peak incidence according to country, ranging between, 0 and 2.4 patients per million population in males aged 15-24 years, but with only about half this incidence in females. In Scandinavian countries there were very few females who started RRT, and males were older than in the rest of Europe. The overall male to female ratio was 4:1. The median age at the start of RRT was: males (n = 479) 24.3 years (1st quartile 19.5 years; 3rd quartile 31.5 years); females (n = 121) 31.5 years (1st quartile 23.0 years; 3rd quartile 43.2 years). Our study provided confirmation that males reach ESRF earlier than females. In addition, we detected previously unrecognized geographical differences.

Adolescent↗
PubMed1987

Trivalent influenza vaccine in patients on haemodialysis: impaired seroresponse with differences for A-H3N2 and A-H1N1 vaccine components.

One hundred and one patients on haemodialysis, 21 patients on peritoneal dialysis and 30 healthy controls received a trivalent split vaccine containing 15 micrograms haemagglutinin of a recent influenza A-H3N2, influenza A-H1N1 and influenza B strain, respectively. Antibody production after four weeks was determined by the haemagglutination-inhibition test and expressed as response rate, protection rate and overall mean fold increase. The patients on haemodialysis revealed a diminished seroresponse, as compared to patients on peritoneal dialysis and controls. For influenza A-H3N2, this was less distinct than for the other two antigens. In patients on haemodialysis the protection rate was 66% against the A-H3N2 vaccine component (versus 85% in controls, not significant), but only 25% against A-H1N1 and 27% against B (versus 84 and 77% in controls, p less than 0.001). Duration of haemodialysis up to eight years did not affect seroresponse. Patients on haemodialysis who were primed for influenza A-H1N1 in the period 1947-1957, reacted markedly better to the A-H1N1 vaccine component than subjects of other priming periods. A booster injection of the same vaccine dosage four weeks after the first immunization, performed in 98 patients on haemodialysis, was of little value: it had virtually no effect with regard to influenza A-H1N1 and influenza B, and showed, though significantly better, still poor results for A-H3N2. The differences in seroresponse between the A-H3N2 and A-H1N1 vaccine component suggest a major defect of primary, and a minor defect of secondary humoral response in patients on haemodialysis. The consequences for vaccine policy in these patients are discussed.

Adolescent↗
PubMed1987

Inhibition of first ovulation: administration of an LHRH antagonist to immature female rats.

Subcutaneous injections of an LHRH antagonist (ALHRH; Org.30093) were administered to immature female rats. Neither a single high dose (50 micrograms) nor repeated daily doses of 5-30 micrograms ALHRH/day, administered between 28 and 38 days of age, influenced the age and body weight at the time of vaginal opening or first ovulation. If repeated daily doses of 2 X 10 micrograms ALHRH were given from 32 to 42 or from 37 to 47 days of age, first ovulation was delayed by 3.0 and 6.3 days respectively. Administration of 10 micrograms ALHRH at 09.00 h and again at 17.00 h on the day of first pro-oestrus was found to be sufficient to block the expected first ovulation in 36 out of 38 rats. This effect could be repeated by administering the same doses of ALHRH at pro-oestrus and again on the next day: ovulation was blocked in eight out of eight rats. A single dose of 10 micrograms ALHRH, administered on the morning of pro-oestrus, blocked ovulation in five out of twelve rats. Both the preovulatory LH and FSH surge, as measured at 16.00 h on pro-oestrus, were found to be inhibited by ALHRH treatment. On the day after pro-oestrus no recruitment of new small antral follicles had occurred in rats with ovulatory blockade. Delayed ovulation took place 2-5 days after ALHRH injection at pro-oestrus; until 3 days after injection rats were able to ovulate their original preovulatory follicles, thereafter newly developed follicles ovulated and large ovarian cysts were found in the ovaries, next to fresh corpora lutea.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Effect of specific foods, beverages, and spices on amount of ileostomy output in human subjects.

To measure the effect of various selected foods on the amount of ileal excreta, 37 metabolic balance studies were performed on seven subjects who had normal functioning ileostomies for ulcerative colitis. Although this investigation was conducted with the subjects living at home and selecting their own diet, metabolic balance techniques were carefully observed. The diet was identical in the 3-day control and 3-day experimental period except for the alteration of one aspect of the diet in the experimental period. The substances tested were those often either interdicted for or avoided by ileostomates. Only seven (five fruits, one vegetable, and prune juice) of the 37 dietary substances significantly increased the ileal effluent. Excessive water intake, alcohol beverages, fried foods, and spices did not increase ileostomy output. A small but significant loss of sodium and in some instances potassium was observed with prune juice and some fruits that statistically increased ileal output. Although a limited number of foods were studied, application of the results suggests that many dietary substances generally avoided by or interdicted for ileostomates did not significantly increase the amount of ileal excreta when objective measurements are made.

Adult↗
PubMed1986

Periovulatory changes in serum concentration and ovarian content of 5 alpha-androstane-3 alpha, 17 beta-diol in the adult rat.

The high amounts of 5 alpha-androstane-3 alpha, 17 beta-diol (3 alpha-diol) present in immature female rats decline towards first ovulation, but on the day of first proestrus a peak is seen. This raises the possibility that during adulthood similar proestrous peaks may occur. Therefore, serum concentrations and ovarian content of 3 alpha-diol were estimated every two hours between 0900 and 2100 h in adult cyclic rats on the day of proestrus. In the same rats, serum concentrations of estradiol (E2), progesterone (P) and luteinizing hormone (LH) were measured, as were ovarian contents of E2 and P. A significant elevation in ovarian 3 alpha-diol was found between 0900 and 1700 h proestrus, whereas serum concentrations of 3 alpha-diol were elevated from 1300 to 2100 h. The high morning values of ovarian 3 alpha-diol correlated with those for ovarian E2 (p less than 0.005); the elevated serum concentrations of 3 alpha-diol during the afternoon correlated with serum P (p less than 0.005) and with serum LH concentrations (p less than 0.005). Serum and ovarian values were positively correlated for P and E2, but not for 3 alpha-diol. The rise in serum 3 alpha-diol could be prevented by blocking the LH surge with sodium pentobarbitone (Nembutal; 35 mg/kg b.w.) administered at 1300 h. In Nembutal-treated rats, the concentration of 3 alpha-diol at 1700 h (886 pg/ml) was significantly lower than in saline-treated control rats (1135 pg/ml; p less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1986

Shifts in perceived spatial frequency of low-contrast stimuli: data and theory.

We studied shifts in perceived spatial frequency of foveally viewed stimuli as a function of contrast, using lower contrasts and/or a lower range of spatial frequencies than used previously by others. Reliable shifts in perceived spatial frequency were found, but the direction of the shift at low frequencies was not the same as at high frequencies for some observers. Models based on either light scatter or an early compressive nonlinearity (transducer function) probably cannot account for these results. A multiple spatial-frequency-channels model in which a nonlinear contrast-transfer function (CTF) follows the output of each channel, however, is consistent with most of the results for suprathreshold contrasts. We considered several versions of this latter model, differing in their assumptions about the peak frequencies and bandwidths of the underlying channels, the shape of the CTF, and the combination rule by which the outputs of the channels are labeled and combined according to a weighted average.

Humans↗
PubMed1986

Inhibin increases in the ovaries of female rats approaching first ovulation: relationships with follicle growth and serum FSH concentrations.

In order to relate various prepubertal events in a group of 95 late prepubertal female rats, the following data were obtained during the last 10 days before the day of first ovulation: amounts of ovarian inhibin-like activity (ILA) in some animals (n = 47); size and numbers of healthy (antral) follicles with a volume greater than or equal to 100 X 10(5) microns3 (or diameter greater than or equal to 260 microns) present per ovary in their litter-mates (n = 48); serum FSH concentrations in both groups. Rats were unilaterally ovariectomized to obtain an ovary for either estimation of ILA content or for histological procedures and counting of follicles. At the time of unilateral ovariectomy they were bled to obtain serum for estimation of FSH concentrations. Rats were kept until the day after the day of first ovulation to determine the time-interval between the day of unilateral ovariectomy and first ovulation. They were studied between 10 and 1 days (days -10 to -1, maturational age) before first ovulation. In addition, adult cyclic rats were bilaterally ovariectomized on different days of the oestrous cycle for estimation of ovarian ILA content. The amount of ovarian ILA was estimated in steroid-free ovarian cytosols using an in-vitro bioassay system with dispersed anterior pituitary cells and subsequent measurement of FSH and LH in the spent medium. The amount of ovarian ILA was about 83 units/ovary from days -10 to -5, and subsequently increased (P less than 0.005) to reach a maximum on day -1, the day of pro-oestrus (213 units/ovary).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Persistent Epstein-Barr virus infection and a histiocytic sarcoma in a renal transplant recipient.

Lymphomas occurring in renal transplant recipients are mostly large cell non-Hodgkin's lymphomas (B-cell-derived). A sarcoma with all morphologic, immunohistochemical, and ultrastructural characteristics of a tumor of the mononuclear phagocytic system (MPS) developed in a 23-year-old woman 1 year after renal transplantation. Anti-Epstein-Barr-virus antibody titers proved to be exceptionally high, even in pretransplant sera. Tumor-derived cells proved to be positive for Epstein-Barr nuclear antigen (EBNA), and hybridization showed multiple copies of Epstein-Barr virus (EBV)-DNA, suggesting a relationship between this tumor and EBV. More widespread use of immunochemical and histochemical diagnostic techniques might detect more cases, which, until now, have probably been diagnosed as B-cell-derived immunoblastic lymphomas.

Adult↗
PubMed1985

[Use of low molecular-weight heparin in hemodialysis patients].

Low-molecular-weight (LMW) heparin has been compared to standard unfractionated (UF) heparin in a total of 49 patients on hemodialysis and hemofiltration in order to determine the necessary therapeutic dose and its effect on the coagulation system. A LMW heparin dose corresponding to 50% of the normal UF heparin dose was found to produce similar plasma heparin levels (anti-FXa-U/ml) in particular on minimal heparinization. At higher doses, UF heparin produced a more marked increase in plasma-heparin than did LMW heparin. Highly significant differences were found between UF and LMW heparin in their effects on PTT and thrombin time. Partial thromboplastin time (PTT) increased under UF heparin by an average of 120 s whereas LMW heparin only produced an increase of 5-7 s. Thrombin time was increased by 250-280 s under UF heparin and by 5-8 s under LMW heparin. With this LMW heparin dose of 50% of the UF heparin dose, no thrombosis of the extracorporal system occurred and no macroscopic detectable thrombotic material was found in the dialyzers or filters. No significant differences were observed between the effects of UF and LMW heparin on Factor VIII activity and fibrin monomers, so that a difference in coagulation activation between the two heparins can be excluded. Furthermore, there were no changes in thromboplastin time according to Quick, fibrinogen, antithrombin III, plasminogen, and a2-antiplasmin.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood↗
PubMed1985

Myocardial catecholamine balance during angina: effects of calcium entry blockers, verapamil and nifedipine.

To evaluate the effects of calcium entry blocking agents on cardiac sympathetic tone during angina pectoris, arterial and coronary sinus (CS) norepinephrine (NE) and epinephrine (E) concentrations and CS blood flow were determined at rest and during pacing-induced angina, both before and after verapamil in nine patients and after nifedipine in nine patients, all of whom had fixed obstructive coronary artery disease. Resting arterial NE and E concentrations and myocardial NE release and E uptake remained unchanged during angina before verapamil and nifedipine, suggesting unaltered systemic and cardiac sympathetic tone and myocardial E handling. Following verapamil and nifedipine, arterial NE and E concentrations remained unchanged. After verapamil, net myocardial NE release increased from 16,072 +/- 18,881 to 35,520 +/- 30,595 at preverapamil angina rate (p less than 0.01) and to 39,643 +/- 29,728 pg/min at postverapamil angina rate (p less than 0.01). NE release after nifedipine increased from -4207 +/- 8898 to 10,988 +/- 30,711 (p less than 0.05) at prenifedipine angina rate and to 19,942 +/- 26,644 pg/min (p less than 0.05) at postnifedipine angina rate. NE release was independent of changes in CS flow after verapamil or nifedipine. E uptake after verapamil and nifedipine remained unchanged. Although the precise mechanism is not known, myocardial alpha-adrenergic receptor blockage with verapamil and nifedipine remains a possible explanation for increased myocardial NE release.

Aged↗
PubMed1985

Effects of treatment with azathioprine and cyclosporin A on interferon-gamma production by peripheral blood leukocytes of renal allograft recipients.

We have studied the concanavalin A (ConA)-induced interferon gamma (IFN-gamma) production of peripheral blood mononuclear cells (PBMC) of renal allograft recipients. Both under immunosuppressive treatment with azathioprine and with cyclosporin A (CsA) the PBMC of these patients proved deficient for IFN-gamma production when compared to those of healthy controls. After conversion from conventional azathioprine to CsA medication the ConA-induced IFN-gamma production increased.

Azathioprine↗
PubMed1985

Changes in serum concentration and ovarian content of 5 alpha-androstane-3 alpha,17 beta-diol in the female rat approaching first ovulation.

Concentrations of 5 alpha-androstane-3 alpha,17 beta-diol (3 alpha-diol) in serum were estimated in rats bled once during a 10-day period preceding first ovulation; ovarian contents of 3 alpha-diol were estimated over the same period. Serum values of 3 alpha-diol, measured at 1100 h, showed a significant decrease towards first ovulation; there was good correlation (r = 0.78; n = 10) between mean serum and ovarian concentrations. In 33-day-old rats no significant difference was found in serum concentrations measured at either 1100 or at 1500 h. However at first proestrus, significantly elevated serum and ovarian concentrations of 3 alpha-diol were found between 1400 and 2100 h as compared to those at 1100 h. A similar pattern was seen on the afternoon of second proestrus. On the days following first ovulation, serum and ovarian concentrations of 3 alpha-diol were comparable to those during the days preceding this ovulation. The prepubertal decrease in 3 alpha-diol production is discussed in relation to concomitant changes in secretion of estradiol and luteinizing hormone. It is concluded that, in view of the preovulatory resynthesis of considerable amounts of 3 alpha-diol, it is inappropriate to view loss of biosynthetic capacity for 3 alpha-diol as a key event in the onset of puberty.

Androstane-3,17-diol↗
PubMed1985

Simultaneous measurement of spatial-frequency summation and uncertainty effects.

The predictions for summation and uncertainty effects from several multiple-spatial-frequency-channels models were calculated. The models differed in their assumptions about the shape of the channels' underlying probability-density functions and in the decision rule used to combine the channels' outputs. Varying these assumptions resulted in quite different predictions about the magnitudes of these effects. Simultaneous summation and uncertainty experiments measured the detectability of gratings containing one (simple) or two (compound) spatial frequencies. Performance was assessed in two types of blocks of trials: either each stimulus was in a separate block or three stimuli (two simple gratings and their compound) were randomly intermixed in one block. Quantitative comparisons of the models with the data showed that the increasing-variance Gaussian models (in which the decision variable is the sum of the monitored channels' outputs) provided the best overall fit.

Attention↗