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Biomedical subjects

W Kern

Publications and source records attributed to W Kern.

At least 127 records · Page 7Linked to original sources
PubMed1993

Corticotropin-releasing hormone-induced adrenocorticotropin and cortisol secretion depends on sleep and wakefulness.

Twenty-four-hour profiles of pituitary-adrenocortical secretory activity in humans are characterized by a distinct decrease in hormone secretion after sleep onset and a strong increase during the early morning hours. It is a widely accepted notion that this pattern of hormone secretion is driven by intrinsic circadian oscillators, and the contributions of sleep and wakefulness have been greatly neglected. Here, we examined whether there is a sleep-dependent inhibition of stimulated ACTH and cortisol release during early nocturnal sleep, which is dominated by slow wave sleep (SWS). We administered human CRH (hCRH; 50 micrograms), the main corticotropin secretagogue, to 14 healthy men during the first SWS period after sleep onset and another time in the same night during a period of stage 2 sleep in the second half of sleeping time. To discriminate possible circadian influences from influences of sleep, on a second night another two injections of hCRH were administered at identical points during the night to the same subject, who was kept awake. Exclusively during sleep, but only during SWS in the beginning of sleep time, ACTH and cortisol responses to hCRH were blunted. The results demonstrate an inhibiting influence of sleep on stimulated ACTH and cortisol secretion, with this effect restricted to the early part of sleep.

Adrenocorticotropic Hormone↗
PubMed1992

[Lemierre's syndrome with splenic abscesses].

A week after onset of a pharyngo-tonsillitis a previously healthy 23-year-old man developed high fever (41.4 degrees C), leukocytosis (12,200/microliters) with marked shift to the left, thrombocytopenia (86,000/microliters) and increased transaminases (GOT 83 U/l, GPT 113 U/l). Chest x-ray film suggested intrapulmonary abscesses with left-sided pleural effusion. The suspected diagnosis of "post-tonsillitis" septicaemia (Lemierre's syndrome) was confirmed by demonstrating anaerobic, fusiform, gram-negative bacteria (Fusobacterium nucleatum and necrophorum) in several blood cultures. Despite antibacterial treatment (amoxicillin/clavulanic acid, imipenem/cilastatin, clindamycin) he had recurrent pain referred to the kidney region and persisting fever. Repeated ultrasound and radiological examinations revealed new foci in the spleen, which were enlarging. Laparotomy with splenectomy performed on day 17 after the begin of treatment confirmed multiple splenic abscesses, but abscess pus and splenic tissue were sterile. After altogether 6 weeks of antibiotic treatment, finally with chloramphenicol, the patient was discharged in a good general state.

Abscess↗
PubMed1992

[Malaria tropica].

Explore the source record for details and available documents.

Exchange Transfusion, Whole Blood↗
PubMed1992

Vasopressin regulates human sleep by reducing rapid-eye-movement sleep.

In two double-blind experiments, effects of intravenous infusion of arginine vasopressin (AVP) on sleep were evaluated in 2 groups of 10 men (20-35 yr). In experiment I, subjects were tested on two occasions, during which they received either placebo or 0.33 IU/h AVP. In experiment II, on three different occasions, subjects received either placebo or 0.66 or 0.99 IU/h AVP. Infusions were administered between 2200 and 0700 h. Nocturnal plasma AVP concentrations were close to the upper limit of the normal physiological range during 0.66 IU/h AVP (16.6 +/- 2.2 pg/ml) but markedly exceeded this range during 0.99 IU/h AVP (25.0 +/- 1.6 pg/ml). Results indicate primary effects of AVP on rapid-eye-movement (REM) sleep, with moderate reductions in REM sleep during 0.33 IU/h AVP (averaging -10.5%) and with substantial reductions in REM sleep (-24.0%) during 0.66 IU/h AVP. During 0.99 IU/h AVP the effect did not further increase (-24.4%). Less consistent effects of AVP were an increase in stage 2 sleep and in time awake. Effects of AVP were not mediated by changes in cortisol or blood pressure. Results suggest AVP to participate in REM sleep regulation under normal physiological conditions.

Adult↗
PubMed1992

Nocturnal adrenocorticotropin and cortisol secretion depends on sleep duration and decreases in association with spontaneous awakening in the morning.

It is still discussed controversially to what extent the nocturnal activity of the hypothalamus-pituitary-adrenocortical system depends on sleep and awakening in the morning. Therefore, we investigated the association of plasma ACTH and cortisol levels with undisturbed nocturnal sleep and spontaneous awakening in 14 healthy male subjects (between 2300 h and 1100 h). Between sleep onset and 476.9 min after sleep onset mean plasma cortisol level was significantly (P < 0.01) higher (210 +/- 15 vs. 155 +/- 9 nmol/L) in the group with a shorter (476.9 +/- 15.0 min; n = 7; mean +/- SEM) than in the group with a longer total sleep time (596.9 +/- 14.4 min; n = 7). Spontaneous awakening in the morning was not linked to the presence of any specific sleep stage or to rising plasma ACTH and cortisol levels. However, spontaneous awakening was followed by a brief rise in plasma ACTH and cortisol in both groups. Thereafter, during wakefulness plasma ACTH and cortisol abruptly declined in all subjects irrespective of the time of awakening. The slope of the plasma ACTH and cortisol curves differed significantly (ACTH: P < 0.001; cortisol: P < 0.002, for all subjects) comparing the time after awakening (until 1100 h) with a time interval of identical length before awakening. We conclude that the duration of sleep and nocturnal ACTH and cortisol secretion are interrelated. Furthermore, the data suggest that the endogenous early morning activation of the hypothalamus-pituitary-adrenocortical system is terminated by mechanisms closely associated with awakening.

Adrenocorticotropic Hormone↗
PubMed1991

Sleep disruption alters nocturnal ACTH and cortisol secretory patterns.

Recent studies have provided evidence that nocturnal cortisol secretion is coupled to ultradian rhythms of sleep. The present study was designed to specify how exogenous and sleep-related endogenous factors influence nocturnal adrenocorticotropin (ACTH) and cortisol secretion. We compared the influences of (1) temporary sleep deprivation, (2) arousals continuously induced during sleep and, (3) undisturbed sleep (baseline) on pituitary-adrenocortical activity in 10 healthy men. Sleep deprivation (DS) and continuous arousals during sleep (AS) were introduced at the beginning of the second rapid eye movement (REM) sleep period which is an epoch close to the first significant nocturnal rise in plasma cortisol. Compared with the baseline nights, plasma cortisol significantly increased immediately after continuous arousals were started or the subject was awakened and remained awake. Despite this exogenously provoked first cortisol peak, average cortisol release during DS and AS was no higher than during undisturbed sleep. The arousal-induced cortisol burst was followed by a temporary inhibition of cortisol secretion, suggesting that once the subject is aroused (i.e., in stage 1 sleep or awake), the hypothalamus-pituitary-adrenal (HPA) system becomes highly sensitive to negative feedback inhibition. Spontaneously occurring endogenous cortisol peaks of comparable size during undisturbed sleep did not exhibit such a temporary inhibition of cortisol secretion. We hypothesize that sleep attenuates negative feedback inhibition within the HPA system, whereas wakefulness (or stage 1 sleep) reflects increased feedback sensitivity of this system.

Adrenocorticotropic Hormone↗
PubMed1991

The role of adjuvant chemotherapy following cystectomy for invasive bladder cancer: a prospective comparative trial.

We assigned 91 patients with deeply invasive, pathological stage P3, P4 or N+ and Mo transitional cell carcinoma of the bladder (with or without squamous or glandular differentiation) to adjuvant chemotherapy or to observation after radical cystectomy and pelvic lymph node dissection. For most patients chemotherapy was planned as 4 courses at 28-day intervals of 100 mg./M.2 cisplatin, 60 mg./M.2 doxorubicin and 600 mg./M.2 cyclophosphamide. A significant delay was shown in the time to progression (p = 0.0010) with 70% of the patients assigned to chemotherapy free of disease at 3 years compared to 46% in the observation group. Median survival time for patients in the chemotherapy group was 4.3 years compared to 2.4 years in the observation group (p = 0.0062). In addition to treatment groups, important prognostic factors included age, gender and lymph node status. The number of involved lymph nodes was the single most important variable. We recommend adjuvant chemotherapy for patients with invasive transitional cell carcinoma after definitive surgical resection.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1991

Removal of the antibacterial activity of trimethoprim-sulfamethoxazole, ofloxacin and zidovudine by BACTEC resin-containing blood culture medium.

We determined the capacity of BACTEC resin blood culture media NR 16A and NR 17A to remove the antibacterial activity of trimethoprim-sulfamethoxazole, ofloxacin and zidovudine. Simulated blood cultures containing increasing antibiotic concentrations were inoculated with 10(1), 10(3) and 10(5) CFU/ml blood of various bacterial strains and evaluated with the BACTEC infrared growth detection system. The antibiotic concentrations were adjusted to give breakpoint concentration in the added serum volume or in the total volume of the blood culture vials. Recovery rates and time until detection of bacterial growth in resin-media were compared with those in resin-free media. Trimethoprim-sulfamethoxazole and ofloxacin were, similar to piperacillin, inactivated by resins at antibiotic concentrations that were up to ten times higher than those easily achievable in serum. The antimicrobial effect of zidovudine on gram negative bacteria was reduced in resin media at concentrations corresponding to fifteen times the peak serum levels. Growth of P. aeruginosa, but not of S. aureus, E. coli, K. pneumoniae and Salmonella, was delayed in the presence of resins even at subinhibitory antibiotic concentrations when compared with resin-free media.

Bacteremia↗
PubMed1991

Gluco- and antimineralocorticoid effects on human sleep: a role of central corticosteroid receptors.

Cortisol modulates brain functions in humans. This principal endogenous glucocorticoid in humans decreases rapid-eye-movement (REM) sleep and increases slow-wave sleep (SWS). Because cortisol exerts its effect on brain functions via mineralocorticoid receptors (MR) and glucocorticoid receptors (GR), we were interested in which type of corticosteroid receptor mediates these steroid effects on sleep. Healthy men were tested in two double-blind experiments. In experiment I (n = 8), the subject's sleep was tested during four nights: 1) after pretreatment with dexamethasone (Dex, 4 mg/day) for 4 or 6 days and after additional infusion of placebo or cortisol (10 mg/h) during the experimental night, 2) after pretreatment with placebo for 4 or 6 days and after infusion of placebo or cortisol (10 mg/h) during the experimental night. In experiment II, subjects (n = 10) slept after intravenous administration of potassium canrenoate (200 mg, at 0800 and 1700 h before experimental nights) or placebo. Cortisol infusion moderately increased the percentage of SWS (P less than 0.05) and markedly decreased REM sleep (P less than 0.01); influence of cortisol on SWS did not depend on pretreatment with Dex. Dex reduced both SWS and REM sleep (P less than 0.05). Canrenoate markedly diminished SWS (P less than 0.01) but left REM sleep unaffected. The results suggest that corticosteroid-induced changes in SWS are mediated via MR-like central receptors in humans, whereas changes in REM sleep involve GR.

Adult↗
PubMed1991

Sleep-associated augmentation and synchronization of luteinizing hormone pulses in adult men.

We reinvestigated the temporal relationship between sleep and LH secretion in healthy adult males by comparing LH secretion patterns during sleep with those during the 6 h of wakefulness preceding the sleep epoch. Sleep stages were determined by somnopolygraphy. In these subjects LH secretion was augmented during sleep as indicated by increased mean LH concentrations and increased pulse amplitudes; pulse frequency was not different. In addition, LH secretion appeared to be synchronized to the NonREM-REM sleep cycles: initiation of LH pulses occurred preferentially in the mid-portion of a NonREM-REM cycle during Non-REM sleep. Thus, REM sleep was almost uniformly associated with decreasing LH concentration. These findings demonstrate that patterns of LH secretion characteristic for early puberty are principally present also in adult males.

Adult↗
PubMed1991

Neuropsychiatric side effects after the use of mefloquine.

This study describes neuropsychiatric side effects in patients after treatment with mefloquine. Reactions consisted mainly of seizures, acute psychoses, anxiety neurosis, and major disturbances of sleep-wake rhythm. Side effects occurred after both therapeutic and prophylactic intake and were graded from moderate to severe. In a risk analysis of neuropsychiatric side effects in Germany, it is estimated that one of 8,000 mefloquine users suffers from such reactions. The incidence calculation revealed that one of 215 therapeutic users had reactions, compared with one of 13,000 in the prophylaxis group, making the risk of neuropsychiatric reactions after mefloquine treatment 60 times higher than after prophylaxis. Therefore, certain limitations for malaria prophylaxis and treatment with mefloquine are recommended.

Adult↗
PubMed1990

Prevention of infection in acute leukemia.

In a randomized study comparing cotrimoxazole plus colistin with ciprofloxacin, each in combination with nonabsorbable antimycotics, the incidence of major infections in terms of septicemias and pneumonias as well as of minor infections and episodes of unexplained fever (FUO) was higher in patients treated with ciprofloxacin. In cases of microbiologically documented infections, gram-positive cocci dominated by far. In surveillance cultures of oral washings and of feces, gram-negative enterobacteria were only rarely detected; however, large numbers of cultures were positive for Acinetobacter species. There were four cases of documented Pneumocystis carinii pneumonia in patients not receiving cotrimoxazole. The incidence of documented mycotic infections as well as the detection of fungi in surveillance cultures was similar in both treatment groups. A decrease in the number of adverse events, especially of allergic reactions, could not be achieved by the administration of ciprofloxacin. In conclusion, cotrimoxazole plus colistin in combination with nonabsorbable antimycotics remains the standard regimen for prevention of infection in patients with acute leukemia undergoing aggressive remission induction therapy. A detailed analysis of study II will be prepared for publication.

Acute Disease↗
PubMed1990

Molecular epidemiological study of Pseudomonas aeruginosa isolates from patients with acute leukemia.

In an attempt to determine the genetic relationship between strains of Pseudomonas aeruginosa isolated from patients with acute leukemia, a recently described restriction fragment from the region upstream of the exotoxin A structural gene was used as a probe in Southern hybridization. The overall rate of cultures positive for Pseudomonas aeruginosa during 169 admissions (119 patients) was 17%. Twelve genotypically distinct strains were found among 18 colonized and/or infected individuals. Three of these strains were recovered from more than one patient, suggesting a certain risk of nosocomial transmission of Pseudomonas aeruginosa and cross-infection. Genotypic comparison showed identical restriction patterns in multiple isolates from single patients, and also in colonizing and subsequently infecting strains. Genotyping distinguished isolates with similar O serotypes and established the identity between isolates with differing susceptibility to agents used for antibacterial prophylaxis.

Acute Disease↗