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F Jockenhövel

Publications and source records attributed to F Jockenhövel.

64 records · Page 4Linked to original sources
PubMed1990

Varying dose-response characteristics of different immunoassays and an in-vitro bioassay for FSH are responsible for changing ratios of biologically active to immunologically active FSH.

Serum FSH levels in fertile and infertile men were determined by applying the Sertoli cell in-vitro bioassay and six different immunoassays. Bioassay and immunoassay estimates were significantly correlated (r ranging from 0.78 to 0.86; P less than 0.01). On average, all immunoassays measured lower FSH concentrations in samples with low FSH levels and higher FSH concentrations in those with high FSH levels compared with the bioassay. Ratios of bioactivity to immunoreactivity (B/I) were highest in fertile men and lowest in men with severe disturbances of testicular function. Depending on which immunoassay was used these differences were either significant or only marginal. Dose-response characteristics for WHO FSH standard preparation 78/549, used in the bioassay as well as in the immunoassays, were different between immunoassays and the bioassay, suggesting that decreasing B/I ratios with increasing FSH serum levels were method-related and reflected different slopes of the dose-response characteristics of the assays, rather than being true changes in the molecular composition of FSH. The present investigation underlines the necessity of choosing the immunoassay used for comparison with the bioassay carefully and of validating the system in regard to parallelism between dose-response characteristics. B/I ratios must be interpreted with great caution and previous studies which report changing B/I ratios in various endocrine situations may have to be reevaluated.

Biological Assay↗
PubMed1989

Diagnostic value of bioactive FSH in male infertility.

Bioactive FSH and immunoreactive FSH were determined in 193 infertile men and in 23 men with proven fertility using the Sertoli cell aromatase bioassay for bioactive FSH measurement and a two-site fluoroimmunoassay for immunoreactive FSH measurement. Overall bioactive and immunoreactive FSH levels correlated well (r = 0.74, p less than 0.001) but were significantly different from fertile men (bioactive FSH: 6.2 +/- 0.3 U/l; immunoreactive FSH: 4.1 +/- 0.4 U/l) in patients with Klinefelter's syndrome (24.1 +/- 6.1; 26.9 +/- 3.0), non-obstructive azoospermia (25.1 +/- 4.3; 22.2 +/- 4.0), maldescended testes (12.5 +/- 4.6; 14.6 +/- 1.6), and patients with severe oligozoospermia (11.9 +/- 1.2; 11.2 +/- 1.0). Infertile men with moderate oligozoospermia (8.9 +/- 1.5; 8.0 +/- 1.1) and normal sperm counts (9.6 +/- 1.1; 7.6 +/- 1.0) had insignificantly elevated bioactive FSH and immunoreactive FSH levels. Bioactive to immunoreactive FSH ratios were significantly reduced in all patient groups except for patients with normal sperm counts when compared with fertile men. A considerable number of patients exhibited elevated immunoreactive FSH concomitant with normal bioactive FSH levels. We conclude that 1. determination of immunoreactive FSH suffices for classification of patients; 2. bioactive to immunoreactive FSH ratios are reduced in infertile men; 3. some men might secrete immunoreactive FSH with reduced bioactivity.

Adult↗
PubMed1989

Circulating antibodies to monoclonal immunoglobulins used in a follitropin assay may cause incorrect fertility diagnosis.

We report grossly overestimated serum immunoreactive follitropin concentrations in an infertile man with normal spermatogenesis using a solid phase fluoroimmunoassay. The assay employs two monoclonal antibodies directed against two separate antigenic sites on the human follitropin molecule (DelFIA, Pharmacia). Determination of serum immunoreactive follitropin with a RIA based on polyclonal antiserum (WHO reagents), and of bioactive follitropin with the Sertoli-cell bioassay, revealed normal serum follitropin concentrations. Preincubation of the patient's sample with normal mouse serum or addition of normal mouse serum to the assay buffer neutralized the effect of the interfering substance in the DelFIA follitropin assay. Gel chromatography showed the interfering substance to have a relative molecular mass greater than 200,000. The substance is probably an antibody against mouse immunoglobulins, which cross-links the monoclonal mouse antibodies used in the DelFIA. The unknown incidence of heterophilic antibodies in human serum and the lack of preventive steps in some commercially available kits may lead, as in this case, to misdiagnosis in some patients.

Adult↗
PubMed1988

Hormonal effects of single gonadotropin-releasing hormone antagonist doses in men.

To assess its gonadotropin-inhibiting potency in man, three different doses of a GnRH antagonist [( Ac-D2-Nal1,D4-Cl-Phe2, D3-Pal3, Arg5,D4-p-methoxybenzoyl-2-amino butyric acid6,D-Ala10]GnRH; Nal-Glu GnRH antagonist) were given to six normal men. Single sc doses of 0.5, 1.5, and 5.0 mg Nal-Glu GnRH decreased mean serum immunoactive LH (iLH) to 45.0 +/- 5.7% (+/- SE), 37.0 +/- 4.9%, and 31.3 +/- 4.2% of baseline, respectively. Maximal suppression occurred between 4 and 8 h after drug injection. Serum bioassayable LH concentrations significantly diminished 8 h after injection of 1.5 and 5.0 mg GnRH antagonist, but not after the 0.5-mg dose. Mean serum testosterone (T) fell to 39.8 +/- 5.0%, 32.1 +/- 4.9%, and 20.7 +/- 4.4% of baseline, respectively, after the 0.5-, 1.5-, and 5.0-mg doses. The decreases in serum iLH and testosterone (T) were more sustained after the higher doses; serum iLH and T were significantly suppressed 24 h after administration of the 5.0-mg dose. Twenty-four-hour integrated serum iLH and T concentrations decreased in a dose-dependent manner. However, basal and 24-h integrated serum FSH concentrations were not significantly affected by the drug. No adverse systemic side-effects occurred. Thus, the Nal-Glu GnRH antagonist effectively decreases serum LH and T concentrations in a dose- and time-dependent manner, and it, therefore, has potential as a male contraceptive.

Adult↗
PubMed1986

Maintenance of complete but quantitatively reduced spermatogenesis in hypophysectomized monkeys by testosterone alone.

In order to investigate whether testosterone can maintain spermatogenesis in the absence of FSH in primates, four cynomolgus monkeys were hypophysectomized and implanted with 20 5-cm-long testosterone-filled silastic capsules within 45 min of pituitary ablation. Thereafter the serum levels of testosterone were elevated about 9-fold over presurgical levels. Testicular volumes declined to 60% of presurgical values. Testicular concentrations of testosterone were 50-180% of presurgical levels. Germ cell numbers were reduced to 30-50% of presurgical values and germ cell ratios suggested that the reduced numbers of all advanced germ cells were due to a decrease in the efficiency of proliferation of B spermatogonia. A fifth monkey was left untreated following hypophysectomy. Its serum testosterone was as low as that of castrated monkeys, and the testicular volume declined to 30% of that before surgery. Primitive spermatogonia were the only germ cells present 13 weeks after surgery. Thus, in primates testosterone alone maintains the complete process of spermatogenesis, however, spermatogonial proliferation is impaired in the absence of FSH.

Animals↗
PubMedDate not supplied

Lack of correlation between cadmium in seminal plasma and fertility status of nonexposed individuals and two cadmium-exposed patients.

Cadmium concentrations were determined in semen samples of 12 men with proven fertility (group I) and 44 normozoospermic patients (group II) as well as 118 unselected patients of an infertility clinic (group III) and 2 industrial workers with occupational exposure to cadmium. Mean cadmium concentrations in seminal plasma for groups I, II, and III did not show significant differences: 0.38 +/- 0.64; 0.43 +/- 0.69; 0.44 +/- 0.73 (mean +/- SD, micrograms/L), but the two cadmium-exposed patients revealed exceptionally high cadmium levels: 3.46 micrograms/L and 2.99 micrograms/L, respectively. There was no significant correlation between seminal cadmium concentrations and conventional semen parameters or between cadmium concentration and the fertility status of the patients. However, mean cadmium concentrations in seminal plasma of normozoospermic patients were higher in the group of smokers (0.55 +/- 0.81 micrograms/L), compared with the group of nonsmokers (0.42 +/- 0.67 micrograms/L), and there was a weak correlation between cadmium concentration and number of cigarettes consumed per day.

Adult↗
PubMedDate not supplied

Active immunization with relaxin does not influence objectively determined sperm motility characteristics in rabbits.

Two groups of 5 rabbits were actively immunized with porcine relaxin or sham immunized. Serial analysis of sperm motion characteristics using the computer assisted Hamilton-Thorn Motility Analyzer over a period of 22 weeks did not reveal any significant antibody titers in serum and seminal plasma. In consideration of the present findings and after critical review of the literature it is concluded that an influence of relaxin on sperm motility is unlikely.

Animals↗
PubMedDate not supplied

The influence of relaxin on motility of human sperm in vitro.

Sperm of healthy men were incubated in an IVF medium with relaxin at concentrations of 3, 30, 300 and 3000 ng ml-1. Immediately after addition of relaxin and 60 and 120 min later motility, progressive motility, mean path velocity, mean progressive velocity, mean linearity and mean lateral head displacement were measured with the Hamilton-Thorn motility analyser. Neither immediately after relaxin addition, nor after 60 or 120 min, was an improvement of sperm motility observed at any concentration.

Culture Media↗
PubMedDate not supplied

Seminal lead and copper in fertile and infertile men.

Lead and copper concentrations were determined by atomic absorption spectroscopy in semen from 18 fertile and 172 infertile men. Significant correlations between copper concentrations in semen and sperm concentration (r = 0.32, P less than 0.001), percentage progressive motility (r = 0.23, P less than 0.005) and normal morphology (r = 0.22, P less than 0.005) were observed, while no such correlation existed for lead. However, semen copper concentrations of infertile men (194.99 +/- 5.70 micrograms l-1) and fertile men (183.39 +/- 14.37 micrograms l-1) did not differ significantly. Mean lead concentration in semen of fertile men was 11.18 +/- 0.62 micrograms l-1 and significantly higher than lead concentration in semen of fertile men (5.61 +/- 0.53 micrograms l-1, P less than 0.006). Reinvestigation of 18 infertile men after 2 years showed a significant drop of lead concentrations in semen from 17.31 +/- 1.41 to 6.94 +/- 1.32 micrograms l-1 (P less than 0.0002), which might be related to the decreasing use of leaded petrol in the Federal Republic of Germany.

Copper↗