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Biomedical subjects

R Linde

Publications and source records attributed to R Linde.

At least 55 records · Page 3Linked to original sources
PubMed1982

Dissociation of LH and FSH Responses to LHRH during estrogen therapy of patients with ovarian failure.

This study examines the effect of oral estrogen treatment on gonadotropin secretion in three young women with gonadal failure. Each subject was treated with 0.1 mg BID of ethinyl estradiol for four weeks, and the LH and FSH responses to 200 microgram of intravenously administered LHRH were measured basally and weekly during therapy. Significant reduction of basal levels of FSH occurred within one week of treatment, with obliteration of LHRH-mediated FSH responsiveness within two weeks. By contrast, basal levels of LH were significantly reduced by the end of the second week of treatment, and LHRH-mediated LH levels were sustained for three weeks. In one subject an LHRH test was performed every other day for two weeks after cessation of therapy. Return of FSH responsiveness was delayed one week beyond that of LH, which occurred within three days of discontinuation of estrogen. These results indicate that during the early phase of oral estrogen replacement therapy, FSH secretion may be selectively blunted; after discontinuation of treatment, recovery of FSH secretion lags behind recovery of LH.

Adult↗
PubMed1982

Comparable testosterone responses are produced by constant infusion of LH or GnRH in normal men.

Luteinizing hormone (LH) was infused continuously at a rate of 1.3 IU/min to 4 normal adult men. A 4 to 5-fold increase in serum LH was noted by 8 hours. Serum FSH declined steadily throughout the infusion period in the face of rising concentrations of gonadal steroids. Basal plasma testosterone of 4.7 +/- 0.4 ng/ml rose progressively to a peak of 11.1 +/- 0.9 ng/ml at hour 56 (p less than 0.005). A similar pattern was demonstrated by plasma androstenedione. Plasma 17 alpha-hydroxyprogesterone rose from a basal concentration of 0.81 +/- 0.14 ng/ml to a peak concentration of 2.6 +/- 0.3 ng/ml at hour 36 of the infusion and subsequently declined. A similar course was followed by serum estradiol-17 beta, which achieved a maximal concentration of 70.0 +/- 10.4 pg/ml at hour 36. Results are compared to those obtained with continuous infusion of GnRH in normal adult men. Testosterone responses were similar, whereas elevations in 17 alpha-hydroxyprogesterone and estradiol were higher following GnRH infusion. This difference may be consequent upon a direct gonadal effect of GnRH, or may be secondary to local regulation of testicular steroidogenesis by estradiol-17 beta.

Adult↗
PubMed1982

Intermittent long-term administration of a potent gonadotropin-releasing hormone agonist in normal men.

The effects on pituitary-gonadal function of the potent gonadotropin-releasing hormone agonist D-trp6-pro9-n-ethylamide-LHRH (LRFA), 50 micrograms subcutaneously every 4th day for 10 weeks, were evaluated in seven normal men. A modest rise in mean serum LH levels was noted during the treatment period. Mean serum FSH levels were unchanged. Mean plasma testosterone (T) levels remained at 3.1 ng/ml or above. Sperm density during the control period varied widely within and between subjects, with a mean range of 69-137 million/ml. The mean sperm density fell to a nadir of 40 million/ml during treatment, but no consistent pattern was observed for each subject, with values varying between 4 and 368 million/ml. Elevated LH and T values were observed on eight and seven occasions, respectively, in five subjects, and corresponded to blood samples drawn 24 and 48 h after the last LRFA injection. Depressed T values were observed on 10 occasions in six patients, and in all but one, corresponded to blood drawn 72 and 96 h after the last injection. One subject had daily blood samples drawn at the start of and 4 weeks after beginning therapy. An agonist effect on LH, FSH, T, and estradiol was observed both times, although the effect was blunted on the second occasion. We conclude that treatment every 4 day with LRFA does not appear to be a promising regimen to induce consistent suppression of the pituitary-gonadal axis in man.

Adult↗
PubMed1981

Reversible inhibition of testicular steroidogenesis and spermatogenesis by a potent gonadotropin-releasing hormone agonist in normal men: an approach toward the development of a male contraceptive.

We studied the antifertility effects of a potent gonadotropin-releasing hormone agonist, D-Trp6-Pro9-N-ethylamide-LHRH (LHRHA) in eight normal men, who received daily subcutaneous injections for six to 10 weeks. Plasma testosterone levels fell substantially in all eight. Plasma 17-hydroxyprogesterone and serum estradiol-17 beta levels decreased concordantly with plasma testosterone. Impotence developed in five men between the sixth and seventh weeks of treatment, with resolution in each case within two weeks of stopping treatment. Serum gonadotropin levels also fell during treatment, briefly rebounding above basal levels when therapy ended. Sperm density and motility fell t a nadir during the seventh to 18th week after therapy. In six subjects sperm levels fell to 6 X 10(6) sperm per milliliter or less, and in the other two they decreased 70 and 86 per cent below basal mean values. Sperm density returned to pretreatment levels in all men during the 10-to-14-week recovery period. These results are consistent with LHRHA-induced pituitary "desensitization" but do not exclude a direct inhibitory effect of LHRHA on testicular steroidogenesis and spermatogenesis.

Adult↗
PubMed1981

Graded dose effects of angiotensin II on aldosterone production in man during various levels of potassium intake.

This study was performed to evaluate the hypothesis that adrenal aldosterone output is modulated by daily potassium intake in man. Eight normotensive subjects, aged 24-38 yr, were fed 3 separate 150 mEq sodium-containing diets. Potassium content ranged from 300 mEq daily during the first week, to 80 mEq daily and 10 mEq daily for the subsequent 2 wk. On days 4 and 5 of each diet each subject took oral dexamethasone 0.5 mg B.I.D. to prevent endogenous ACTH secretion. On day 6 an infusion of angiotension II (AII) was administered in doses of 0.1, 0.3, 1.0, 3.0 and 10.0 ng/kg/min, each lasting 30 min. Blood pressure, pulse, and plasma aldosterone and potassium were measured throughout the infusions. All at infusion rates of 3 and 10 ng/kg/min, produced significant increases in plasma aldosterone values during liberal potassium intake but not when potassium intake was 10 mEq/day. We conclude that dietary potassium in man modulates All-mediated aldosterone secretion.

Adult↗
PubMed1980

Flashing tomosynthesis--a new tomographic method.

A new tomographic method called tomosynthesis and its first clinical results are presented. The method is based on classical tomography. All information necessary for the tomography of an object is obtained in one procedure without moving the X-ray tube, the film, or the object. Thus the investigation requires only a few seconds.

Humans↗
PubMed1979

Localization of aldosterone-producing adenoma by computed tomography.

Abdominal computed tomography (CT) was performed on nine patients with primary aldosteronism in an attempt to evaluate the utility of this noninvasive procedure in localizing aldosterone-producing adenomas. Confirmation of the diagnosis of primary aldosteronism was made by demonstrating elevated urinary aldosterone excretion, low PRA, and failure of plasma aldosterone to fall after acute saline load. Each patient had diagnostic lateralizing adrenal venous sampling and adrenal venography before unilateral adrenalectomy. The CT scan correctly predicted unilateral adenoma in the four patients whose tumors measured the largest in diameter at surgery. Bilateral tumors measuring 0.8 and 1.2 cm on scan (at or below the resolution capabilities of our scanner) were falsely predicted in two patients. The CT scan failed to identify an adrenal abnormality in three patients whose tumors measured 0.9, 1.0, and 1.0 cm in greatest diameter. It is concluded that at its current state of precision, the CT scan is of diagnostic utility in primary aldosteronism when a large adenoma is present. In our patients, the adrenal venogram and CT scan were equally accurate. The sampling of adrenal venous blood for aldosterone and cortisol remains the gold standard for localization of unilateral adenoma.

Adenoma↗
PubMedDate not supplied

Combined treatment with an LHRH agonist and testosterone in man. Reversible oligozoospermia without impotence.

We have previously shown that LHRH agonist [D-Trp6,Pro9-NEt]LHRH (LHRHA) results in reversible oligozoospermia when given to normal subjects for up to ten weeks. A fall in plasma testosterone was accompanied by loss of libido and potency. We now report six subjects who were evaluated by semen analysis and hormone profile at two-week intervals during ten-week basal, 20-week treatment, and post-treatment periods lasting at least ten weeks. Treatment consisted of LHRHA (50 microgram subcutaneously daily), and testosterone enanthate (100 mg intramuscularly every two weeks). Sperm density (mean basal 76.7 +/- 8.7 x 10(6)/ml) fell consistently in each subject to a mean nadir of 12.3 +/- 4.5 x 10(6)/ml (p less than 0.001). This is similar to the mean nadir of 11.6 +/- 5.8 x 10(6)/ml achieved when LHRHA was given alone. In each individual subject, sperm density returned to his basal level after cessation of treatment. No consistent changes were seen in sperm motility of morphology, or in semen volume. Libido and potency were maintained in all subjects. An additional three subjects received testosterone enanthate alone in identical dosage for 20 weeks. No change in sperm density was observed. In contrast to treatment with LHRHA alone, combination treatment produces reversible oligozoospermia without attendant change in potency.

Adult↗
PubMedDate not supplied

Real-time distortion correction of digital X-ray II/TV-systems: an application example for digital flashing tomosynthesis (DFTS).

In X-ray image intensifier (II)/TV-camera systems geometric distortions occur, e.g. due to the curved input screen of the II. For methods which are based on a pixelwise comparison of images, e.g. digital angio-tomosynthesis, an accurate correction of these geometric distortions is absolutely necessary. For the application of tomosynthesis to coronary angiography the correction in addition has to be done in real-time, because the reconstruction of the three dimensional structure of the blood vessels has to be done while the patient is undergoing catheterization. This paper describes a digital correction unit which allows a large variety of geometric distortions to be corrected. It consists of an input memory for storing the distorted image, an output memory for storing the corrected image and a special address memory which will serve as an address table during the correction step. For each element of the output image the location of the corresponding element of the distorted input image is determined in a preprocessing step and stored in the address memory. The actual correction of an image is then done while the image is copied from the input into the output memory. In this way 512 x 512 images can be corrected in real-time by a 32-bit 680X0-based microprocessor system. Presented as Poster at the 3rd International Symposium CAR '89 Computer Assisted Radiology, Berlin, June 25-28, 1989.

Coronary Angiography↗
PubMedDate not supplied

The CT detection of thymic hyperplasia in association with thyrotoxicosis: case report.

A thymic mass was diagnosed by computed tomography in a young male with an anterior mediastinal mass demonstrated by chest X-ray. The association of thymic hyperplasia and thyrotoxicosis is discussed and the importance of CT in the evaluation of anterior mediastinal masses in patients with thyrotoxicosis is emphasized. Micronodular enlargement of the thymus is a common association of Graves' disease in contradistinction to the rare detection of radiologically visible thymic masses in this condition.

Adolescent↗
PubMedDate not supplied

Hypophosphatemic rickets presenting as recurring pedal stress fractures in a middle-aged woman.

Stress fractures frequently occur from overtraining. When stress fractures recur, underlying metabolic abnormalities should be ruled out. We report a middle-aged woman in whom such an evaluation demonstrated previously undiagnosed hypophosphatemic rickets after she presented with recurring stress fractures in her feet. Treatment with phosphate and calcitriol was associated with clinical improvement that would likely not have occurred without this intervention. Any patient with recurring stress fractures should be evaluated with several screening laboratory tests, metabolic bone x-rays, and a measurement of bone mineral density.

Calcitriol↗
PubMedDate not supplied

[Nonparametric normal range for thrombocyte parameters in childhood].

In order to establish an univariate nonparametric pediatric tolerance region platelet function has been investigated in 105 healthy children and adolescents. In comparison to adult normal values, the bleeding time is shortened, spontaneous platelet aggregation is enhanced as well as collagen-induced platelet aggregation. 30% of the children showed an increased disaggregation in ADP-induced aggregation. A slight delay was found in the spreading of thrombocytes. Platelet volume shifted to the left. Values of beta-thromboglobulin were raised. Compared to adult values no alterations could be found in platelet shape-change. Changes of platelet functions were more apparent in the younger children.

Adenosine Diphosphate↗
PubMedDate not supplied

[Thrombolysis with rt-PA in children with arterial and venous thromboses--a new therapy concept].

Thrombolytic therapy usually used for thrombosis in the adult has been administered as a therapeutic regiment in pediatric patients (parental consent was sought prior to the treatment with rt-PA). We report our experience with rt-PA in 17 children and adolescents suffering from arterial (n = 4) or venous thrombosis (n = 13) due to local rhabdomyosarcoma, acute lymphoblastic leukemia, chronic myeloblastosis, sickle cell anaemia, parenteral nutrition, haemolytic uremic syndrome, central arterial and venous catheters and septicemia Thrombotic diseases have been diagnosed by Doppler ultrasound, computed tomography, angiography and phlebography. Rt-PA therapy was started immediately after diagnostic procedures had been performed. Rt-PA dose varied from 0.2 mg as a single dose to 0.8 mg/kg bw/d over a three day period in children local thrombolysis was performed. In patients requiring systemic thrombolytic therapy rt-PA was administered from 0.8 mg/kg bw/d in three days to 2.0 mg/kg bw/d over a whole period of three weeks in both groups during thrombolysis low dose heparin was added. When rt-PA infusion was terminated heparin (70 IU - 400 IU/kg bw/d) was administered for 7 to 14 days in order to prevent reocclusion. Later prophylaxis with coumarin derivatives in venous thrombosis and antiplatelet agents in arterial occlusive diseases was performed. In no patient did we see a decrease of fibrinogen and plasminogen during rt-PA therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗