Biomedical subjects

G U Exner

Publications and source records attributed to G U Exner.

At least 73 records · Page 4Linked to original sources

PubMed1984

Idiopathic osteoporosis in a three-year-old girl. Follow-up over a period of 6 years by computed tomography bone densitometry (CT).

In a girl suffering from idiopathic transient osteoporosis the development of vertebral deformation and recovery could be followed from the age of 3.4 to 9.3 years. Computed bone densitometry (CT) revealed values below normal for trabecular bone density (-2.6 SD at 4.3 years and -2.8 SD at 5.3 years) during the clinically symptomatic phase of the disease and normalization after the age of 6 years (-0.2 SD at 6.7 and 9.3 years). Cortical bone mineral parameters measured by CT and metacarpal bone measurements from conventional X-rays showed values at the lower range of normal and only a weak correlation with clinical symptoms, vertebral deformation and recovery, respectively. CT may probably allow to diagnose osteoporosis before the appearance of deformities or fractures; in milder forms of osteoporosis the diagnosis may be possible by CT only.

Bone Development↗

PubMed1982

Transient impairment or delay of urinary trihydroxypregnanone (THS) response to metyrapone in boys with delayed adolescence and in patients with isolated growth hormone deficiency.

Twenty three boys with delayed adolescence (age 15.7 +/- 2.0, bone age 12.4 +/- 2.1 years) were studied. Their cortisol response to insulin was normal. After oral metyrapone (500 mg/m2 by mouth) one to three consecutive 12 h urine samples were collected for analysis of THS. Thirty seven tests with 37 first, 21 second, and 11 third samples were carried out. The results could be divided into two main groups: 25 tests (group A) were subnormal in the first sample, 12 of them with a very weak (40 +/- 8 micrograms/m2/12 h) and 13 with an insufficient (191 +/- 16 micrograms/m2/12 h) THS response. Values in the second and third sample were higher, indicating a delayed response. In 12 tests (group B), the results were normal (1016 +/- 143 micrograms/M2/12 h) in the first and lower in the second and third samples. In three patients with repeated tests, there was improvement with increasing bone age. The THS-responses to metyrapone did not correlate with those of growth hormone, gonadotrophins, and TSH to stimuli. It is concluded that the THS-response to a single dose of metyrapone may be temporarily insufficient or delayed in delayed adolescence. We interpret this finding as showing transiently reduced or slow hypothalamic responsiveness.

17-Hydroxycorticosteroids↗

PubMed1980

Effects of high dose oestrogen and testosterone treatment in adolescents upon trabecular and compact bone measured by 125I computed tomography. A preliminary study.

125I Computed Tomography (CT) allows for the selective determination of trabecular and compact bone mineral parameters in the radius. Using this technique the effects of high dose oestrogen treatment in 11 tall girls, and of high dose testosterone treatment in 5 tall boys were monitored. In both groups trabecular bone density (TBD) increased steadily during treatment at a rate of about 1% per month. Also in both groups the compact bone mineral increased steadily. These results are compared with those from a cross sectional study on 49 normal children and 36 normal adults, in whom TBD was found to be independent of age and sex, so that the increases in TBD in both treatment groups can be attributed directly to the influence of the sex hormones. Since the compact bone mineral is higher in adults than in children it cannot yet be decided whether the increases seen in the treated patients are related to the sex hormone treatment, or reflect only the normal development of the bone during adolescence.

Adolescent↗

PubMed1980

Hypophosphatemic vitamin D resistant rickets (phosphate diabetes): bone mineral problems studied by 125I-computed tomography and microradiography.

125I-computed tomography (CT) for the bone mineral analysis of the radius was performed on 9 children with vitamin D resistant hypophosphatemic rickets (VDRR) treated with vitamin D in pharmacological doses. Trabecular bone density was increased in 1 patient and normal in all others. The cortical width of the diaphysis of the radius was decreased, and the cross sectional area of the bone increased, but the total amount of compat bone mineral in the cross section was normal. Measurements of the second metacarpal bone on X-rays of the hand revealed similar findings. Microradiographic and histological examinations of the fibula on 9 different patients also treated with vitamin D showed grossly abnormal mineralization of bone tissue with a perilacunar mineral deficit. It is concluded, that the amount of compact bone and trabecular bone is not decreased in children with VDRR. The normal mineral content determined by CT and the impaired mineralization of the bone material examined by microradiography indicate an over-abundance of incompletely mineralized bone.

Adolescent↗

PubMed1979

Loss and recovery of trabecular bone in the distal radius following fracture--immobilization of the upper limb in children.

Computed tomography of the human radius is performed using a special purpose scanning device which incorporates a radionuclide (125I) as radiation source. Parameters decribing the trabecular bone and the compact bone are determined at a distal and a diaphyseal measuring site respectively. Using this measurement technique changes in bone mineralization in the radius were studied in a group of 23 children following immobilization of an upper limb for fracture healing. An immobilization period of between three to six weeks resulted in a reduction of the relevant parameter value of up to 44% (mean 16%) in the distal part of the radius, whereas no significant change could be seen in the diaphyseal part of the same bone. Rapid remineralization of trabecular bone is indicated by the increase of the corresponding parameter value at a rate of up to several percent per week. However, in some of the patients studied complete normalization was not attained during the first six months following cast removal.

Bone Regeneration↗

PubMed1979

Bone densitometry using computed tomography. Part I: selective determination of trabecular bone density and other bone mineral parameters. Normal values in children and adults.

Gamma-ray computed tomography (gamma-ray CT), using a special purpose scanner, enables in-vivo quantitative analysis of bone mineralization. Trabecular bone density (TBD), the relative amount of compact bone (bone density, BD) and the total absorption (TA) for a cross-section of the radius are determined from measurements of local linear absorption coefficients. A preliminary study of normal children (n = 49) and adults (n = 34) indicated that TBD is independent of age and sex in the age range 4 to 40 years. DB remains constant throughout childhood but increases after puberty in both women and men. TA is higher for adults than for children, and also higher for men than for women. A correlation between TA and parameters relating to body size indicates a relationship between body weight and bone mass.

Adolescent↗

PubMed1979

Bone densitometry using computed tomography. Part II: increased trabecular bone density in children with chronic renal failure.

The method of gamma-ray computed tomography (gamma-ray CT) bone densitometry described in the preceding article provides selective determination of trabecular bone density (TBD), the relative amount of compact bone (bone density, BD), and the total absorption (TA) within a bone cross section. Seven of nine children with chronic renal failure (CRF), and selected only on the basis of their serum creatinine value (greater than 5 mg/100 ml), had increased TBD values above the normal range, whereas the other bone mineral parameters were normal. Radiographic signs of secondary hyperparathyroidism (subperiosteal erosions, cysts) were reported in the five patients with the highest TBD values, whereas the subjective diagnosis of osteosclerosis reported in three of these five and in one other patient correlated less well with the TBD increases. However, this is the first report of an objective, non-invasive documentation of the radiological finding of osteosclerosis in CRF. It also explains why methods for bone mineral measurements used previously, such as a photon absorptiometry which provides only a parameter equivalent to TA, failed to reveal increases in bone mineral content in renal osteodystrophy even when signs of osteosclerosis were present. Thus, gamma-ray CT helps to document objectively the degree of osteosclerosis and its location.

Adolescent↗

PubMed1978

Growth retardation and bone mineral status in children with coeliac disease recognized after the age of 3 years.

Growth data, clinical symptoms and bone mineral parameters were analyzed in 20 children with coeliac disease in whom the diagnosis was established by biopsy at age 3-13 years. Small stature and bone age retardation (greater than 2 SD) were present in 65% and 60%, respectively. Typical clinical symptoms of coeliac disease as found in the younger child were present in many cases, but 3 were completely asymptomatic except for severe growth retardation. Metacarpal diameters and cortical thickness were significantly decreased for chronological age but in most cases normal for bone age. Quantitative bone mineral analysis of the radius by computed tomography revealed normal values for height and weight in the 4 cases investigated. It is concluded that coeliac disease should always be considered in the differential diagnosis of retarded growth and bone age. "Osteoporosis" may occur in coeliac disease, but does not necessarily accompany growth failure. The analysis of metacarpal diameters and cortical thickness in the search of "osteoporosis" may result in false interpretation if not correlated to height and weight.

Adolescent↗

PubMed1977

Treatment of cryptorchidism by intranasal synthetic luteinising-hormone releasing hormone. Results of a collaborative double-blind study.

The effect of intranasal luteinising-hormone releasing hormone (L.H.R.H.) in 84 boys with unilateral or bilateral cryptorchidism was evaluated in a double-blind controlled trial. Boys with retractile testes were not studied. L.H.R.H. caused no side-effects; plasma antibodies to L.H.R.H. were never demonstrated. Four weeks' therapy with intranasal L.H.R.H. administered in six doses daily (1.2 mg/day) led to complete descent in 38% of a total of 61 testes, an improved position in 28%, and no response in 19%; 15% of testes were never palpated. After placebo the position of 25% of testes was improved; there was no response in 75% of a total of 51 testes. The success-rate seemed to be independent of age, but was related to the initial testicular position, with complete descent in only 11% of testes not previously palpated compared with 48% of testes found in the inguinal region.

Administration, Intranasal↗

PubMed1975

Influence of intermittent long-term stimulation on contractile, histochemical and metabolic properties of fibre populations in fast and slow rabbit muscles.

Slow (m.soleus) and fast (m.tibialis anterior) muscles of the rabbit were subjected to indirect long-term intermittent stimulation (3 weeks, 8 hrs daily) with a frequency pattern of 10 imp/sec. Whereas no changes were observed in case of the slow muscle, stimulation induced profound changes in the fast tibialis anterior muscle. These consisted in a rearrangement of the enzyme activity pattern of energy-supplying metabolism, e.g. decrease in glycogenolytic and glycolytic enzyme activities and severalfold increase in key enzymes of aerobic endoxidation of substrates in beta-oxidation and the citric acid cycle. Concomitant with the increase in aerobic oxidative capacity, there was an increased resistance to fatigue. Histochemical studies revealed a strong increase in mitochondria of all fibres. The bimodal distribution of fibre cross-sectional area in the normal tibialis anterior muscle was changed by stimulation into a more homogeneous population of fibres with a smaller cross-sectional area. Despite a 50% increase in time to peak of isometric twitch contraction no changes were observed in the fibre population with regard to myofibrillar ATPase reaction in quantitative evaluation of whole cross-sections of the muscles. The percentage of fibres histochemically classified as slow amounted to 2.8% and 3.1% in control and stimulated tibialis anterior muscle. Nevertheless the data suggest a transformation of the fibre population under the influence of long-term intermittent stimulation.

Adenosine Triphosphatases↗

PubMed1974