A histomorphological study in age related changes in the elastic fiber system of the basilar artery

The aim of the study was to quantify the distribution of elastic fibers within the wall of the basilar artery. Three age groups were studied: 1) 0-1 yr.; 2) 20-50 yr. 3) > 50 yr. A histomorphometrical study was undertaken using an estimation of the linear density of the components of the fibrous elastic tissue system: the full length in the proximal and distal segments of the basilar artery was evaluated. Our results showed that: The elastic tissue of the basilar artery is not evenly distributed throughout the tunica media. Compared to the 0 to 1-year age group, mature elastic, elauninic and oxytalan fibers decreased with age. In all age groups the linear density of the mature elastic fibers was more evident in the proximal than in the distal segment of the artery.     

Increased incidence of congenital malformations in children with transient thyroid-stimulating hormone elevation on neonatal screening

Huntington's disease is an autosomal-dominant inherited progressive neurodegenerative disease associated with an expanded trinucleotide repeat (CAG) sequence on the short arm of chromosome 4. The disease is considered rare in Africans. We report five black South African families of different ethnic origin with proven expansions typical of Huntington's disease and discuss the possible origins of the disease in Africa.     

Fourier transform Raman spectroscopy of polyacrylamide gels (PAGs) for radiation dosimetry

Polyacrylamide gels (PAGs) are used for magnetic resonance imaging radiation dosimetry. Fourier transform (FT) Raman spectroscopy studies were undertaken to investigate cross-linking changes during the copolymerization of polyacrylamide gels in the spectral range of 200-3500 cm(-1). Vibrational bands of 1285 cm(-1) and 1256 cm(-1) were assigned to acrylamide and bis-acrylamide single CH2 deltaCH2 binding modes. Bands were found to decrease in amplitude with increasing absorbed radiation dose as a result of copolymerization. Principal component regression was performed on FT-Raman spectra of PAG samples irradiated to 50 Gy. Two components were found to be sufficient to account for 98.7% of the variance in the data. Cross validation was used to establish the absorbed radiation dose of an unknown PAG sample from the FT-Raman spectra. The calculated correlation coefficient between measured and predictive samples was 0.997 with a standard error of estimate of 0.976 and a standard error of prediction of 1.140. Results demonstrate the potential of FT-Raman spectroscopy for ionizing radiation dosimetry using polyacrylamide gels.     

Spontaneous intracranial hypotension: report of four cases and review of the literature

Spontaneous intracranial hypotension is an unusual syndrome of postural headache and low cerebrospinal fluid pressure without an established cause. We present four cases, analyze those previously reported in the literature, examine the MRI, CT, angiographic and cisternographic finding and discuss the clinical picture, proposed pathophysiologic mechanisms and potential treatment.     

Preovulatory overripeness of the oocyte as a cause of ovarian dysfunction in the human female

A variety of gynaecological phenomena such as menstrual disorders, infertility and premature menopause are associated with ovarian dysfunction. In this paper, a factor is considered that may play a role in the aetiology of ovarian dysfunction. Animal research has shown that preovulatory overripeness of the oocyte may cause various developmental and chromosomal anomalies. Among the developmental anomalies observed in amphibia and fish are a number of gonadal aberrations, often occurring in otherwise normal specimens. This may be the consequence of a degeneration of the 'germinal cytoplasm', cytoplasmic structures located in the vegetative pole region of the oocyte, destined to become part of future primordial germ cells. Indirect evidence suggests that preovulatory overripeness of the oocyte also plays a significant role in human reproductive failure. An increased risk of preovulatory overripeness is expected during periods of endocrine irregularities, such as the first postmenarcheal years, the last premenopausal years, the first months after a pregnancy and, possibly, during certain seasons. If the overripeness-induced gonadal maldevelopment observed in animals also occurs in humans, this may explain variations in reproductive function according to month of birth, as observed in women. It is hypothesized that females conceived during periods of maternal endocrine irregularities face an increased risk of ovarian dysfunction through overripeness-induced gonadal maldevelopment.     

Structural features of thyroid hormone response elements that increase susceptibility to inhibition by an RTH mutant thyroid hormone receptor

The chicken lysozyme silencer F2 (F2) thyroid hormone response element (TRE) contains an unusual everted palindromic arrangement, has a high affinity for thyroid hormone receptor (TR) homodimers, and is especially sensitive to dominant negative inhibition by, the T3 resistance (RTH) mutant TR beta P453H. We used various TREs and TR mutations to determine the mechanisms for this sensitivity. Changing the F2 orientation from an everted palindrome to a direct repeat with a 4-bp gap (DR+4) (F2-DR) decreased the sensitivity to inhibition at high T3 concentrations, while a loss of this sensitivity occurred with a palindromic arrangement of these same half-sites. F2 contains the dinucleotide TG 5' to each consensus half-site conforming to the optimal TR-binding octamer, YRRGGTCA. A T to A change in position 1 of both F2 half-sites markedly reduced T3-induction, yet only slightly reduced TR homodimer or TR-retinoid X receptor (RXR) heterodimer binding. The TR beta ninth heptad mutation, L428R, prevents TR heterodimerization with RXR and eliminates the inhibitory effect of the P453H mutant TR on the F2-DR, but not the F2 element. Structural features of a TRE that favor strong TR binding of both TR homodimers and TR-RXR heterodimers containing the mutant TR, such as the everted palindromic conformation or the optimal TR-binding consensus octamer, enhance the sensitivity of a TRE to inhibition by the mutant TR. Thus, both half-site orientation and sequence contribute to the sensitivity of a given TRE to dominant negative inhibition by a mutant TR.     

The immunomodulating action of cyclosporin A in vitro and in vivo on the lymphocytes of patients with alveolitis

The effect of various concentrations of ofloxacin, ciprofloxacin and lomefloxacin on the morphokinetic parameters of the cellular elements of the lung tissue of intact animals (mice, guinea pigs and dogs) was studied under the conditions of the tissue culture. It was shown that in a concentration of 100 micrograms/ml and the exposure time of 24 hours the drugs had no effect on the mobility and structure of the lung tissue cellular elements. When the drugs were used in a concentration of 100 micrograms/ml the mobility rate of the lymphocytes and macrophages proved to by markedly retarded by the end of the 24th hour. In a concentration of 1000 micrograms/ml the drugs killed the cell culture. There were detected no specific differences in the effect of the fluoroquinolones on the cellular elements of the lung tissue of the intact animals.     

Opportunities for promoting palliative medicine in cancer research

OBJECTIVE: To study the effect of cisplatin on plasma concentrations and urinary excretion of carnitine in ten patients with different malignancies treated with chemotherapy. METHODS: Carnitine concentrations were determined using a radioenzymatic assay and other metabolites by routine methods of clinical chemistry. Renal clearances were calculated by dividing urinary excretions by the respective plasma concentrations. RESULTS: Before treatment, all patients had a normal plasma carnitine concentration. During treatment with cisplatin, the plasma total carnitine concentration increased by approximately 30% and normalized 7 days after stopping therapy. Urinary excretion of total carnitine increased by a factor of 10 during cisplatin administration and also normalized 7 days after cessation of chemotherapy. This increase was due to excretion of both free carnitine and acylcarnitine and averaged approximately 1 mmol carnitine per day. Similarly, urinary clearance of total carnitine was increased during therapy with cisplatin by a factor of approximately 8 and returned to normal 7 days after chemotherapy. In comparison, patients with similar malignancies treated with radiotherapy showed no significant increase in renal carnitine excretion. Similar to urinary excretion of carnitine, excretion of glucose and phosphate, two metabolites also reabsorbed by the proximal tubule of the nephron, was increased during therapy with cisplatin. There was a strong linear correlation between urinary excretion of free carnitine and acylcarnitines. CONCLUSIONS: Treatment with cisplatin is associated with a tenfold increase in renal carnitine excretion, most likely due to inhibition of carnitine reabsorption by the proximal tubule of the nephron. Well-nourished patients support this loss of carnitine even after repeated cycles of chemotherapy without developing hypocarnitinaemia. However, cachectic patients with decreased dietary carnitine uptake may develop carnitine deficiency when treated repeatedly with chemotherapies including cisplatin.