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Cell membrane transport enzymes in cultured dermal fibroblasts from progeroid donors: a comparison to other human fibroblasts.

Cell membranes from progeroid fibroblasts had an elevated Na+, K+ ATPase. Ca++ ATPase and gamma-glutamyl transpeptidase were markedly decreased in progeroid fibroblast membranes. 5'-nucleotide phosphatase was unchanged, compared to age- and sex-matched normal fibroblast membranes. Fetal lung fibroblasts and dermal fibroblast from myotonic dystrophy victims had enzyme activities similar to those of the normal dermal fibroblasts.

Adolescent↗

Cellular models and tissue equivalent systems for evaluating the structures and significance of age-modified proteins.

The accumulation of modified proteins in aging is well documented in many aging models. For example, the deamidated isoforms of triosephosphate isomerase accumulate in: (a) old erythrocytes, (b) fibroblasts from old donors, (c) fibroblasts aged in vitro, (d) premature-aging syndromes and (e) old cells in the eye lens. However, a fundamental remaining question is: 'Do such modified proteins interfere with cellular function?' It has been difficult to assess this question at the molecular level using whole-organism models and equally frustrating to evaluate the physiological significance of such changes using classical cellular models. Tissue equivalent systems (TES) provide an opportunity for examining the molecular basis and physiological consequences of modified proteins during aging. TES are composed of differentiating and proliferating heterogeneous cell types with symbiotic cell-cell and cell-matrix interactions. They closely resemble, both morphologically and functionally, the tissues from which they were derived. Aging studies utilizing TES can provide information on modifications of protein structures, isozyme patterns, enzymes of the cellular environmental protection system and metabolic parameters which may regulate protein synthesis and degradation.

Adenosine Triphosphate↗

Overexcretion of low-sulphated chondroitin sulphate in the urine of the patient resembling progeroid.

We report an unusual case with mental retardation, short stature, sparse scalp hair, prominence of scalp veins, atrophy of subcutaneous fat, pterygia of the neck and loose skin. The patient excreted greater amounts of low-sulphated chondroitin sulphate (LSC) in the urine than age-matched controls. The pattern of glycosaminoglycan in serum and its synthesis by the patient fibroblasts were normal. Collagen, elastin and decorin mRNA levels in the patient fibroblasts were also unaltered. These results suggest that this patient seems to be different from Lowe's syndrome and decorin-deficient progeroid. An abnormal LSC metabolism may be partially responsible for the pathology of these syndromes.

Abnormalities, Multiple↗

Impaired insulin binding and excess glucose transport in fibroblasts from a patient with leprechaunism.

The insulin receptor, though understood in fine molecular detail, remains problematic with regards to its mechanism(s) of cellular signalling. To better understand the normal mechanisms of plasma membrane signalling by insulin, we studied the family of a patient with insulin resistance, hypoglycemia and leprechaunism. Skin fibroblasts were cultured from the proband and his parents. High-affinity insulin binding to the proband's cells was absent. Both parents' fibroblasts showed high-affinity insulin binding intermediate between the controls and the proband. Thus impaired binding conformed to an autosomal recessive pattern of inheritance. The transport of neutral amino acids by the proband's cells was comparable to controls and was insulin-sensitive. By contrast, hexose transport by the proband's fibroblasts was very high and insulin-insensitive. This increased uptake was due to an increased number of glucose transporters on the plasma membrane and to a posttranslational mechanism. Similar levels of glucose transporter mRNA were observed in control and mutant cells. Thus, this inborn error of the insulin receptor offers unique insight into a regulatory signal by its alpha subunit which, when altered, results in constitutively increased glucose transport.

Abnormalities, Multiple↗

Congenital coronary artery obstruction associated with aortic anomalies in children: report of two cases.

Coronary arterial obstruction associated with congenital aortic valve disease is rare in children. We studied two children with aortic valve disease and symptoms of coronary insufficiency. Cineangiography revealed localized obstruction of the proximal left coronary artery. In one patient, a membrane-like structure partially covered the left sinus of Valsalva, almost isolating the ostium of the left coronary artery; the other patient had severe stenosis of the proximal left coronary artery and a congenitally hypoplastic left coronary cusp. Surgical repair was successful in both cases. Symptoms of myocardial ischemia in children with aortic valve disease should be investigated promptly to exclude obstruction of the coronary arteries.

Aortic Valve↗

Children who age rapidly--progeroid syndromes: case report of a new variant.

A case report of an apparently unique progeroid syndrome is reported here. Major clinical characteristics included growth failure with onset of senility in the early teens, atrophic skin, hypogonadism, and retinal and vascular sclerosis. Mental retardation was present, but could have been attributable to trauma. The replicative life spans of several lines of cultured skin fibroblasts were within the normal range, in contrast to the limited life-spans of such cultures from patients with Werner's syndrome, whom our patient most closely resembles. Also, in contrast to Werner's syndrome, our patient did not have white or gray hair or cataracts.

Adult↗

Impaired regulation of gonadotropins leads to the atrophy of the female reproductive system in klotho-deficient mice.

klotho-Deficient mice exhibit a syndrome resembling human premature ageing, with multiple pathological phenotypes in tissues including reproductive organs. It was proposed that Klotho might possess the hormonal effects on many organs. In this study, the female reproductive system of klotho mice was examined to reveal the mechanism that brought the female sterility by histological and molecular approaches. We observed cessation of ovarian follicular maturation at the preantral stage and the presence of numerous atretic ovarian follicles and atrophic uteri. In situ hybridization analysis revealed that LH receptor and aromatase P450 were not expressed in the ovaries. These results suggest the impairment of gonadal development during the antral transition process. We next addressed the responsible organs for the failure of antral transition. Transplantation of klotho ovaries to wild-type mice resulted in the ability to bear offspring. Administration of FSH or GnRH induced advanced maturation of ovaries and uteri in klotho mice. These results indicate that the female reproductive organs in klotho mice are potentially functional and that klotho gene deficiency leads to the atrophy of reproductive organs via impairment of the hypothalamic-pituitary axis. Absence of the estrus cycle and constant low trends of both FSH and LH levels were found in female klotho mice. Immunohistochemical analysis revealed that the production of both FSH and LH were decreased in pituitary gland. Taken together, our findings suggest the involvement of klotho in the regulatory control of pituitary hormones.

Animals↗

Somatomedin C-binding and action in fibroblasts from aged and progeric subjects.

Aging is associated with diminished cell growth, which has been ascribed in part to decreased cellular responsiveness to serum mitogens. To investigate whether there is an age-related loss of responsiveness to somatomedin-C (SM-C), we studied SM-C binding and action in early passage fibroblasts from normal donors, aged 7-96 yr, and one progeric subject. SM-C stimulated [3H]thymidine incorporation 4- to 16-fold in young cells, 4- to 17-fold in aged cells, and 4- to 11-fold in progeric cells. SM-C was synergistic with 0.25% human hypopituitary serum in stimulating [3H]thymidine incorporation in all cell lines. Dose-response curves for SM-C stimulation of thymidine incorporation were not significantly altered in aged or progeric cells. Half-maximal responses occurred at 5-15 ng/ml SM-C for all cell lines. [3H]Thymidine incorporation results were supported by cell replication studies. In addition, binding of [125I] SM-C was virtually identical in all cell lines, with 50% displacement at 2-5 ng/ml SM-C. Thus, in vivo aging does not appear to be associated with either an alteration in SM-C receptors or a diminished cellular responsiveness to SM-C's mitogenic effects.

Adolescent↗

[Aging and endocrine pancreas (author's transl)].

To test the hypothesis that diabetes is a form of accelerated aging, the following observations were made. 1) The incidence rate of diabetes mellitus had its peak at around 50 years of age with a gradually decreasing rate thereafter. This was clearly different from the manner of incidence of such disease as arteriosclerosis which increased with advancing age. 2) 100g of the oral glucose tolerance test performed on elderly subjects aged 60 to 89 years revealed high incidence of abnormal tolerance, 21% diabetic and 53% borderline types. 3) The insulin secretory capacity to glucose load of subjects was not different from that of young and middle-aged subjects from 20 to 49 years old. Therefore, decreased tolerance to glucose load could not ba ascribed to deficient insulin secretion. 4) No abnormality of glucagon response to glucose load was found in the old. 5) Serum beta-N-acetylhexosaminidase activity was not increased in elderly subjects, again contrasting with the increased activity found in diabetics. 6) Both glycolytic and gluconeogenic enzyme activities were decreased in the liver of aged rats. 7) No specific abnromality in insulin secretory response was observed in Werner's syndrome which might be considered to be a model for aging. All the above observations do not support the aforementioned hypothesis. Abnormality of glucose tolerance frequently observed in elderly subjects appears to be caused by other pathogenesis than diabetes mellitus.

Adolescent↗

A new look at the management of the oculo-mandibulo-facial syndrome.

The authors review the literature on the oculo-mandibulo-facial syndrome and present the case of a six-year-old boy with congenital cataracts, microphthalmos, nystagmus, failure to thrive, dysmorphic features with a tiny pinched nose, mandibular hypoplasia, microstomia, double chin, chronic snoring, recurrent respiratory infections and dental problems. Chronic obstructive sleep apnoea with decreased oxygen saturation was present. Optimal medical management of OMFS-patients is described.

Abnormalities, Multiple↗