Dihydrotachysterol: a calcium active steroid not dependent upon kidney metabolism.

The activity of dihydrotachysterol and cholecalciferol was determined in nephrectomized or sham-operated vitamin D-depleted rats using in vitro transport of calcium and phosphate by everted intestinal preparations as the index of physiologic response. The activity of dihydrotachysterol was not reduced by absence of the kidneys whereas that of cholecalciferol was markedly inhibited so that at least a 10-fold greater dose of the latter was necessary to produce an equivalent effect in the nephrectomized rat as in the control. Dihydrotachysterol is therefore equipotent with cholecalciferol in the anephric rat although much less active in the intact animal.

Rapid reduction and return of surface insulin receptors after exposure to brief pulses of insulin in perifused rat hepatocytes.

Hepatic receptors are normally exposed to discrete pulses of insulin and glucagon at intervals of 8 to 16 min. Using a multicolumn system for perifusing hepatocytes, we investigated the effect of this pattern on the normal processing of the insulin receptor. Surface-receptor binding was measured in acid-washed cells harvested from individual columns. The number of high-affinity surface receptors fell to a nadir 1 min after the end of a 3-min square-wave pulse of insulin. The maximum reduction reached 45% of baseline at amplitudes of 1000 microU/ml or above. The number of surface binding sites returned to baseline 15 min after the end of the pulse, but the affinity constant of the high-affinity receptor was unchanged. The reduction of surface binding was dose dependent, with an ED50 of 251 +/- 34 microU/ml. Prolonging the pulse to 60 min did not affect the nadir or the rate of restoration of the surface-receptor population. The change in surface binding was reduced at 15 degrees C and abolished at 4 degrees C. After a pulse, the pattern of change was a period of rapid decline to a nadir (t1/2 less than or equal to 1 min) that persisted for 3-5 min, followed by restoration of surface binding that reached baseline in 10-15 min. This same pattern was present after six ED95 pulses delivered at intervals of 15 min. These data indicate that the internalization of hepatocyte surface receptors and their recycling and reinsertion into the plasma membrane can be entrained to pulses at the physiologic pulse frequency.

Insulin pulses less effective than continuous insulin in inhibiting PEPCK mRNA levels stimulated by cAMP and dexamethasone in perifused hepatoma cells.

Hepatic glucose production is stimulated in vitro twice as effectively by pulsatile as by continuous glucagon, given equivalent time-averaged doses. Efficacy studies of pulsatile insulin have yielded conflicting results. In the rat hepatoma cell line H-4-II-E-C3, insulin rapidly (t1/2 15 min) inhibits transcription of the gene and lowers mRNA levels for the gluconeogenic enzyme. PEPCK via a receptor-mediated process. We attached H-4-II-E-C3 cells to Cytodex-3 microcarriers and used a perifusion column system to test whether pulsatile insulin is more or less effective than equivalent time-averaged doses of continuous insulin. PEPCK transcription was induced by inclusion of cAMP analogue 8-(4-chlorophenyl-thio)-cAMP (0.1 mM) and dexamethasone (0.5 microM) in the perifusion medium. Three columns were exposed either to continuous, pulsatile, or no insulin. After 3 h, total nucleic acid was extracted, and mRNA(PEPCK) was measured with a sensitive-solution hybridization assay. Continuous insulin inhibited PEPCK expression in a dose-dependent fashion with EC50 1 x 10(-11) M. Equivalent time-averaged amounts of insulin delivered as pulses achieved significant inhibition but less effectively than continuous insulin. The apparent EC50 for pulsatile insulin increased from 2 x 10(-11) M to 5 x 10(-11) M as the oscillatory period was raised from 5 to 20 min, respectively. These observations suggest that insulin-mediated inhibition of PEPCK gene transcription is diminished by a pulsatile mode of administration in marked contrast to the pulse enhancement demonstrated for glucagon-mediated hepatic glucose production.

Nodular fasciitis of the nose in a child.

Nodular fasciitis is an unusual benign tumour composed of fibroblasts. It presents as a rapidly growing mass arising from subcutaneous or deep fascia. Less than 20% of cases occur in children. Diagnosis can only be made by histopathological examination of a biopsy of the lesion. A case of nodular fasciitis presenting as a mass arising from the right nasal cavity in a 19-month-old female is presented. The lesion was successfully eradicated by surgical removal. There has been no recurrence at 4-year review. Nodular fasciitis is a benign condition that may mimic malignancy clinically and histologically. Recognition of this condition is important to avoid unnecessarily aggressive treatment. Relevant clinical, radiological and histological features are discussed.

Adenoidectomy in a girl with haemophilia.

Haemophilia A is a sex-linked inherited disease in which those affected are usually males, and females are usually asymptomatic carriers. This paper presents a haemophilia A carrier who has a low factor VIII level first, to remind readers that females can have low factor VIII levels with consequent increased tendency to bleed; second, to stress the importance of routine questioning regarding a bleeding tendency in the patient or the patient's family and third, to illustrate the importance of pre-operative diagnosis to allow adequate correction of the defect so that surgery such as adenoidectomy can be undertaken with safety in such a patient.

Further experience with a straight, vertical incision for placement of cochlear implants.

Experience with a straight, vertical incision for cochlear implantation in 168 patients of all ages is reported and comparison made with previous experience using a 'C' shaped incision in 173 patients with regard to complications encountered. With the straight incision the only complication was a wound infection which settled in one week; this is in contrast to the 'C' shaped incision, which was associated with a number of serious complications. The straight incision also compared favourably with the other incisions commonly used for cochlear implantation and appears to offer advantages over them.

A new incision for placement of cochlear implants.

A straight, vertical post-aural incision for the 'Cochlear' multichannel cochlear implant has been evaluated in 52 patients (20 adults and 32 children). Nineteen of the children were under three years of age and five of these were under two years of age. The 7 cm long incision is placed approximately 3 mm behind the post-auricular crease and runs from the tip of the mastoid to a point 3 cm above the superior attachment of the pinna. The incision heals within several days. Because the incision is straight interruption of the blood supply to the flaps raised is the least possible. This also minimizes the possibility of scalp necrosis and implant extrusion. The likelihood of infection is reduced by the small size of the incision, minimal soft tissue dissection and small amount of dead space. Rapid healing has occurred in all cases despite infection in one.

Cochlear implant extrusion in a young child--a preventive procedure.

A Cochlear Mini System 22 Channel cochlear implant extruded through the skin of a young girl. The implant was saved by use of a transposition flap. Extrusion appeared to be due to pressure necrosis from the implant on the overlying tissues. It is believed that this problem can be prevented by angulation of the implant before insertion so that it conforms to the curvature of the skull, so avoiding pressure on the tissues. The method of angulation is described.

Nasopharyngeal cyst simulating Kaposi's sarcoma in an HIV-infected patient.

A case of nasopharyngeal cyst in a 30-year-old male homosexual intravenous drug user infected with the human immunodeficiency virus (HIV) is presented. The similarity in clinical presentation of nasopharyngeal cyst and Kaposi's sarcoma is discussed.

Subperiosteal abscesses of the orbit due to sinusitis in childhood.

This paper reports 16 cases of subperiosteal abscesses of the orbit due to acute sinusitis in childhood. They comprise 12.4% of 129 patients presenting with an 'acute orbit'. Acute ethmoidal sinusitis was the predominant cause. The typical clinical features, as well as CT scanning of the paranasal sinuses, orbit and brain, should assist in early diagnosis. If possible, the subperiosteal abscess and sinuses should be drained before loss of visual acuity or intracranial complications occur. Streptococcus milleri was the pathogen most commonly cultured. One patient in this series had intracranial complications, but no other patients had major complications and there were no deaths.

Rickets then and now.

Since the introduction of irradiated ergosterol into our food supply, nutritional vitamin D-deficiency rickets has become an uncommon disease. However, skeletal disorders due to abnormalities of vitamin D function still occur. These disorders can now be classified more exactly into two groups: those in which there is a deficiency of the active metabolite of vitamin D, 1,25-dihydroxyvitamin D, and those in which there is an abnormality of renal tubular function resulting in renal hypophosphatemia despite normal vitamin D metabolism. The various entities of these two groups are described and the theoretical basis of their treatment given.