Growth hormone releasing factor: comparison of two analogues and demonstration of hypothalamic defect in growth hormone release after radiotherapy.

Human pancreatic growth hormone releasing factor (hpGHRF(1-40] stimulates the release of growth hormone in normal subjects and some patients with growth hormone deficiency. A study comparing the shorter chain amidated analogue hpGHRF(1-29) with an equivalent dose of hpGHRF(1-40) in seven normal subjects showed no significant difference in growth hormone response between the two preparations. Six patients with prolactinomas were also tested; these patients had received megavoltage radiotherapy previously but had developed growth hormone deficiency as shown by insulin induced hypoglycaemia. In all six patients 200 micrograms hpGHRF(1-40) or hpGHRF(1-29)NH2 produced an increase in the serum growth hormone concentration. These data suggest that hpGHRF(1-29)NH2 may be useful for testing the readily releasable pool of growth hormone in the pituitary and that cases of hypothalamo-pituitary irradiation resulting in growth hormone deficiency may be due to failure of synthesis or delivery of endogenous GHRF from the hypothalamus to pituitary cells.     

Medical care in a tropical national reference and teaching hospital: outline study of cost-effectivenees.

During a 28-day prospective audit the cost-effectiveness of treatment in three types of medical wards in a large tropical teaching hospital was assessed. Patients with chronic diseases such as rheumatic heart disease were more expensive to treat than those with acute, curable illnesses such as malaria. It was concluded that the cost of providing treatment could not be reduced without affecting standards of medical care. The expense of running such a hospital might also be justified by its importnat function as a teaching hospital.     

Synthesis of (±)-16-thioketal and 16-keto prostaglandins

The synthesis of ((±)-16-thioketal and 16-keto PGE₂ methyl ester ( and ) is herein described.     

Nuclear DNA divergence among Lathyrus species

Among diploid Lathyrus species a threefold variation in nuclear DNA amount is attributable to differences in the amount of repetitive DNA. Cross reassociation among repetitive and among non-repetitive DNA fractions from different species shows substantial divergence in DNA composition. The divergence in base composition is correlated with nuclear DNA amount. The degree of divergence is of the same order of magnitude in both the repetitive and nonrepetitive fractions.     

Mechanisms of cellular adhesion : II. The interplay between adhesion, the cytoskeleton and morphology in substrate-attached cells

cAMP/theophylline exaggerates cell shape—whether the fibroblastic morphology of controls or the epithelioid shape of colchicine-treated cells. The ultrastructural basis is that cAMP/theophylline increases the number and linearity of microtubules and microfilament bundles, although where also treated with colchicine, the cells adopt a well-spread shape maintained by microfilament bundles alone. Since interference reflection microscopy shows that colchicine promotes the marked alignment of focal contacts (which terminate microfilament bundles) it is concluded that microtubules encourage angular cell form and modify the pattern of adhesions by influencing the directionality of microfilament bundle formation although they are inessential for the maintenance of the spread form or adhesion per se.     

Ouabain-insensitive salt and water movements in duck red cells. II. Norepinephrine stimulation of sodium plus potassium cotransport

Catecholamines induce net salt and water movements in duck red cells incubated in isotonic solutions. The rate of this response is approximately three times greater than a comparable effect observed in 400 mosmol hypertonic solutions in the absence of hormone (W.F. Schmidt and T. J. McManus. 1977 a.J. Gen. Physiol. 70:59-79. Otherwise, these two systems share a great many similarities. In both cases, net water and salt movements have a marked dependence on external cation concentrations, are sensitive to furosemide and insensitive to ouabain, and allow the substitution of rubidium for external potassium. In the presence of ouabain, but the absence of external potassium (or rubidium), a furosemide-sensitive net extrusion of sodium against a large electrochemical gradient can be demonstrated. When norepinephrine-treated cells are incubated with ouabain and sufficient external sodium, the furosemide-sensitive, unidirectional influxes of both sodium and rubidium are half- maximally saturated at similar rubidium concentrations; with saturating external rubidium, the same fluxes are half-maximal at comparable levels of external sodium. In the absence of sodium, a catecholamine-stimulated, furosemide-sensitive influx of rubidium persists. In the absence of rubidium, a similar but smaller component of sodium influx can be seen. We interpret these results in terms of a cotransport model for sodium plus potassium which is activated by hypertonicity or norepinephrine. When either ion is absent from the incubation medium, the system promotes an exchange-diffusion type of movement of the co-ion into the cells. In the absence of external potassium, net movement of potassium out of the cell leads to a coupled extrusion of sodium against its electrochemical gradient.     

Calorimetric and chiroptical evidence of aggregate-driven helix formation in carrageenan systems

Thermally induced, order-disorder transitions of iota- and kappa-carrageenan have been monitored by optical rotation and differential-scanning calorimetry in various ionic environments. Conformational ordering in kappa-carrageenan is observed only in the presence of cations that have been shown previously to promote helix-helix aggregation, and shows marked hysteresis between heating and cooling. Iota-carrageenan, by contrast, shows an order-disorder transition in the non-aggregating, tetramethylammonium salt form, at substantially lower temperature than for kappa-carrageenan, and without hysteresis. In the presence of potassium ions, which are known to promote aggregation, iota-carrageenan shows two distinct thermal-transitions, one without hysteresis at the same temperature as observed under non-aggregating conditions, and one with significant hysteresis close to the temperature of the kappa-carrageenan transition. We interpret these transitions as helix-to-coil and aggregated helix-to-coil, respectively. This interpretation is supported by measurements of the enthalpy changes of the transitions; ΔH values show a systematic increase with increasing aggregation and hysteresis. We conclude that the double helix of iota-carrageenan can exist as a stable entity in isolation, but may be further stabilised by aggregation, whereas the kappa-carrageenan helix is stable only when aggregated.     

Long survival in acute myelogenous leukaemia: an international collaborative study.

A group of 82 adult patients with acute myelogenous leukaemia had survived in continuous first remission for more than three years was studied. These long-surviving patients were being treated at 12 referral centres in Europe and the USA, and they were compared with other patients with acute myelogenous leukaemia from 10 of these centres. There was no clear difference in the amount of induction chemotherapy or the time taken to achieve remission. Immunotherapy was not found to improve chances of long-term survival. The 82 patients were also compared with a group of 115 patients who had no appreciable difference in the number of blood or marrow myeloblasts between these two groups at presentation, but the long survivors had significantly higher initial platelet counts and were slightly younger. The long survivors also tended to have a lower total white cell count at presentation and lower granulocyte counts; there was no obvious explanation for these differences. Eight of the 82 patients relapsed from three to four years after remission and two (of 69 patients) after four to five year. Thereafter relapse was rare, and it seems likely that some of the 40 patients who have survived for five years or more are cured.     

Newly biosynthesized cytochrome P-450 associated with the golgi apparatus from livers of rats induced with phenobarbital.

1. Cytochrome P-450 has been detected in preparations of golgi apparatus from the livers of phenobarbital-induced rats. 2. Newly biosynthesized cytochrome P-450 is also present in preparations of golgi apparatus. By using three different techniques to fractionate the golgi into vesicle contents and membrane components it was found that newly biosynthesized cytochrome P-450 is associated solely with the membrane fraction. 3. By investigating the susceptibility of cytochrome P-450, present in the golgi apparatus, to the action of trypsin it was found that the majority was oriented on the cytosolic face of the membrane.