GLUCOSE METABOLISM OF ISOLATED MAMMALIAN ISLETS OF LANGERHANS

GLUCOSE METABOLISM OF ISOLATED MAMMALIAN ISLETS OF LANGERHANS

633 in the urine, immunological tests, effects on growth, scholastic ability, and exercise tolerance (Alves 1958, Jordan and Randall 1962, Nagaty et a...

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633 in the urine, immunological tests, effects on growth, scholastic ability, and exercise tolerance (Alves 1958, Jordan and Randall 1962, Nagaty et al. 1962, Pitchford et al. 1962, Forsyth and Bradley 1964b, Nnochiri 1965). None of these workers have reported the pyelographic appearance after therapy, even though in some cases pyelograms were apparently available before

parasitological findings

treatment was

begun.

Adult patients with longstanding vesical schistosomiasis may be left with severe urological sequelae, even after the worms have been eliminated by specific drug therapy (Forsyth 1958). Fibrotic stenosis of the ureter, for example, may persist, and the resulting back pressure may lead to progressive renal damage; these patients need surgical treatment for the relief of ureteric obstruction. But how far these observations in adults can be extrapolated to children is uncertain. Forsyth and MacDonald (1965) suggested that the prognosis was grave in Tanzanian children in whom hydronephrosis had developed and " that the only prospect of modifying this would be by specialist surgical intervention ". Before recommending surgical treatment on a mass scale, it seems to us important to obtain further information about the scope and the limitations of chemotherapy. Certainly, our initial results with drug treatment are encouraging, even though the final outcome is still to be determined by a longer follow-up. It may be that the obstruction in these children was not due to rigid fibrotic stenosis, but rather to granulomatous lesions of the lower ureter, ureteric orifice, or bladder which can resolve without significant residual damage. In this

Fig. 4-Case 4: A, left kidney showing back-pressure changes; B, return to

normal appearance 14 weeks after start of treatment.

it is interesting to note that the granulomatous lesions which show up as nodular filling defects of the bladder resolve rapidly after treatment; it is not unlikely that they also disappear spontaneously. This preliminary report is based on a small number of cases that have been observed for a relatively short period, but the encouraing results justify this early report. If our findings are confirmed on further follow-up and by studies elsewhere, there should be a reassessment of context

current

therapeutic policies.

We are grateful to Dr. C. Lambert, of Ciba Laboratories, for the generous supply of ’Ambilhar’; and to Dr. T. I. Francis of the department of medicine, University of Ibadan, for his cooperation in the care of some of these patients. This investigation received financial support from the World Health Organisation. REFERENCES

Alves, W. (1958) Cent. Afr. J. Med. 4, 15. Forsyth, D. M. (1958) Lancet, ii, 990. Bradley, D. J. (1964a) ibid. ii, 169. (1964b) ibid. p. 171. MacDonald, G. (1965) Trans. R. Soc. trop. Med. Hyg. 55, 171. H. Gilles, M., Adeniyi-Jones, C. C., Anand, J., Braband, H., Cockshott, W. P., Cowper, S., Lindner, R., Lucas, A., Muller, J., Wilson, A. (1965) Ann. trop. Med. Parasit. 59, 441. Jordan, P., Randall, K. (1962) J. trop. Med. Hyg. 65, 1. Lambert, C., Ferreira, F. S. C. (1965) Bull. Wld Hlth Org. 32, 73. Nabawy, M., Gabr, M., Ragab, M. M. (1961) J. trop. Med. Hyg. 64, 314. Nagaty, H. F., Rifaat, M. A., Khalil, H. M., Morsi, T. A. (1962) ibid. 65, 91. Nnochiri, E. (1965) W. Afr. med. J. 14, 129. Pitchford, R. J., Beugger, J. E. A., Pretorius, H. P. (1962) S. Afr. med.J. 36, 37. -

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GLUCOSE METABOLISM OF ISOLATED MAMMALIAN ISLETS OF LANGERHANS R. J. JARRETT M.A., M.D. Cantab. H. KEEN M.B. Lond., M.R.C.P. From the Department of Medicine,

MOST of

our

Guy’s Hospital, London, S.E.1

information about the metabolism of

pancreatic islet-cell tissue has been obtained from studies with the " principal islet " of teleost fish (Field and Lazarow 1960, Hellmann and Larsson 1961, Humbel and Renold 1963). There is little evidence, however, that the fish islet responds to the same stimuli as mammalian islets as far as insulin synthesis and secretion are concerned. Keen, Sells, and Jarrett (1965) have described a method of obtaining islets by microdissection of the pancreas of rats in which acinar atrophy has been induced by ligation of the pancreatic duct. We present here the results of studies of glucose oxidation by the isolated islets. Fig. 3-Case 8: A, severe back-pressure changes in right kidney; B, 26 weeks after treatment, striking improvement.

Methods obtained by the method of Keen, Sells, and Jarrett (1965). The cells were incubated in centre wells

Islets

were

634 TABLE I-EFFECT OF GLUCOSE CONCENTRATION UPON 14C02 PRODUCTION, FROM LABELLED GLUCOSE, BY ISOLATED ISLETS OF LANGERHANS. THE VALUES ARE THE MEAN OF DUPLICATE ESTIMATES. SPECIFIC ACTIVITY OF GLUCOSE APPROXIMATELY 0-1 U.C PER MG.

in

toluene)

and counted in

an

spectrometer (Packard). Results "

automatic are

liquid-scintillation expressed as counts per

"

minute above background (which was estimated in flasks, containing medium but no tissue, carried through the same procedure). Re-collection of I4C02 as described greatly lowered the " background " counts. Islets were incubated at varying concentrations of glucose. The specific activity of the glucose was, however, the same in any one experiment-approximately 0-1 tC per mg.

Results

the rubber stopper of a counting-vial. The incubation medium was 0 15 ml. Krebs Ringer bicarbonate buffer containing 2 mg. per ml. crystalline bovine albumin, unlabelled glucose, and glucose uniformly labelled with 1’C or specifically labelled in the 1 or 6 position. Batches of ten islets were incubated at 37°C in a shaking incubator for three hours. At the end of the incubation, metabolism was stopped and the 14C02 was released by the injection of 0-2 ml. N hydrochloric acid into the centre well. 14C02 was collected overnight in 1 ml. saturated barium hydroxide injected into the base of the vial. On the next day, the centre well was replaced by one containing 0-75 ml. phenylethylamine solution (Woeller 1961) and the HC02 was released from the barium hydroxide by the injection of 1 ml. N hydrochloric acid into the vial. The "C02 was then re-collected into phenylethylamine, which was later added to 8-0 ml. phosphor (PPO [2,5-diphenyloxazole] 0-4% and POPOP [1,4-bis-(2-[5-phenyloxazolyl])-benzene] 0-01%

suspended from

We reported previously (Keen, Sells and Jarret, 1965) that 14C02 production from [14C]-1-glucose continued in a linear fashion for at least four hours of incubation and that 14CO2 production increased with increasing glucose concentration. Both of these findings have subsequently been confirmed using uniformly labelled glucose. An additional early finding that there was a comparatively greater TABLE II-THE EFFECT OF A RANGE OF MEDIUM GLUCOSE CONCENTRATION UPON PRODUCTION FROM LABELLED GLUCOSE BY ISOLATED

14CO2

ISLETS OF LANGERHANS

increase in 14C02 from

[14C]’_1 -glucose than from [14C]-6glucose in high glucose medium requires modification in the light of subsequent experiments. Table i shows the results of three separate experiments in which oxidation of I14C]- 1-glucose and [14C]-6-glucose was compared at glucose concentrations of 20 and 200 mg. per 100 ml. In each experiment there was a greater increase in 14COj production from [C]-6-glucose. A glucose concentration of 20 mg. per 100 ml. is low compared with the fastingblood-glucose of the rat-approximately 100 mg. per 100 ml. The relative 14C02 production was therefore compared over the range 50-400 mg. glucose per 100 ml in two further experiments. The pooled results are shown in the accompanying figure and the individual results are shown in table 11. For comparison, the pooled results oi two similar experiments, substituting pieces of rat epididymal fat, are shown in the figure. The difference ir. the effect of glucose concentration on glucose oxidation b) the two tissues is striking. Oxidation, by the islets, oj glucose labelled in both the 1 and 6 positions is greatly stimulated by increasing the glucose concentration. The increase in [14C]-6-glucose oxidation is comparativel) greater but, as can be seen from tables i and n, the absolute yield of 14C02 is greater from [14C]-1-g1ucose a1 all concentrations. Discussion

The effect of medium glucose concentration upon 1°COz production from [UC]-I-g1ucose and ["C]-6-Rlucose by isolated islets of Langerhans and rat epididymal fat.

is

"C02 production at a glucose concentration represented as 1 on the ordinate.

of 50 mg. per 100 ml.

In mammals, glucose is the predominant stimulus t( insulin release and, presumably, synthesis. Thus it is oj great interest that increasing the glucose concentratior results in a notable stimulation of glucose oxidation b3 islet tissue of the rat. Field and Lazarow (1960) founc that the oxidation of [14C]-6-glucose by fish islets continued to increase as the glucose concentration waf increased from 12-5 to 200 mg. per 100 ml., but that the oxidation of [14C]-1-glucose reached a maximum at glucose concentration of 25-50 mg. per 100 ml. Ir. contrast, glucose oxidation by slices of an islet-cell tumour was not increased by increasing the glucose concentratior

635

from 125 to 500 mg. per 100 ml. (Field 1964). This behaviour of islet-cell tumour in vitro is not particularly surprising in view of its in-vivo independence of the plasma-glucose with respect to insulin release. The different behaviour of the fish islets may be related to the different role of insulin in the carbohydrate metabolism of the fish (Tashima and Cahill 1964). Our finding that 14C02 production from [14C]-1-glucose increased with increasing glucose concentrations from 50 to 400 mg. per 100 ml. supports the hypothesis of Field et al. (1960) that the hexose monophosphate pathway may be concerned in some way with insulin synthesis, perhaps by providing ribose for nucleic-acid synthesis. The greater increase in oxidation of [14C]-6-glucose with increasing glucose concentration may, by contrast, be related to insulin release.

Summary In in-vitro

experiments on isolated mammalian islets of

the glucose concentration of the medium results in a considerable stimulation of glucose oxidation. At medium-glucose concentrations of 20-400 mg. per 100 ml. the increase in 14C02 production is greater from [14C]-6-glucose than from [14C]-1-glucose, but the absolute yield of 14C02 from [14C]-l-glucose is greater at all concentrations. The findings support the hypothesis that the hexose monophosphate pathway is related to insulin synthesis.

Langerhans, increasing

REFERENCES

Field, J. B. (1964) Am. J. Med. 36, 867. Lazarow, A. (1960) Biol. Bull. 119, 313. — Johnson, P., Herring, B., Weinberg, A. N. (1960) Nature, Lond. 185, -

468.

Hellmann, B., Larsson, S. (1961) Acta. Endocr. 38, 303. Humbel, R. E., Renold, A. E. (1963) Biochim. biophys. Acta. 74, 84. Keen, H., Sells, R., Jarrett, R. J. (1965) Diabetologia, 1, 28. Tashima, L., Cahill, G. F. Jr. (1964) Congr. int. Diabetes Fed. and Excerpta med. (1964) no. 74, 140 (abstract). Woeller, F. H. (1961) Analyt. Biochem. 2, 508.

NEONATAL THYROTOXICOSIS ASSOCIATED WITH MATERNAL HYPOTHYROIDISM M.B.

Fig. 1--Exophthalmos in mother.

sided abdominal pain for 1 day. A more detailed history revealed that over the previous 18 months she had noticed that she had become mentally slower, had gained a stone in weight, and had become intolerant to cold. On examination, in addition to a loaded bowel, there was facial puffiness, dry skin, and a moderately enlarged firm goitre with an easily palpable pyramidal lobe. At this time her serum-cholesterol level was 415 mg. per 100 ml.; a thyroid-precipitin test was negative; and a barium-enema showed no structural abnormality. The clinical diagnosis was severe constipation resulting from hypothyroidism due to excessive administration of iodide; the patient responded well to enemas and the administration of sodium thyroxine; her bowel symptoms and the clinical features of hypothyroidism subsided within 2 months. She was then taken off her elixir sibec and the sodium thyroxine was discontinued but she again became clinically hypothyroid. She refused to have a thyroid biopsy to elucidate the nature of the goitre, and, since she insisted on restarting her elixir sibec, thyroxine therapy was reinstituted and gradually increased to 0-1mg. twice daily. In addition, during her second, but not her third, pregnancy, she was given steroids (betamethasone) intermittently to control her asthmatic symptoms. In December, 1963, she complained of prominence of the left eye; on examination she had exophthalmos of the left eye and bilateral lid lag (fig. 1). X-ray of skull and orbits revealed no structural cause for the exophthalmos. On the assumption that thyroid-stimulating hormone (T.S.H.) might be a factor in the production of eye signs, the dosage of thyroxine was increased to 0-1 mg. t.i.d. in an attempt to suppress completely

JOHN A. THOMSON Glasg., M.R.C.P., M.R.C.P.G.

SENIOR REGISTRAR, UNIVERSITY DEPARTMENT OF MEDICINE, ROYAL INFIRMARY, GLASGOW, C.4

IAN D. RILEY M.D., B.Sc. Leeds, D.C.H., F.R.C.P.G., M.R.C.P. CONSULTANT

PÆDIATRICIAN, STOBHILL GENERAL HOSPITAL,

GLASGOW

thyrotoxicosis is a rare disease; in all previously reported instances the affected child was born to a mother who had active thyrotoxicosis or who had been thyrotoxic (McKenzie 1964). The present case-report of a thyrotoxic child born to a mother who was under maintenance treatment with sodium thyroxine for hypothyroidism is, so far as we are aware, unique. NEONATAL

Case-report The Mother The mother is aged 31 years; from the age of 3 she has had chronic asthma, for which for the past 25 years she has been taking the iodide-containing preparationElixir Sibec’ (sodium-iodide content 3-588% w/v) in the average dosage of 30 ml, daily. When she was first seen at the Royal Infirmary, Glasgow, in 1961 at the age of 26 she was thought to have an acute surgical disorder from her history of constipation for 6 days and left-

Fig. 2-Baby

on

7th day of life.