Excretion of porphyrins and porphyrin precursors during neuromuscular paralysis produced by dithiobiuret

Urinary excretion of porphyrin precursors delta-aminolevulinic acid (ALA) and porphobilinogen (PBG) and total porphyrins was measured during intoxication of rats with 2,4-dithiobiuret (DTB), a chemical which produces delayed-onset neuromuscular weakness, in an attempt to ascertain whether or not DTB poisoning in the rat would serve as an animal model of the neurologic symptoms of acute intermittent porphyria. Daily administration of DTB (1 mg/kg/day, i.p.) produced flaccid skeletal muscle weakness first detected after 4 to 5 days of treatment. Onset of skeletal muscle weakness was associated with a significant increase in urinary excretion of ALA. The excretion of PBG and total porphyrin was also increased; however, the increase was not significant. The increase in porphyrins and porphyrin precursors was due to increased urine output which coincided with the onset of neuromuscular weakness; urinary concentrations of ALA, PBG, and porphyrins were not increased by DTB. Measurements of free-erythrocyte protoporphyrin, taken after 7 days of DTB treatment, indicated a significant elevation of free erythrocyte protoporphyrin concentration. The pattern of alterations in the heme precursors associated with DTB-induced paralysis in rats is quite different from that observed in humans afflicted with acute intermittent porphyria. Therefore, we conclude that DTB-induced paralysis in the rat does not represent an accurate animal model of acute intermittent porphyria.

Digestible energy and efficiency of feed utilization in rats treated with 2,3,7,8-tetrachlorodibenzo-p-dioxin

Treatment of male rats (300 to 325 g) with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, 15 or 50 micrograms/kg) caused dose-dependent reductions in body weight, feed and water intakes, and fecal output. Urine output, however, was not altered by TCDD. Fecal energy loss, as a percentage of daily feed energy intake (kcal/day), was similar in control and TCDD-treated rats as was the percentage of feed energy absorbed by the gastrointestinal tract, i.e., digestible energy. These findings dispel the long-standing proposal that a gross malabsorption syndrome is responsible for weight loss in TCDD-treated rats and place greater emphasis on hypophagia as the reason for weight loss. In support of a central role for hypophagia, it was found that control rats pair-fed to rats treated with a sublethal dose of TCDD (15 micrograms/kg) lost almost the same amount of weight. However, from 15 to 50 days post-treatment, the pair-fed animals consistently maintained their weight at a 10- to 15-g higher level than age-matched TCDD-treated rats. To determine why this weight difference occurs, the efficiency of feed utilization from Day 30 to 45 post-treatment in ad libitum fed control and TCDD-treated rats (15 micrograms/kg) that were maintaining different levels of body weight was compared. First, daily feed intakes of TCDD-treated and control rats were determined from Day 25 to 30 post-treatment. Second, weights of both groups were lowered by reducing feed intake in two successive 5-day periods to 50 and 10% of the respective ad libitum level. Third, on Days 40 to 45, both groups were refed their prereduction level of intake but reduced in proportion to the intervening loss in metabolic tissue mass. At each level of feed energy reduction, weight losses observed in the TCDD-treated and control rats were equivalent. Furthermore, although given only prerestriction amounts of feed that were indexed to their reduced metabolic body size (body wt kg 0.75), both TCDD-treated and control rats gained weight rapidly and at similar rates during the refeeding period. Thus, rats treated with a sublethal dose of TCDD displayed normal efficiency of feed utilization but did so at a subnormal level of weight. That is, just like control rats, TCDD-treated rats increased their efficiency of feed utilization (weight gain/feed intake) but only when their body weight was caused to fall below the lower weight maintenance level determined by the TCDD dose administered.(ABSTRACT TRUNCATED AT 400 WORDS)

Characterization of the wasting syndrome in rats treated with 2,3,7,8-tetrachlorodibenzo-p-dioxin

Treatment of male rats with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) causes a dose-dependent decrease in body weight, feed intake, resting and total oxygen consumption, and spontaneous motor activity. In animals treated with a nonlethal dose (5 or 15 micrograms/kg), feed intake and oxygen consumption recover within 3 weeks post-treatment to levels appropriate for the reduced weight of the animals. Rats treated with a lethal dose (50 micrograms/kg) lose weight continuously after treatment and typically die at a body weight approximately half that of age-matched, control rats. The similar dose and time dependencies for reduction of feed intake and weight suggest that hypophagia is the major factor responsible for weight loss in TCDD-treated rats. To determine if this hypophagia is a primary or secondary effect of TCDD treatment, rats whose body weights were reduced by food restriction prior to treatment (25 micrograms/kg) were studied. When allowed to feed ad libitum immediately after treatment, these animals exhibited relative hyperphagia and weight gain demonstrating that TCDD did not impair their capacity to feed. This finding suggests that the primary effect of TCDD is not on a system that controls feed intake, but rather on one that regulates body weight. It is proposed, as a heuristic model of the wasting syndrome, that TCDD treatment lowers a "set point" for regulated body weight in the rat in a dose-dependent fashion and that hypophagia serves, as a secondary response, to reduce the animal's weight to the lower regulation level determined by the dose administered.

Evaluation of the ability of d-penicillamine to protect rats against the neurotoxicity induced by zinc pyridinethione, acrylamide, 2,5-hexanedione and p-bromophenylacetylurea

Dietary exposure of rats to three different concentrations of zinc pyridinethione (ZPT; 166, 332, 498 ppm) caused delayed onset failure in a treadmill test and, at the higher concentrations (332 and 498 ppm), death. Daily treatment with d-penicillamine (d-PEN) increased the latency period for treadmill failure and lethality. Comparable levels of toxicity were achieved only after d-PEN treated rats had consumed 2-3 times more ZPT than rats not treated with d-PEN. In contrast to ZPT, administration of d-PEN did not affect the onset of treadmill failure associated with acrylamide, p-bromophenylacetylurea or 2,5-hexanedione. Thus, d-PEN provided protection which was selective for ZPT.

Prolonged survival without therapy in congenital adrenal hypoplasia

A diagnosis of congenital adrenal hypoplasia was established in a male child at 3 years of age. Although there was biochemical evidence of mineralocorticoid deficiency when he was 2 months old, no definite glucocorticoid deficiency was demonstrated. The child thrived well without replacement hormone therapy until he contracted an illness associated with vomiting. Subsequent tests confirmed the existence of both glucocorticoid and mineralocorticoid deficiencies due to adrenal hypoplasia. This case and the other reported in the literature point out that the glucocorticoid deficiency in congenital adrenal hypoplasia may become progressively more severe with time. Congenital adrenal hypoplasia may be the correct diagnosis in cases mistakenly diagnosed as acquired adrenal insufficiency.

Effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin on [3H]thymidine incorporation into rat liver deoxyribonucleic acid

The effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on [3H]thymidine incorporation into hepatic DNA was studied in rats. In non-hepatectomized male and female animals, incorporation measured at the peak of the first round of liver DNA synthesis after TCDD treatment (10 micrograms/kg) was similar to that of control animals. In contrast, the first round of [3H]thymidine incorporation after a 1/3 hepatectomy was enhanced 3-fold in TCDD-treated rats. The enhanced response to 1/3 hepatectomy was produced by doses of TCDD ranging from 1 to 30 micrograms/kg with an apparent ED50 of 5 micrograms/kg. Enhanced incorporation was observed when the 1/3 hepatectomy was performed 5-10 days after an ED50 dose and it returned to the control level after 20 days. This enhanced response was not preceded by changes in food consumption or hepatic activities of ornithine decarboxylase (ODC), tyrosine aminotransferase (TAT) or gamma glutamyl transpeptidase (GGT) when compared to respective control values. Also, the enhanced incorporation was not necessarily due to removal of 1/3 of the liver because it was also seen in TCDD-treated rats that were laparotomized. The mechanism of enhancement in laparotomized animals does not appear to involve a diminished response of the liver to the inhibitory effects of adrenal hormones on liver DNA synthesis. This was suggested by the finding that an adrenalectomy prior to the laparotomy did not block the enhanced incorporation of [3H]thymidine into hepatic DNA. The mechanism by which TCDD enhances the first round of liver DNA synthesis after a 1/3 hepatectomy or laparotomy remains to be determined.

Data on virilization and erotosexual behavior in male hypogonadotropic hypopituitarism during gonadotropin and androgen treatment

The goal of this investigation was to assess whether or not gonadotropin therapy enhanced the degree of virilization and psychosexual behavior of men with hypogonadotropic hypopituitarism. Pre- and post-gonadotropin assessments of virilization in four men indicated that gonadotropin therapy was associated with dramatic improvements in the degree of virilization that each man previously obtained on androgen only. Retrospective interview data on erotosexual behavior indicated improved erotosexual function on gonadotropin as compared to the prior androgen treatment. These data suggest that complete virilization in these men was partially gonadotropin dependent. Whether or not the behavioral benefits reported by these men represented a direct or synergistic effect of gonadotropin in the expression of erotosexual behavior or an indirect effect of improved virilization can not be answered by these data.

Enhancement of carrageenan and dextran-induced edemas by 2,3,7,8-tetrachlorodibenzo-p-dioxin and related compounds

Paw edema formation after the subplantar injection of carrageenan was enhanced in rats treated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The enhanced carrageenan response could be detected as early as 4.5 hr after TCDD; however, the magnitude of enhancement was greatest when rats were challenged with carrageenan 5 days after TCDD. In the latter case, the ED50 of TCDD in enhancing the carrageenan response was 6 micrograms/kg. TCDD also enhanced dextran-induced paw edema, which follows a time course different from that of carrageenan-induced edema and is produced by a different mechanism. The enhancement of carrageenan and dextran paw edemas was due to an increase in the edema-producing potency of the irritants and not to a change in their maximum effect. The ability of other 3-methylcholanthene-type inducers to enhance carrageenan-induced paw edema and the inability of phenobarbital-type inducers to cause the response suggest that the TCDD binding protein might be involved in edema enhancement. TCDD also enhanced carrageenan-induced pleural edema; however, the number and type of leukocytes recovered in the pleural exudate was not affected. TCDD did not alter granuloma formation produced by the subcutaneous implantation of cotton pellets, indicating that enhancement by TCDD was peculiar to edema formation and not to inflammation in general. It is suggested that TCDD may enhance carrageenan and dextran edemas by increasing the availability of mediators involved in each type of edema formation and/or by increasing the responsiveness of the vasculature to mediators.

Isolation of xanthomegnin from Penicillium viridicatum by preparative high-pressure liquid chromatography

A method was developed for the production and purification of xanthomegnin from Penicillium viridicatum (NRRL 6430) cultured on rice at 15 degrees C for 29 days. Liquid-liquid extraction followed by high-pressure liquid chromatography afforded 440 mg of crystalline xanthomegnin per kg of rice.

Remission of Cushing's syndrome during pregnancy

We present the first report of pregnancy with Cushing's syndrome due to an adrenal cortical adenoma, in which the hypercortisolemia disappeared during the third trimester of pregnancy, but recurred following the delivery of a normal male infant at 38 weeks by Cesarean section. The case is also unique because plasma ACTH levels were elevated during gestation and postpartum. Also, urinary estriol excretion was very low during the third trimester of pregnancy. The relationship of Cushing's syndrome and pregnancy are reviewed. This study points up some of the limitations of the routinely used dynamic tests of pituitary-adrenal function in Cushing's syndrome, and emphasizes the importance of various radiologic procedures in evaluation of patients with Cushing's syndrome.

Age dependence of dithiobiuret neurotoxicity in male and female rats

Weanling, juvenile and adult rats both sexes were treated with 1 mg/kg/day [14C] dithiobiuret (DTB) until they developed skeletal muscle weakness as detected by failure in a rotarod test. The latent period before the onset of weakness was longest in weanling animals of both sexes. The greater resistance of the weanlings, to DTB intoxication, could not be explained by differences in the cumulative body burden or tissue distribution of DTB and its metabolites. The sex of the animal was not a determinant of DTB toxicity. Urine and feces were the major and minor routes, respectively, for elimination of DTB and its metabolites in all animals. However, weanlings excreted relatively less 14C by the urinary route and more by the fecal route when compared to adults. These findings demonstrated the age dependence of DTB neurotoxicity in rats and show that it is not caused by differences in either the cumulative body burden or tissue distribution of DTB-derived [14C].

Dithiobiuret metabolism in the rat

Our main objective was to describe the metabolism of dithiobiuret (DTB) in the adult, male rat. Based on the thin-layer chromatographic analysis of urine from animals treated ip with 1 mg/kg of [14C] or [35S] labeled DTB, two pathways for metabolism are proposed. One pathway is reversible and involves the oxidation of DTB to thiuret and the reduction of thiuret back to DTB. The other pathway consists of the desulfuration of DTB to monothiobiuret. The liver appears to desulfurate DTB because DTB-derived [35S] was eliminated from the liver more rapidly (T1/2 = 10 hr) than [14C] (T1/2 = 15 hr). The liver was the only tissue where the elimination kinetics of [35S] and [14C] DTB were different. For all extrahepatic tissues examined and plasma, the elimination of DTB-derived [35S] paralleled that of [14C]. The T1/2 for plasma disappearance of both radiolabeled forms of DTB was approximately 10 hr and the cumulative urinary excretion of DTB-derived [35S] and [14C] was parallel and amounted to about 60% of the dose in 24 hr. DTB-derived radioactivity in urine that co-chromatographed with DTB, monothiobiuret, thiuret and sulfate was quantitated along with that of three uncharacterized metabolites. The presence of these unknown metabolites suggests that DTB metabolism is complex. The present study is the first description of the metabolic fate of DTB in the rat and serves as a starting point for determining whether DTB neurotoxicity is caused by the parent compound or a metabolite.

Heat loss and tolerance time during cold exposure in heliox atmosphere at 16 ATA

Four different types of protective clothing and three different methods of heat conservation protection were evaluated during an exposure to 4 degrees C cold in a heliox atmosphere at 150 msw. The divers using protective systems with little insulation had to quit the test after 1-2 h due to uncontrollable shivering and an extreme feeling of cold, whereas the divers using the heavily insulated clothing were able to stay in the chamber for 8-10 h. However, even with adequate protection against convective heat loss from the skin, respiratory convective heat loss will be high unless inspired gas is heated. This can be adequately done by using a combined heat-exchanger and scrubber where the heat produced by CO2 absorption is used to warm the inspired gas.

Central nervous system reactions during heliox and trimix dives to 31 ATA

Two groups of divers were compressed to 300 msw (984 fsw) with heliox (n = 3) and trimix (n = 3). Neuropsychological/neurological testing was performed repeatedly during the compression and on reaching 250 (820 fsw) and 300 msw. On the second day the trimix group was tested before and after a gas change to heliox. For the heliox group there was a marked increase in tremor and EEG slow waves, and reduction of alpha band and in hand-grip strength. For the trimix group visuomotor coordination was impaired. In the cognitive performance tests the heliox group was most impaired at 250 msw, whereas the trimix group was most impaired at 300 msw. Before the gas change to heliox the trimix group showed impaired performance in some tests. After the gas change, performance returned to predive levels, except for perceptual speed. There was an increase in tremor immediately after the gas change.

CONCLUSION

There was a marked HPNS effect during compression on heliox. This effect was not observed in the trimix group, but this group was mildly intoxicated on reaching saturation depth. The tests indicated slight narcotic effects also after 26 h, but this disappeared after the change in heliox.

17 alpha-hydroxylase deficiency in a genetic male and female sibling pair

The diagnosis of congenital adrenal hyperplasia due to a deficiency of the enzyme 17 alpha-hydroxylase was made in a genetic male and female sibling pair born of parents who were first cousins. The genetic male was a phenotypic female who presented with primary amenorrhea and mild hypertension. The genetic female exhibited absence of secondary sexual characteristics and severe hypertension. The plasma steroid data confirmed the diagnosis of 17 alpha-hydroxylase deficiency in both subjects: low 17 alpha-hydroxyprogesterone, elevated desoxycorticosterone, elevated corticosterone and elevated progesterone. These are the first case reports of 17 alpha-hydroxylase deficiency in a male-female sibling pair, and they add support to the hypothesis that this is an autosomal recessive disorder.

Testosterone secreting adrenal cortical adenomas

We report the hormonal and radiological evaluation of two cases of adrenal cortical adenomas that secreted testosterone exclusively. We discuss some of the pitfalls in the diagnosis of this lesion, and summarize the current knowledge of the characteristic hormonal features in the two cases and the 12 cases previously reported.