Duplication of the 15q11-13 region in a patient with autism, epilepsy and ataxia

Various developmental abnormalities can give rise to the clinical syndrome of autism, and some are due to chromosomal anomalies. One syndrome has been identified in which behavioural disorder is associated with the clinical features of epilepsy and ataxia, and with the chromosomal anomaly of an extra marker chromosome containing a duplication of 15q11-13. The authors report a boy with autism, epilepsy, ataxia and an interstitial duplication of 15q, in whom molecular analysis reveals duplication of the GABRA5 and GABRB3 genes on the maternally derived chromosome.

Disposition of MK-852, a fibrinogen receptor antagonist, in rats and dogs

MK-852, an antagonist of the platelet fibrinogen receptor GPIIb/IIIa, is the cyclic disulfide N-acetyl-cys-asn-(5,5-dimethyl-4-thiazolidine-carbonyl)- (4-aminomethyl-phe)-gly-asp-cys, monoacetate (all L-amino acids). Radiolabeled MK-852 was synthesized with either a 3H label in the N-acetyl group of the cystine residue or a 14C label in the aminomethyl group. Plasma concentrations of unchanged MK-852 in five rats declined with a mean terminal half-life of 0.92 hr after a 2.5 mg/kg i.v. dose of MK-852; plasma clearance and Vd were 23.1 ml/min/kg and 1.81 liters/kg, respectively. More label was excreted in urine (74-76%) than in feces (7-15%) when either [3H]MK-852 or [14C]MK-852 was given intravenously to groups of four rats (2.5 mg/kg). High concentrations of 3H in rat kidney were consistent with high renal clearance of MK-852, and MK-852 accounted for virtually all of the urinary 3H (and 14C) label. Following a 0.6 mg/kg i.v. dose, the half-life, plasma clearance, and Vd of MK-852 in four dogs were 0.84 hr, 3.93 ml/min/kg, and 0.28 liters/kg, respectively. In dogs, the excretion patterns of radioactivity were similar to those of rats, except that 14C urinary recoveries (79%) were higher than 3H (63%). Unchanged MK-852 represented essentially all of the urinary 3H label. Fractionation of dog 14C urinary radioactivity yielded one major and several minor polar labeled species. The major species was unchanged [14C]MK-852 (quantitated by radioimmunoassay as approximately 80% of the label).(ABSTRACT TRUNCATED AT 250 WORDS)

A male with a de novo translocation involving loss of 15q11q13 material and Prader-Willi syndrome

A male proband is described who carries a de novo translocation between chromosomes Y and 15 associated with Prader-Willi syndrome. In situ hybridisation and molecular studies were used to show loss of the paternally derived 15q11q13 region in the translocated chromosome. Lack of further symptoms indicate that this region was lost with no apparent deletion of the Y chromosome.

Metabolic disposition of simvastatin in patients with T-tube drainage

A study to investigate the disposition and biliary excretion of simvastatin (SV) was conducted in four cholecystectomy patients with T-tube drainage. Each patient received a single oral dose of 100 mg of [14C]SV (20 microCi). Of the 14C-labeled dose, approximately 35% was excreted in urine, 25% in bile, and 20% in feces. Thus, at least 60% of the oral dose was absorbed from the gastrointestinal tract. Of the AUC for radioactivity in plasma, 13% was contributed by the HMG-CoA reductase inhibitors. In addition, only 2% of the 14C-dose was eliminated in urine as HMG-CoA reductase inhibitors. Thus, most of the SV-related compounds in plasma and urine have little or no HMG-CoA reductase inhibitory activity. The same is probably true for these compounds in bile. Two major active metabolites were present in the bile. Based on HPLC and MS/MS data, they were identified as 6' beta-COOH-SVA and 6'-OH-SVA. In general, the majority of the radioactivity in the bile and urine was excreted within 24 hr postdose. Of the radioactivity excreted in the 0- to 24-hr bile, on average, approximately 30% was contributed by 6' beta-COOH-SVA and 6'-OH-SVA. These two metabolites accounted for the majority of HMG-CoA reductase inhibitory activity in the bile. Little or SV or no SVA was present in the bile.

In vivo and in vitro metabolism studies on a class III antiarrhythmic agent

The metabolism of L-691,121 (I), a class III antiarrhythmic agent, was studied in vivo in rats and dogs and in vitro by using liver S9 or slices from these species and humans. After oral doses of [14C]I to rats (5 mg/kg) and dogs (1 mg/kg), urinary recoveries of label were, respectively, 6% and 28%. Biliary excretion (0-24 hr) accounted for 68% of a 5 mg/kg, po dose in rats and 19% of a 10 mg/kg dose, po in dogs. Metabolites were identified by application of FAB/MS, NMR, and diode-array UV spectroscopy. The major dog metabolites were the secondary alcohol (II) produced by carbonyl reduction and its glucuronide conjugate (III). It was estimated that II and III represented 24 and 36%, respectively, of the dog biliary radioactivity. After a 50 mg/kg dose of I, II represented approximately 50% of the dog urinary label. A minor metabolite (IV) in dog urine was produced by reduction and loss of N-substitution. There were species differences in that, relative to dogs, II represented a much smaller fraction of the excreted dose in rats and there was no evidence for excretion of III in rats. N-Dealkylated I (V) was excreted, along with IV in rat bile. Dog liver slices and S9 fractions were most efficient (relative to human and rat liver tissues) at reducing I to II. Metabolic reduction of I to II was highly stereoselective and yielded the (-)-antipode as determined by chiral chromatography.

Mesenteric vasoconstriction in cardiogenic shock in pigs

The quantitative impact of mesenteric vasoconstriction on the systemic hemodynamic response to cardiogenic shock induced by pericardial tamponade was evaluated. Graded increases in pericardial pressure produced corresponding decreases in cardiac output to 44% +/- 2% and arterial pressure to 64% +/- 3% of baseline and increases in total peripheral vascular resistance to 131% +/- 4% of baseline. Total mesenteric blood flow decreased disproportionately, to 28% +/- 3% of baseline, because of a disproportionate increase in mesenteric vascular resistance to 223% +/- 6% of baseline. Nonmesenteric vascular resistance increased only to 119% +/- 4% of baseline. Thus mesenteric vasoconstriction accounted for 42% of the increase in total peripheral resistance. Prior blockade of the renin-angiotensin axis ablated this response and eliminated the mesenteric contribution to systemic vascular resistance, while confirmed blockade of the alpha-adrenergic system or vasopressin system had no effect. Without shock, central intravenous infusions of angiotensin II (but not norepinephrine or vasopressin) closely mimicked this selective vasoconstriction. Angiotensin-mediated selective mesenteric vasoconstriction accounts for more than 40% of the overall increase in systemic vascular resistance in cardiogenic shock.

Studies on the metabolic inversion of the 6'chiral center of simvastatin

In two simvastatin (SV) metabolites the 6' alpha-methyl of SV is oxidized to either 6' beta-CH2OH (I) or 6' beta-COOH (II). A possible intermediate is 6' exomethylene SV (III). When Sprague Dawley rats received an i.v. dose of [14C] III (1 mg/kg) metabolite II was excreted in bile. When dogs received an i.v. dose of [14C] III together with either [3H] SV (1 mg/kg) or its hydroxy acid form, [( 3H] SVA) (10 mg/kg), both 3H and 14C I and II were excreted in bile. These results strongly indicate that I and II are secondary metabolites of SV formed from III perhaps via a common aldehyde intermediate.

Single-dose pharmacokinetics of 14C-lovastatin in chronic renal failure

An open study on the pharmacokinetics of lovastatin was conducted in six patients with chronic renal failure (mean creatinine clearance, 0.40 ml/sec; range, 0.20 to 0.65 ml/sec) and seven healthy subjects. Plasma levels of 3-hydroxy-3-methylglutaryl-coenzyme reductase inhibitory activity (total and active) and total radioactivity were determined over 168 hours after a single dose of 80 mg 14C-lovastatin. The mean area under the plasma concentration-time curve for active inhibitors were 606 +/- 346 and 282 +/- 138 ngEq.hr/ml (p = 0.04) in patients and control subjects, respectively. Total inhibitors in plasma and total radioactivity were similarly elevated in patients with chronic renal failure. Results indicate that patients with severe renal dysfunction have altered elimination kinetics of lovastatin. Current ongoing clinical studies in patients with renal dysfunction will allow better assessment of the pharmacodynamic meaning of our observations.

Molecular biology of circulatory shock. Part II. Expression of four groups of hepatic genes is enhanced after resuscitation from cardiogenic shock

Despite an initially successful resuscitation from circulatory shock, multiple organ failure (MOF) develops in some patients. The marked biochemical alterations associated with shock and MOF include clinically important changes in gene expression, such as altered rates of albumin and procoagulant synthesis. To characterize the MOF-associated changes at the cellular level, sequential liver biopsies were obtained from a swine model of cardiogenic shock associated with MOF. Preshock and postresuscitation biopsies were used not only to create a complementary DNA (cDNA) library but also to screen, to confirm, and, in nine out of 12 cases, to specifically identify genes whose expression is enhanced at least fivefold after resuscitation. The twelve genes thus characterized can be separated according to function into distinct groups, including the acute-phase genes and the heat-shock genes. Expression of acute-phase genes is liver specific and is essential for systemic homeostasis; heat-shock gene expression is generic to all cells and important for intracellular homeostasis.

In vitro and in vivo biotransformation of simvastatin, an inhibitor of HMG CoA reductase

Simvastatin (SV), an analog of lovastatin, is the lactone form of 1', 2', 6', 7', 8', 8a'-hexahydro-3,5-dihydroxy-2', 6'-dimethyl-8' (2", 2"-dimethyl-1"-oxobutoxy)-1'-naphthalene-heptanoic acid (SVA) which lowers plasma cholesterol by inhibiting 3-hydroxy-3-methylglutaryl-CoA reductase. SV but not its corresponding hydroxy acid form SVA underwent microsomal metabolism. Major in vitro metabolites were 6'-OH-SV (I) and 3"-OH-SV (III) formed by allylic and aliphatic hydroxylation, respectively, and 6'-exomethylene-SV (IV) formed by dehydrogenation. In rats, dogs, and humans, biliary excretion is the major route of elimination. Biliary metabolites (as both hydroxy acids and lactones) also included 6'-CH2OH-SV (V) and 6'-COOH-SV (VI) in both of which the 6'-chiral center had been inverted. High levels of esterase in rodent plasma favored the formation of SVA from SV. The formation of 1', 2', 6', 7', 8', 8a'-hexahydro-2', 6'-dimethyl-8'-(2",2"-dimethyl-1-oxobutoxy)-1'-naphthalene-pentano ic acid (VII) only in rodents represented a species difference in the metabolism of SV. It is proposed that VII is formed by beta-oxidation pathways of fatty acid intermediary metabolism. Several metabolites resulting from microsomal oxidation (after subsequent conversion from lactones to hydroxy acids) are effective inhibitors of 3-hydroxy-3-methylglutaryl-CoA reductase and may contribute to the cholesterol lowering effect of SV. Qualitatively, the metabolism of SV closely resembles that of lovastatin.

Metabolic disposition studies on simvastatin, a cholesterol-lowering prodrug

The biosynthesis of cholesterol is mainly regulated by 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase. Because the liver is the major site of cholesterol synthesis, it is the primary target of the class of drugs known as HMG-CoA reductase inhibitors. Simvastatin (SV) is a lactone prodrug which undergoes reversible metabolism. In the hydroxy acid form (SVA) it is a potent inhibitor of HMG-CoA reductase. SV is well absorbed by rats, dogs, and humans. After an oral dose of SV, tissue distribution studies were consistent with high hepatic extraction of SV and relatively poor tissue penetration of SVA. The majority of a radioactive dose of SV is eliminated in bile. A high portal/systemic gradient for 6'-OH-SVA, an active biliary metabolite, suggests its probable reentry and indicates potential for prolongation of HMG-CoA reductase inhibition. AUC comparisons in dogs after simultaneous iv (3H) and intraportal (14C) infusions indicate that hepatic extraction is high with only 8% of SV reaching the systemic circulation unchanged. Approximately 98% and 96% of SV was bound to human and dog plasma protein, respectively. The physiological disposition of SV in dog appears to be a suitable paradigm for man. Because of its high hepatic extraction SV should be both specific and selective with respect to the inhibition of HMG-CoA reductase.

The physiological disposition of lovastatin

Lovastatin is a pro-drug lactone whose open chain beta-hydroxy-acid (HA) is a potent inhibitor of hydroxymethylglutaryl-CoA-reductase and thus of cholesterol synthesis. Because the liver is the major site of cholesterolgenesis, it is the principal target organ for agents of this class. In animals, lovastatin is not as well absorbed as HA given per se, but that fraction that is absorbed reaches the portal circulation largely unchanged and is more efficiently extracted by the liver, after which it is reversibly biotransformed to HA and irreversibly to other enzymatically active products. These, like HA, maintain high hepatic gradients relative to all tissues examined. The minimal systemic burden for HA is attributable in part to the metabolic equilibrium, lovastatin in equilibrium HA, the opposing reactions for which appear to be present in most tissues. Excretion is very largely biliary in all species. Detailed comparisons of absorption, distribution, metabolism, and excretion profiles presented here and elsewhere indicate dogs to be the most appropriate paradigm for humans for study of lovastatin disposition.

Botulinum toxin therapy for squint

Four hundred and five patients have been treated with injections of Botulinum neurotoxin A to extraocular muscles in the Botulinum Toxin Clinic at Moorfields Eye Hospital from November 1982 until the present. The indications and outcome of therapy are described and discussed.

The diagnosis and surgical management of acquired bilateral superior oblique palsy

Thirty-four patients with surgically treated bilateral superior oblique palsy are presented. The patients are divided into three groups: Symmetrical palsies, Asymmetrical palsies, A group in whom the bilaterality was initially masked. Bilaterality should be suspected in all cases of traumatic IVth nerve paresis, and particularly in cases with a large 'V' pattern, excyclo deviation of more than 10 degrees on down-gaze and when right hypertropia switches to left hypertropia on lateral down-gaze. Bilateral Harada-Ito procedures alone 'cured' 11 of 17 patients (65 per cent) in groups 1 and 2, and is the operation of choice in acute bilateral superior oblique palsy. Cyclo deviation was reduced by a mean of 5.5 degrees in the primary position and by 6-10 degrees in down-gaze. Patients initially managed with other surgery had a more complicated surgical course and required more operations. Seven patients who initially demonstrated only gross fusion recovered good fusion after Harada-Ito surgery.

Retinal detachment following Nd:YAG posterior capsulotomy

Five hundred and eighty-two patients who underwent Nd:YAG laser posterior capsulotomy at Moorfields Eye Hospital were reviewed retrospectively. Twelve patients (2 per cent), nine of whom were previously myopic, subsequently developed rhegmatogenous retinal detachment. Comparison with other studies suggests there is no greater risk of retinal detachment associated with Nd:YAG laser capsulotomy than with surgical discission. The relevance of the damage mechanisms of Nd:YAG lasers are discussed.

Aphakic retinal detachment

A study of 132 cases of aphakic retinal detachment (ARD) following mainly intracapsular cataract surgery has been made. Forty-nine cases (37%) were found to have vitreous incarcerated into the cataract section out of a total of 54 (41%) cases who had suffered a vitreous complication during cataract surgery. A study of the characteristics of ARD reveals that those cases having had a vitreous complication in the management of their cataracts are more likely to develop detachment within three months than those not suffering from such a complication. The occurrence of these early post-extraction retinal detachments is not influenced by the presence of underlying axial myopia. When we compared ARD in patients whose cataract extractions had been complicated by vitreous incarceration with those ARDs following uncomplicated cataract surgery, we found that the characteristics of the detachments were very similar. Thus distribution of underlying myopia, extent of detachment, length of time of detachment, and multiplicity and type of retinal holes were generally similar. However, ARD following complicated cataract surgery is more likely to suffer from periretinal fibrosis. The findings confirmed the risk of ARD following complicated intracapsular cataract surgery and support the tendency to perform the extracapsular operation.

Carnitine and glucuronic acid conjugates of pivalic acid

The [1-14C]pivaloyloxyethyl ester of methyldopa administered to man and cynomolgus monkeys resulted in the elimination in the urine of 14C-pivalic acid metabolites. Pivaloyl glucuronide and pivaloyl carnitine were identified as the major radioactive urinary metabolites in monkey urine and human urine, respectively. N.m.r. analysis indicated that pivaloyl carnitine had a cyclic structure. Although the role of carnitine is in the transport of fatty acids across mitochondrial membranes, it may also function in the conjugation of carboxylic acid xenobiotics in humans.

Sensitive high-performance liquid chromatographic assay using electrochemical detection for a novel prodrug ester of methyldopa, pivaloyloxyethyl 3-(3,4-dihydroxyphenyl)-2-methylalaninate, in plasma and urine

The pivaloyloxyethyl ester of methyldopa is an antihypertensive prodrug possessing improved bioavailability properties over methyldopa. A sensitive cation-exchange, high-performance liquid chromatographic assay using electrochemical detection has been developed for the ester in plasma and urine in order to determine the extent of its hydrolysis after oral administration. The chromatographic conditions involve two Altex Partisil 10 SCX columns (25 cm X 4.6 mm) in series; a mobile phase consisting of methanol, potassium phosphate buffer, pH 3.0, and EDTA disodium dihydrate; and an electrochemical detector set at 0.5 V. The pivaloyloxyethyl ester in plasma or urine is extracted into ethyl acetate, back-extracted into 0.1 M sulfuric acid, and analyzed directly by high-performance liquid chromatography. For urine, the ethyl acetate extract is washed with a buffer (pH 8.0) prior to the back-extraction step. The assay gives a linear response over the concentration range of 10-160 ng/ml in plasma and 20-400 ng/ml in urine.

Metabolism of methyldopa in man after oral administration of the pivaloyloxyethyl ester

In a crossover study, the pivaloyloxyethyl ester (POE) of methyldopa, labeled either with 3H in the methyldopa moiety or 14C in the pivalic acid moiety, was administered orally to four volunteers in 1000-mg single doses (equivalent to 500 mg of methyldopa). The majority (93%) of either the 3H- or 14C-labeled dose was excreted in the urine. Methyldopa, which was assayed by a fluorometric technique, peaked (approximately 6 micrograms/ml) at 1 hr in the plasma. Forty-five per cent of the dose was excreted as methyldopa as opposed to 18% normally seen after oral methyldopa dosages. Intact POE was absent in the urine of three volunteers and present in only trace amounts in urine from a fourth volunteer. Thus, the oral dose of POE was well absorbed and rapidly hydrolyzed to methyldopa. After oral administration of methyldopa, methyldopa sulfate is the principal urinary metabolite in man. However, after administration of POE, a relatively small fraction (13%) of the dose was excreted as methyldopa sulfate. The major urinary metabolite of POE, other than methyldopa, was 3-OCH3 methyldopa. Methyldopamine was a minor metabolite. It was concluded that a shift from sulfation to methylation occurred in the metabolic profile of methyldopa when it was administered as POE and that the metabolites of POE (including conjugated pivalic acid) were rapidly eliminated from the body.