Logistic regression of inhalation toxicities of perchloroethylene--application in noncancer risk assessment

Unlike the impressive advancement of cancer risk assessment, the "cutoff approach" based on hazard quotient in noncancer risk assessments recommended by the EPA has crucial deficiencies. Several alternative approaches have been suggested in the literature to modify the noncancer risk characterization based on reference doses. Recent studies have indicated that the effects of perchloroethylene (PERC) on the central nervous system (CNS) is a much more sensitive noncancer endpoint than cancer which is currently the basis for deriving its public health criteria and standards. Studies indicate that 20 ppm of inhaled PERC concentration elicited adverse effects on the CNS in experimental animals and humans. However, the existing EPA oral reference dose (RfD), a noncancer toxicity parameter for PERC (0.01 mg/kg/day), is based on the induction of hepatotoxicity and increased body weight gain induced by PERC in rats. An attempt was made in this paper to examine whether logistic regression of dose-response data could be applied to assess the noncancer risks. In order to perform logistic regression the inhalation toxicity data of PERC were classified according to the severity of toxicity paradigm used in toxicity analysis. Based on the sensitive noncancer endpoints identified from severity classification, a logistic regression analysis of the data was performed and its potential applicability in noncancer risk characterization was described for workers exposure to PERC in dry-cleaning operations.

Takayasu arteritis: initial and long-term follow-up in 16 patients after percutaneous transluminal angioplasty of the descending thoracic and abdominal aorta

PURPOSE

To analyze results of percutaneous transluminal angioplasty (PTA) for stenosis of the descending thoracic and/or abdominal aorta caused by Takayasu arteritis (TA).

MATERIALS AND METHODS

Subjects were 16 patients (12 female and four male, aged 6-46 years) with symptoms of hypertension or severe bilateral lower limb claudication. Total aortography revealed stenotic lesions in the descending thoracic aorta in five, in the abdominal aorta in 10, and in both vessels in one patient. Involvement of arch vessels in four patients and of the renal artery in four patients was also noted. Double-balloon angioplasty was performed in eight patients.

RESULTS

Initial technical and clinical success was 100%. The maximum follow-up period was 52 months (mean, 21 months 2 weeks). Ankle-brachial index as determined with Doppler ultrasound improved considerably in 10 patients. Three patients had symptoms of restenosis during follow-up. Cumulative patency rate by life-table analysis was 67%.

CONCLUSION

PTA has a definite role in the management of TA in view of its procedural simplicity, cost-effectiveness, and results compared with surgical revascularization procedures.

Heterozygous missense mutation in the rhodopsin gene as a cause of congenital stationary night blindness

A number of mutations in the rhodopsin gene have been shown to cause both dominant and recessive retinitis pigmentosa. Here we describe another phenotype associated with a defect in this gene. We discovered a patient with congenital stationary night blindness who carries the missense mutation Ala292Glu. When coupled with 11-cis-retinal in vitro, Ala292Glu rhodopsin is able to activate transducin in a light-dependent manner like wild-type rhodopsin. However, without a chromophore, Ala292Glu opsin anomalously activates transducin. We speculate that the rod dysfunction in this patient is due to an abnormal, continuous activation of transducin by mutant opsin molecules in photoreceptor outer segments.

Aortoarteritis of abdominal aorta: an angiographic profile in 110 patients

The angiographic appearances in 110 patients (49 males, 61 females, age range 11-46 years, mean 27.8 years) with aortoarteritis involving the abdominal aorta and/or its branches were analysed. There were 41 aneurysms of the abdominal aorta in 37 patients and eight aneurysms of its branches in as many patients. In 50 patients, 53 obstructive lesions involved the abdominal aorta and were classified as stenoses of focal, segmental and diffuse types and total occlusions. Branch obstructions (182 lesions in 85 patients) affected in order of frequency, the renal, superior mesenteric, coeliac, iliac and the inferior mesenteric arteries. Mesenteric arterial lesions were significantly more common in males (P = 0.01). Collateral circulation through a prominent mesenteric arcade was a distinctive angiographic feature in 28 patients. Computed tomography done in four patients showed peri-adventitial thickening and layered thrombus within aneurysms in three patients, and luminal occlusion of the upper abdominal aorta in one patient. Angiographic appearances in aortoarteritis of the abdominal aorta are characteristic and sufficiently distinctive for definitive diagnosis and appropriate management.

Multiple pulmonary-artery aneurysms due to mucoid vasculopathy--angiographic and histological observations

Multiple peripheral pulmonary artery aneurysms were diagnosed by computed tomography and confirmed angiographically in a 7-year-old boy. On histological examination unusual mucoid vasculopathic changes were noted in the pulmonary artery aneurysms and pulmonary vasculature as a part of systemic vascular involvement. This case demonstrates a new association between mucoid vasculopathic changes and pulmonary aneurysms. Mucoid vasculopathy could represent one more disorder having a causative role in the etiology of intrapulmonary arterial aneurysms.

Total occlusion of iliac arteries: results of balloon angioplasty

Fifty-six occluded iliac arteries (mean length 6.1 cm; range 1-17 cm) in 50 patients were treated by percutaneous transluminal angioplasty (PTA) or laser-assisted PTA (bilateral lesions in 6 patients). Twenty-seven patients (54%) were at high risk for surgery. Patients were followed for a maximum period of 72 months (mean 23.12 months; median 20 months). The initial success rate was 78.57% for arteries and 82% for patients. Laser-assisted PTA was attempted in 11 occluded arteries (19.64%) and was successful in 4 arteries (7.14%). Conventional PTA was successful in 71.4% of arteries including all 7 arteries for which laser-assisted PTA failed (76% of patients). PTA was unsuccessful in 12 arteries (21.43%). Urokinase was used before PTA in 1 artery. The effect of PTA was evident clinically by relief of rest pain (66.66%), healing of ulcer (57%), increased claudication distance or no claudication (79%) in limbs, and objectively, by improvement in ankle/arm index (AAI) (an increase of 0.16 to 0.91) and increased exercise tolerance. Continuous improvement in AAI was observed after PTA on follow-up in 9 limbs. One patient died during follow-up. On follow-up, 3 arteries were occluded, 6 showed evidence of stenosis, and 1 showed fusiform dilatation at the PTA site. The long-term results using the life-table method determined a 76% primary patency rate and 81% secondary patency rate for 72 months. The overall patency including failures was 63%. Age of the patients (p = 0.0169) and hypertension (p = 0.0015) significantly affected the long-term patency of the artery but not the initial success. The major complications were arterial rupture in a repeat procedure in 1 artery, axillary artery thrombosis in 1, and distal thromboembolic occlusion during PTA in 4. The long-term patency rates suggest that PTA of totally occluded iliac arteries is a safe and effective procedure and provides a long-term benefit.

Arteriovenous aneurysm of the occipital artery

We report an unique case of a giant aneurysm of the occipital artery, with a venous connection to the transverse sinus via an emissary vein. Because of this connection, the term arteriovenous aneurysm is used.

Genetic heterogeneity and population structure of Gond-related tribes in the Vidarbha region of Maharashtra

Genetic heterogeneity in nine polymorphic loci is observed among Gond-related tribes in the Vidarbha region of Maharashtra. Pardhans, with their high ABO*A2 gene frequency (4.01%), low m gene frequency (57%), high P*1 gene frequency (42.7%), and high HbS trait (31.58%), differ significantly from other tribes. Per locus average heterozygosity among the studied tribes ranged from 36.24% to 40.37%, with Pardhans being more heterozygous. Analysis by FST and the empirical relationship between average allele frequencies and the ratio of within-gene to total gene diversity show that the tribes are isolated and that differentiation among them is at an early stage and approximately in conformity with expected differentiation under genetic drift. However, distances and principal components analysis reveal that Pardhans are far removed from the other tribes and from other central Dravidian tribes. Furthermore, of the various demographic parameters estimated, the high average heterozygosity in Pardhans is significantly correlated with mean marital distance (MMD), regression of MMD on wife's age, and effective population size. There is congruence between genetic and demographic data, showing that Pardhans are distinct. This conforms with Haimendorf's (1979) contention based on cultural traits that Pardhans are Gonds by historical accident and are later migrants to the Gond area from the north. The most significant and practical observation of the present study is that migration from an originally nontribal (Pardhan) to a tribal (Gond) area and admixture lead to severe disease course, differential selection pressure, and hence highly elevated HbS trait frequency.

Binary combination effects of some pharmacologically active chemicals as promoters of tumorigenesis

Identification of potential interactions in exposures either to simultaneous or sequential combinations of carcinogenic chemicals and chemicals that modify carcinogenesis poses considerable difficulties in human health risk assessments. Studies of experimental carcinogenesis over the past four decades have revealed that many pharmacologically active agents possess tumorigenesis-promoting properties. The effort to identify the possible chemical structural basis of interactions of binary combinations of carcinogenic chemicals and chemical agents that modify carcinogenesis led to the identification of a class of structurally diverse and pharmacologically active tumorigenesis promoters that are known as pharmaceuticals. The chemical class-class interactions of carcinogens and pharmaceutical agents with reported tumorigenesis-promoting properties and the possible biochemical mechanism(s) that underlie such interactions are discussed.

Histopathological evaluation of polymethyl methacrylate as an embolic agent

Polymethyl methacrylate (PMMA) microspheres were used as an embolic agent to reduce the vascularity in eight patients with intracranial vascular tumours. Post embolization angiograms showed 30-60% reduction in the vascularity of the tumours. No patient developed any neurological complications in the immediate post-embolization period. These eight patients subsequently underwent surgery for the removal of their tumours. During surgery there was minimal blood loss and a good plane of cleavage was obtained between the tumour and the adjacent brain. The surgical specimens were examined histopathologically for the effects of PMMA. PMMA microspheres, in contrast to other cyanoacrylates--isobutyl-2-cyanoacrylate (IBCA)--did not elicit either inflammatory reaction or mural angionecrosis within the wall of the embolised vessels. The histopathological studies suggest that PMMA microspheres are an inert material and can be used as an adjunct in the management of intracranial vascular tumours.

Hyperperfusion syndrome following balloon angioplasty and bypass surgery of aortic arch vessels: a report of 3 cases

Hyperperfusion syndrome is a rare complication following revascularization for severe cerebrovascular occlusive disease. We report 2 cases with milder manifestations of this syndrome in the form of unilateral headache following balloon angioplasty of brachiocephalic arteries, and 1 case with massive cerebral hemorrhage after aorto-carotid bypass surgery. The mechanism of autoregulation of cerebral blood flow and the pathophysiology of cerebral hyperperfusion are discussed. The importance of recognizing this phenomenon and possible means of preventing its occurrence are emphasized.

Syringohydromyelia: radiological evaluation of 82 patients in a developing country

A series of 82 patients presenting with syringohydromyelia and confirmed at operation were studied by conventional radiological techniques and computed tomography (CT). Cord collapse was demonstrated in 71% of the patients with wide bony canals and only 11% of patients with normal bony canals. It was most reliably shown with high resolution CT. Intrathecal CT metrizamide myelography (CTMM) failed to demonstrate contrast percolation into many cavities shown in the plain scans. Obliteration of the subarachnoid space at C1-2 levels appreciated in the plain scans strongly indicated coexisting tonsillar herniation, making CTMM unnecessary. In almost all patients, CTMM was found to be non-contributory if the high resolution plain CT scan failed to reveal cord cavitation.

Obstruction of the infrarenal portion of the abdominal aorta: results of treatment with balloon angioplasty

Our experience in the treatment of stenoses of the infrarenal portion of the abdominal aorta with balloon angioplasty in 27 patients is reported. Clinical findings were lower limb claudication (all patients), impotence (eight patients), and blue-toe syndrome (two patients). The underlying disease was atherosclerosis in 24 patients and nonspecific aortoarteritis in three patients. Dilatation was successful in all patients. Embolic occlusions of the left common iliac artery (one patient) and left superficial femoral artery (one patient) were the only major complications. Claudication in the affected limb continued in the first patient; the second died when diagnostic angiography, performed 3 months after angioplasty, caused a severe atheroembolus. Of the other 25 patients, nine of the 10 followed up for 13-48 months and all seven followed up for 3-8 months were free of symptoms. Six of eight patients with sexual dysfunction had normal function after angioplasty. Seven patients still awaited follow-up and one was lost to follow-up. Our experience suggests that balloon angioplasty is an effective treatment of stenoses of the infrarenal portion of the abdominal aorta.

Binary effects of carcinogens and tumor promoters--a preliminary chemical structural analysis of BCIDB and PCIDB

Identification of potential interactions in exposures, either to simultaneous or sequential combinations of carcinogenic chemicals and mixtures of carcinogen and carcinogenesis-modifying chemical agents, pose formidable difficulties in human health risk assessments. Studies over the past four decades have revealed synergistic interactions among various classes of carcinogenic chemicals. An earlier effort to identify a possible chemical structural basis of interaction of binary combinations of carcinogens led to the development of Binary Carcinogen Interaction Data Base (BCIDB). A recent endeavor to identify a structural basis of interactions of carcinogens and carcinogenesis modifying chemical agents resulted in Promoter-Carcinogen Interaction Data Base (PCIDB). An attempt will be made in this report to briefly discuss chemical class-class interaction and initiator-target organ orientation as recorded in BCIDB and PCIDB.

Disappearance of a cerebral aneurysm--an unusual angiographic event

Spontaneous thrombosis of cerebral aneurysms demonstrated by angiography is infrequent. This article describes angiographically documented spontaneous thrombosis of an intracranial aneurysm at the posterior cerebral-posterior communicating artery junction in a 40-year-old woman. The initial angiogram done on 16th day after an episode of subarachnoid haemorrhage showed a medium sized aneurysm. Subsequent angiograms done on 30th, 40th and 60th day failed to demonstrate the aneurysm. The factors leading to this rare event remain obscure.

Sickle cell hemoglobin, beta-thalassemia and G6PD deficiency in tribes of Maharashtra, India

The prevalence of sickle cell hemoglobin (HbS), beta-thalassemia trait and G6PD deficiency are reported in some important Gond related endogamous tribes in Maharashtra, India. The HbS gene frequency varies from 0.0530 to 0.1805, the beta-thal gene from 0 to 0.0283 and Gd- gene from 0.0189 to 0.1120. The Pardhan tribe has been identified as a high risk group for sickle cell diseases. Statistically significant differences are observed between tribes.

Aneurysmal form of aortoarteritis (Takayasu's disease): analysis of thirty cases

The clinical and radiological features, and outcome of 30 patients including 22 females, with the aneurysmal form of aortoarteritis were analysed. The average age at diagnosis was 27.4 +/- 7.2 years. Features which indicated the diagnosis of aneurysmal aortoarteritis included young age, female sex, characteristic location, associated stenotic lesions and the presence of multiple aneurysms. There were 41 fusiform and 18 saccular aneurysms, mostly located in the descending aorta. Diffuse dilatation (n = 24) was seen mainly in the ascending aorta. Two patients had dissecting aneurysms, while one patient had an aneurysm of the left main coronary artery. Both these lesions are rare in aortoarteritis. The aneurysmal form was associated with a higher incidence of aortic incompetence (P less than 0.01) and elevated ESR (P less than 0.001) as compared to the more common non-aneurysmal form. The average follow-up period was 59.7 (+/- 48.1) months. The event-free survival rate was 82.9% at 5 years, similar to that seen in the non-aneurysmal form. These data should be useful to the clinician in the diagnosis and management of the aneurysmal form of aortoarteritis.

Prevalence of HBsAg carriers among some tribes of Madhya Pradesh

Prevalence of HBsAg was determined in 1314 sera obtained from 11 different tribal populations of five districts of Madhya Pradesh. Reversed passive haemagglutination assay was used for screening showed a HBsAg carrier rate of 2.99 to 21.54 per cent among the various tribes. Significant regional variation was also observed.

Embolization of large saccular aneurysms with Gianturco coils

In five patients embolization of large saccular aneurysms involving the popliteal artery, common carotid artery, arch of the aorta, and abdominal aorta was performed with custom-designed spring coils. Surgery was attempted before embolization for the aneurysm involving the popliteal artery. The other aneurysms were considered nonresectable due to their critical location. Although maximal packing of the aneurysmal sac was attempted, delayed follow-up angiography revealed displacement of the coils away from the parent vessel as well as further expansion of the residual aneurysmal sac. In these cases complete embolization of the aneurysmal sac was not possible without obstructing the parent artery.

Interactions of cryptosin with mammalian cardiac beta-adrenoceptors

Cryptosin - a new cardenolide from the leaves of Cryptolepis buchanani R & S was found to be a potent positive inotropic agent. In experiments with dog heart ex vivo, the rise in the cardiac rate associated with an increase in dP/dtmax and left ventricular pressure (LVP) correlated with changes in the beta-adrenoceptor densities as measured by the binding of 3H-Dihydroalprenolol (DHA). A significant change in the beta-adrenoceptor densities was observed when cryptosin was incubated with guinea pig and dog heart sarcolemmal membranes in vitro. Analysis of the binding of 3H-DHA in post-cryptosin treated membranes indicated a non-specific type of interaction of cryptosin with mammalian cardiac beta-adrenoceptors.

Interactions of cryptosin with mammalian cardiac dihydropyridine-specific calcium channels

Cryptosin -a new cardenolide was found to be a potent inhibitor of cardiac Na+ and K+ dependent Adenosinetri-phosphatase (7). In experiments with dog heart ex vivo, development of inotropic and toxic effect correlated with changes in the cardiac dihydropyridine-specific calcium channels as measured by the binding of 3[H]PN 200-110. A significant change in the PN 200-110 binding was observed when guinea pig and dog heart sarcolemmal membranes were pre-incubated with cryptosin in vitro. Binding analysis of 3[H]PN 200-110 (Isradipine) - -a 1,4-dihydropyridine analog with very specific calcium channel binding properties - in both in vitro and ex vivo studies were consistent and indicated a non-specific type of interaction of cryptosin with mammalian cardiac 1,4-dihydropyridine-specific calcium channels.

Corpus callosum lipoma with frontal encephalocele

Computed tomographic and plain X-ray observations in a patient with corpus callosum lipoma associated with frontal encephalocele are reported. The rarity of the lesion and the specific diagnostic criteria on CT are emphasised.

Vitamin and provitamin A levels in epithelial cancers: a preliminary study

A major physiological role of retinoids is the regulation of epithelial and epidermal cell differentiation. A total of 285 patients with clinically and histopathologically confirmed diagnosis of various carcinomas (untreated) were selected for the study. The control values of serum beta-carotene and vitamin A levels were established from 50 subjects free of any known pathology. The controls were matched for age and sex. The mean serum levels of beta-carotene and vitamin A have shown a significant difference (p less than 0.001) in all the cancers compared with the controls. In cancer of the oral cavity, the males showed significantly lower levels (p less than 0.01) compared with their female counterparts. In cancer of the lung, however, the mean serum levels of beta-carotene and vitamin A were higher in males compared with females (p less than 0.02). Our results suggest a possible association between vitamin A and epithelial cancer, but whether the deficiency is the cause of the disease or if it is due to the tumor remains unknown.