Cloning of Drosophila MCM homologs and analysis of their requirement during embryogenesis

Modification of blood flow by endothelin-1 (ET-1) was examined in the s.c. HSN fibrosarcoma and compared to normal tissues of anaesthetised CBH/CBi rats. The ET receptor subtypes involved in the response were investigated using the ET(A) and ET(B) receptor antagonists BQ-610 and BQ-788, respectively. Blood flow and vascular resistance were determined using the uptake of radiolabelled iodo-antipyrine (125I-IAP). BQ-610 or BQ-788 was infused for 30 min prior to blood flow determination. ET-1 was administered 15 min into the infusion time. BQ-610 and BQ-788 infused alone did not modify any vascular parameters. Tumour blood flow increased slightly following ET-1, contrasting with most normal tissues, in which blood flow was reduced. Vascular resistance increased in all tissues, including the tumour. Neither antagonist significantly modified the ET-1-induced changes in tumour blood flow or vascular resistance, whereas in the majority of normal tissues BQ-610 attenuated and BQ-788 potentiated the vascular resonse to ET-1. Our results show that the HSN tumour vasculature is only weakly responsive to ET- 1 and antagonism of its effects by BQ-610 and BQ-788. This contrasts with the majority of normal tissues, in which ET- 1 induces an intense vasoconstriction.     

Future increase of the incidence of mesothelioma due to occupational exposure to asbestos in the past

OBJECTIVE: To estimate the future course of mesothelioma mortality as a result of occupational exposure to asbestos in the past. DESIGN: Cohort age model. SETTING: Department of Public Health, Erasmus University Rotterdam, the Netherlands. METHODS: A cohort age model was developed, based upon age-specific rates of pleural mesothelioma mortality during 1969-1994. This model was linked to the future trend in mortality among Dutch men as projected by the Central Bureau for Statistics in order to predict the future course of mesothelioma mortality in the period 1995-2030. RESULTS: In the next 35 years about 20,000 cases of pleural mesothelioma among men are expected. The projection results in a peak of annual male mesothelioma deaths of approximately 700 in about the year 2018. After 2020 the annual mortality will rapidly decline to about 450 cases in 2030. It is expected that this rapid decline will continue after 2030. In the 1943-1947 birth cohort pleural mesothelioma may account for 0.87% of all deaths. Exposure to asbestos at work largely explains this particular mortality pattern. CONCLUSION: Exposure to asbestos at work has created an important public health problem among Dutch men.     

Increased red cell sodium lithium countertransport activity, total exchangeable sodium, and hormonal control of sodium balance in normoalbuminuric type 1 diabetes

The relationship between erythrocyte sodium lithium countertransport activity (SLC), total exchangeable sodium (NaE), and hormonal control of renal function was examined in 40 normotensive, normoalbuminuric, non-neuropathic Type 1 diabetic subjects, of whom 8 had elevated SLC (> 0.40 mmol Li h-1l-1 rbc). Eleven health controls with normal SLC, who were of comparable age, body mass, and blood pressure were also studied. By contrast with healthy controls, SLC in Type 1 diabetes was not associated with plasma renin activity (PRA), aldosterone, systolic blood pressure or lean body mass. SLC was also unrelated to atrial natriuretic peptide (ANP) (Type 1 diabetes only) and NaE. NaE was not correlated with any other variables. The relationships between PRA and aldosterone in healthy controls were retained in Type 1 diabetes (R2 0.37 supine, p = 0.00001, and 0.27 ambulant, p = 0.0005), as were respective direct and inverse relations between vasopressin and ANP and both PRA (rs 0.54 to 0.57, rs -0.43 to -0.53), and aldosterone (rs 0.78 to 0.80, rs -0.71 to -0.80). Fasting free serum insulin and vasopressin were both inversely related to ANP (rs -0.91 and -0.71, respectively). In the absence of autonomic dysfunction, hypertension or early nephropathy in Type 1 diabetes, increased SLC or exchangeable sodium were unrelated to each other or with hormonal control of sodium balance, but the homeostatic factors controlling hormonal interaction appear to be maintained. The interaction between insulin and hormonal control of sodium and water balance may be modified by circulating free insulin concentrations.     

6-bit and 8-bit digital radiography for detecting simulated periodontal lesions

Considerable controversy exists in the orthopedic and neurosurgical literature over the true incidence and nature of spinal deformity after multiple-level cervical laminectomy in children. Eighty-nine patients with a mean radiographic follow up of 5.1 years (range 2-9 years) were reviewed. Mean age at surgery was 5.7 years (range 1 month-18 years). Most common diagnoses were Arnold-Chiari malformation, syringomyelia, or both (81%). Significant deformity developed in 46 patients (53%), with 33 developing a mean kyphosis of 30 degrees (range 5-105 degrees) and 13 developing a mean hyperlordosis of 62 degrees (range 40-95 degrees). Peak age at surgery of 10.5 years correlated weakly (P = 0.08) with the development of kyphosis. The development of hyperlordosis was strongly correlated (P = 0.01) with a peak age at surgery of 4.2 years. There was no correlation between diagnosis, sex, location, or number of levels decompressed and the subsequent development of deformity.     

Ah receptor binding properties of indole carbinols and induction of hepatic estradiol hydroxylation

The effect of route of administration on the ability of indole-3-carbinol (13C), an anticarcinogen present in cruciferous vegetables, to induce estradiol 2-hydroxylase (EH) in female rat liver microsomes was investigated and compared to that of its main gastric conversion product, 3,3'-diindolylmethane (DIM). This dimer was more potent than 13C after either oral or intraperitoneal administration and was also a better in vitro inhibitor of EH in control and 13C-induced hepatic microsomes. The induction of both CYP1A1 and 1A2 in about equal amounts by 13C and DIM as well as of CYP2B1/2 was demonstrated using monoclonal antibodies. DIM, isosafrole, beta-naphthoflavone, 3-methylcholanthrene and naringenin added in vitro inhibited EH strongly in induced microsomes but gestodene was a better inhibitor of estrogen 2-hydroxylation in liver microsomes from untreated female rats. The binding affinities of 13C and DIM to the Ah receptor were compared to that of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) by competition studies, and the IC50 values were shown to be 2.0 x 10(-9) M, 5.0 x 10(-5) M and 2.3 x 10(-3) M for TCDD, DIM and 13C, respectively. The ability of 13C or DIM to cause in vitro transformation of the Ah receptor to a form able to bind to the dioxin-responsive element-3 (DRE3) was compared to that of TCDD and shown to parallel their abilities to compete for binding of [3H]TCDD to the Ah receptor. These experiments confirm and extend the proposals that dietary indoles induce specific cytochrome P450s in rat liver by a mechanism possibly involving the Ah receptor. The induced monooxygenases, in turn, increase the synthesis of 2-hydroxylated estrogens in the competing pathways of 2- and 16 alpha-hydroxylation which decreases the levels of 16 alpha-hydroxyestrone able to form stable covalent adducts with proteins including the estrogen receptor. Such steroid-protein interaction has been correlated with mammary carcinogenesis.     

Catalytic mechanism of Kdo8P synthase: transient kinetic studies and evaluation of a putative reaction intermediate

The mechanistic pathway for the reaction catalyzed by Kdo8P synthase has been investigated, and the cyclic bisphosphate 2 has been examined as a putative reaction intermediate. Two parallel approaches were used: (1) chemical synthesis of 2 and evaluation as an alternate substrate for the enzyme and (2) transient kinetic studies using rapid chemical quench methodology to provide direct observation and characterization of putative intermediate(s) during enzyme catalysis. The putative cyclic bisphosphate intermediate 2, possessing the stereochemistry of the beta-pyranose form, was synthesized and evaluated as a substrate and as an inhibitor of Kdo8P synthase. The substrate activity was examined by monitoring the release of anomeric phosphate over time using proton-decoupled 31P NMR spectroscopy. A very similar time course for the formation of inorganic phosphate was found in each experiment and the corresponding control experiment; i.e., no enzyme-catalyzed acceleration in the anomeric phosphate hydrolysis was detected. It was found however that 2 binds to the enzyme and is a competitive inhibitor with respect to phosphoenolpyruvate binding, having a Ki value of 35 microM. In a parallel study, we have performed single-turnover rapid chemical quench experiments to examine both the forward and reverse directions to identify a putative enzyme intermediate(s). Our results clearly demonstrate that the cyclic bisphosphate intermediate 2 does not accumulate under single-enzyme turnover conditions. This observation, coupled with the results obtained through the evaluation of synthetic 2 as a substrate, strongly suggests that the Kdo8P synthase catalytic pathway does not involve the formation of 2 as a reaction intermediate. Taken together, these combined results support the original hypothesis [Hedstrom, L., and Abeles, R. H. (1988) Biochem. Biophys. Res. Commun. 157, 816-820], which suggests a reaction pathway involving an acyclic bisphosphate intermediate 1.     

Conversational repair in schizophrenic and normal children

OBJECTIVE: Children acquire the skills to monitor the adequacy of their spoken message and to self-initiate repair strategies that modify the message during early, middle, and late childhood. To characterize further the communication deficits of childhood-onset schizophrenia, this study compared self-initiated repair strategies in schizophrenic and normal children and their relationship with formal thought disorder, discourse deficits, and distractibility. METHOD: Measures of self-initiated repair, formal thought disorder, and cohesion were coded in 32 schizophrenic and 47 normal children, aged 5.6 to 12.4 years, from speech samples elicited with the Story Game. RESULTS: The schizophrenic children used some repair strategies (false starts, fillers, referential revision) more infrequently than the normal children. Within the schizophrenic group, the children who were receiving neuroleptic medication underutilized repair and had more discourse deficits than the unmedicated patients. Loose associations and distractibility were associated with increased use of false starts but not fillers. CONCLUSIONS: In addition to formal thought disorder and discourse deficits, schizophrenic children underutilize self-initiated repair when presenting their thoughts to the listener, particularly if they are being treated with neuroleptics, a potential sign of increased clinical morbidity. Impoverished communication skills might reflect negative signs in childhood-onset schizophrenia.