The alternative H-ras protein p19 displays properties of a negative regulator of p21Ras

In previous work, we demonstrated that expression of mammalian H-ras genes is controlled by alternative splicing. Mutational analyses indicated that most H-ras premessenger RNA (pre-mRNA) is not processed into mRNA for the usual p21Ras protein, but is recognized instead for processing through an alternative pathway that would produce mRNA for a hypothetical p19Ras protein, which would be a truncated form of p21 with a different carboxyl-terminus. We have raised the possibility that p19 could be a negative regulator of p21, but only small amounts of mature p19 mRNA could be detected and we had no evidence that the protein could be made. We now show by transient and stable transfection experiments that p19 can be produced from complementary DNA (cDNA) expression vectors in human 293 cells, which express early adenoviral genes. However, p19 cDNA inhibited the formation of drug-selected colonies of Rat-1 cells and surviving colonies produced little p19. Colony formation and p19 expression were increased when the cDNA had mutations in the putative effector domain of p19 or when oncogenes believed to act downstream of p21Ras, such as adenoviral E1A, were included in the transfections. These results indicate that p19 can act as an inhibitor of p21. We also show that authentic p19 can be abundantly expressed in 293 cells from H-ras gene constructs with mutations favoring the alternative splicing pathway, which suggests that regulated splicing could support overproduction of p19 under natural conditions. Our work indicates that mutations abolishing alternative H-ras splicing may not only contribute to oncogenesis by increasing the production of p21, but also by interfering with the production of an antiproliferative H-ras activity.

A new anthracycline antibiotic, IT-62-B, converts the morphology of ras-transformed cells back to normal: taxonomy, fermentation, isolation, structure elucidation and biological characterization

A new antibiotic, IT-62-B was isolated from the culture broth of Streptomyces sp. IT-62 by extraction with acetone and then with ethyl acetate, followed by conventional column chromatography using silica gel, Sephadex LH-20 and silica ODS. Its structure (C39H47NO15, MW 769) was determined by 1H, 13C NMR, MS, IR and UV spectrometric techniques to be a new member of the baumycin-group anthracyclines. It showed moderate activity against Gram-positive bacteria and had antitumor activity against various tumor cell lines. Further, antibiotic IT-62-B converted the morphology of ras-transformed NIH3T3 cells and T-cells back to normal at concentrations inhibiting cell growth by 30% or more.

Molecular cloning and functional expression of cDNAs encoding a human Na+-nucleoside cotransporter (hCNT1)

We report identification of a new human nucleoside transporter protein by molecular cloning and functional expression of its cDNA. Previously, we used expression selection in Xenopus oocytes to isolate a cDNA from rat jejunal epithelium encoding the pyrimidine-selective Na+-dependent nucleoside transporter rCNT1 (Q.-Q. Huang, S. Y. M. Yao, M. W. L. Ritzel, A. R. P. Paterson, C. E. Cass, and J. D. Young. J. Biol. Chem. 269: 17757-17760, 1994). cDNAs for a human homologue of rCNT1, designated hCNT1, have been isolated from human kidney by hybridization cloning and reverse transcriptase polymerase chain reaction amplification strategies. hCNT1 was 83% identical to rCNT1 in amino acid sequence and exhibited the transport characteristics of an Na+-dependent nucleoside transporter with selectivity for pyrimidine nucleosides and adenosine when expressed in Xenopus oocytes. Deoxyadenosine, which undergoes net renal secretion, and guanosine were poor permeants. hCNT1 did, however, transport 3'-azido-3'-deoxythymidine. This is the first demonstration that members of the CNT family exist in human cells and provides evidence of their involvement in the renal transport of physiological nucleosides and nucleoside drugs. The hCNT1 gene was mapped to chromosome 15q25-26.

The effect of food on the bioavailability of ebastine

Two studies were performed to characterize the influence of food on the bioavailability of the current formulation of ebastine tablets. Study 1 was an open label, randomized, three-period, crossover food effect study where 18 healthy male volunteers received 10 mg ebastine after an overnight fast, a low-fat breakfast, and a high-fat breakfast. Study 2 was an open label, randomized, two period crossover food effect study where 12 healthy male volunteers received 20 mg ebastine after both an overnight fast and a high-fat breakfast. Plasma samples were obtained at selected times and analyzed for ebastine and carebastine, the active metabolite of ebastine, using a validated high-performance liquid chromatography assay. Biopharmaceutic parameters for carebastine, area under the plasma concentration-time curves (AUC (0-infinity)), and maximum plasma concentrations (C ( max ) ), were estimated using noncompartmental techniques and analyzed for statistical differences. AUC (0-infinity) and C(max estimates were 40%-50% and 30%-40% higher under fed conditions as compared with fasting conditions. The time to reach maximum concentrations (T(max)), the terminal elimination rate (K(e) ), and the half-life (t(1/2) ) were not significantly altered by the ingestion of a low-fat or high-fat meal. Statistical analyses of the natural logarithmic transformed data for AUC ((0-infinity) and C(max) also demonstrated significant differences between fasted and fed (low-fat and high-fat) conditions. This indicates that food had a statistically significant effect on the rate and extent of carebastine formation. Therefore, it may be concluded that administration with food maximizes the bioavailability of carebastine.

[The effects of gastrin-releasing peptide (GRP) and vasoactive intestinal polypeptide (VIP) on the prolactin (PRL) gene transcription of pitutitary PRL releasing tumor of rat]

The effects of gastrin-releasing peptide (GRP) and vasoactive intestinal polypeptide (VIP) on the prolactin gene transcription of cultured pituitary of male Sprague-Dawley (SD) rats PRL releasing tumor (PPRT) (induced by estradiol) cells were studied. The PRL mRNA levels were determined by in situ hybridization of cytoplasmic RNA with a DIG-labeled PRL cDNA probe. PRL mRNA levels didn't change when the PPRT cells were incubated with 10(-8) mol/L or 10(-7) mol/L GRP for 24 h, but decreased by 20% when GRP was increased to 10(-6) mol/L (P < 0.05). The PRL mRNA level increased to 1.60, 2.10, 2.21 times of the control group when the PPRT cells were respectively incubated with 10(-8), 10(-7), 10(-6) mol/L VIP for 24 h (P < 0.05). The PRL mRNA level didn't change when the PPRT tumor cells were incubated with 10(-8) mol/L E2 for 48 h, but did increase to 2.80 and 2.92 times of the control group respectively when 10(-7) mol/L and 10(-6) mol/L E2 were used. The results above indicated that GRP and VIP exert an inhibitory and a stimulatory effect on RPL gene transcription respectively, while the stimulatory action of E2 on PRL secretion is a direct one.

Mitochondrial NADH-coenzyme Q reductase deficiency in Leigh's disease

A 4 1/2-month-old girl suffered from psychomotor retardation, generalized hypotonia, poor feeding, hyperreflexia, nystagmus, optical atrophy and choreoathetosis from the age of 3 months. Her blood lactate level was elevated to 40 mg/dL. Magnetic resonance imaging of her brain showed low T1 and high T2 signal intensities in the bilateral putamen, thalamus, red nuclei, substantia nigra, superior and inferior colliculi, cerebral peduncles and periaqueductal lesions. Muscle histochemistry and electron microscopic examinations were all normal except for variation in fiber size showing a myopathic change. An assay of muscle mitochondrial respiratory enzyme activities revealed a deficiency of NADH-coenzyme Q reductase. Molecular analysis did not reveal the putative T to G transversion at the nucleotide 8,993 of mitochondrial DNA in muscle biopsies. Leigh's disease was indicated by the clinical and radiologic manifestations. The patient died at 10 months of age from pneumonia and respiratory failure. There have been only sporadic reports of patients with Leigh's disease in Taiwan, and, to our knowledge, this is the first documented case of a Taiwanese patient with mitochondrial NADH-coenzyme Q reductase deficiency.

Electrocardiographic findings in children with spinal muscular atrophy

Most of the patients in this study with spinal muscular atrophy were found to have tremors of the isoelectric line in the electrocardiogram (ECG) tracings. There were a total of 47 cases of SMA (mean age 40.8 months). All three types of SMA had a similar incidence (about 80%) of tremors in the tracings (p = 0.885). In 7 cases the ECG tremors had an intermittent pattern. ECG tremors were commonly found in the majority of SMA patients and this finding, though non-specific, may suggest a possible SMA diagnosis.

Interleukin-1 alpha stimulates osteoclast formation from peripheral blood monocytes and increases osteoclastic activity

BACKGROUND

Interleukin-1 (IL-1) is produced by monocytes and marrow stromal cells and can stimulate bone resorption in tissue culture. In addition, IL-1 can induce osteoclast-like cell formation in long-term bone marrow culture. However, whether IL-1 can increase osteoclast formation by stimulating fusion of peripheral blood monocytes is not clear. In addition, the precise effect of IL-1 on osteoclastic activity is still not well known.

METHODS

Using the bioassay of osteoclast formation, osteoclast-free fetal calvariae were harvested from 14-day timed-pregnant Sprague-Dawley rats and cultured in BGJb medium for 10 days. On the 10th day, mononuclear cells were obtained from peripheral blood of 8-week-old female Sprague-Dawley rats through cardiac puncture and Ficoll-Paque density gradient separation method and co-cultured with osteoclast-free developing bone explant. On the same day, various concentrations of IL-1 alpha (1,10 or 100 U/ml) were added daily in the experimental dishes while only BGJb medium was added in the controls. In addition, 45Ca release assay and quantitation of nuclei per osteoclast were performed to evaluate the effect of IL-1 alpha on osteoclastic activity.

RESULTS

Ten days after adding monocytes, there were 14.25 osteoclasts in the control, without IL-1 alpha; with 1 U of IL-1 alpha, there were 14.75 osteoclasts; with 10 U of IL-1 alpha, there were 18.00 osteoclasts; with 100 U of IL-1 alpha, there were 20.75 osteoclasts. In addition, IL-1 alpha stimulated the release of 45Ca and increased the number of average nuclei per osteoclast dose-dependently, indicating a significant increase in bone resorption.

CONCLUSIONS

IL-1 alpha could increase osteoclast formation by stimulating the fusion of peripheral blood monocytes. In addition, IL-1 alpha is a potent stimulator of osteoclastic activity.

Development and in vitro-in vivo evaluation of a multiparticulate sustained release formulation of diltiazem

PURPOSE

To develop and evaluate the in vitro/in vivo performance of diltiazem sustained release pellets that were prepared by the Wurster column process.

METHODS

Pellets containing diltiazem were prepared by spraying a slurry of micronized diltiazem hydrochloride, pharmaceutical glaze and alcohol onto an appropriate mesh fraction of nonpareil seeds using the Wurster column. A two-step drug layering process was used to increase drug loading from 60% to 75%. The oven-dried diltiazem basic pellets were coated with ethylcellulose/dibutyl sebacate coating solution to yield diltiazem sustained release pellets. An open, randomized Latin square, three-way crossover clinical study was used to evaluate the in vivo performance of the coated product.

RESULTS

Altering the mesh fraction of the starting nonpareil seeds for this layering process was found to affect the release characteristics of drug from the pellets. An oven-drying step was required to stabilize the diltiazem basic pellets. The thicker the drug loading layer the longer the oven drying is needed to stabilize the pellets. The diltiazem sustained release pellets produced by these methods displayed sustained release dissolution profiles both in vitro and in vivo. Diltiazem basic pellets coated with a 0.6% ethylcellulose/dibutyl sebacate coating showed a different rate of absorption (lower Cmax and higher Tmax) and the same extent of absorption as compared to Cardizem tablets.

CONCLUSIONS

Clinical data confirmed that this formulation approach is an effective means to produce a diltiazem sustained release product.

Relationship between left atrial pressure and atrial natriuretic peptide in children with cardiac disease

To evaluate the relationship between atrial pressure and the concentrations of atrial natriuretic peptide (ANP) in plasma of children with cardiac disease combined with increased left atrial loading. We extracted plasma ANP through a Sep-Pak C18 cartridge and proceeded to radioimmunoassay. Of the nine children, aged from 20 days to 10 years, cardiac diseases included transposition of the great arteries (four cases), ventricular septal defect (three cases), patent ductus arteriosus (one case) and mitral regurgitation (one case). The concentrations of ANP in plasma in the left atrium were greater than in the inferior vena cava, and the concentrations of ANP in plasma in the inferior vena cava correlated significantly with the mean left atrial pressure (r = 0.89, p < 0.01), and the concentrations of ANP in plasma in the left atrium correlated significantly with the mean left atrial pressure (r = 0.85, p < 0.01). This study indicated that left atrial pressure may have an important influence on secretion of ANP in various cardiac conditions.

Relationship between hemodynamics and plasma atrial natriuretic peptide in children with ventricular septal defect or patent ductus arteriosus

To evaluate the relationship between concentrations of ANP in plasma of the right-sided central circulation and hemodynamic parameters in congenital heart disease with left-to-right shunt. We enrolled 20 children aged from 1 month to 4.8 years with ventricular septal defect (VSD) or patent ductus arteriosus (PDA). The concentrations of ANP in plasma were extracted through a cartridge (Sep-Pak C18) before being measured by radioimmunoassay. Significant increased concentrations of ANP in plasma from inferior vena cava (117.6 +/- 18.1 pg/mL), right atrium (160.6 +/- 21.6 pg/mL) to pulmonary artery (PA) (253.4 +/- 38.8 pg/mL) were recognized. In VSD (n = 10) and PDA (n = 10), the concentrations of ANP in plasma from the inferior vena cava correlated significantly with the ratio of pulmonary to systemic blood flow (Qp/Qs) (r = 0.69, p < 0.05; r = 0.94, p < 0.01 respectively), the systolic pulmonary artery pressure (r = 0.90, p < 0.01; r = 0.93, p < 0.01 respectively), the diastolic pulmonary artery pressure (r = 0.76, p < 0.02; r = 0.68, p < 0.05 respectively), and the mean pulmonary artery pressure (r = 0.88, p < 0.01; r = 0.87, p < 0.01 respectively). The concentrations of ANP in plasma from the pulmonary artery also correlated significantly with the Qp/Qs (r = 0.81, p < 0.01; r = 0.87, p < 0.01 respectively). The results indicated that left atrial volume loading may have an important influence on secretion of ANP in some congenital heart disease with left to right shunt.

[Regulatory role of galanin on prolactin and beta-endorphin release from anterior pituitary lobe of rat]

The role of brain-gut peptide galanin in the regulation of prolactin (PRL) and beta-endorphin (beta-EP) release from anterior pituitary lobe was studied in vivo in conscious male rats and in vitro with cultured anterior pituitary cells of the rat. Galanin (1 microgram or 3 micrograms/rat) injected into the third cerebral ventricle of rats produced highly significant, dose-related increases of PRL resting secretion, but did not alter resting secretion of beta-EP and restraint stress-induced release of PRL and beta-EP. However, galanin (0.05, 0.5 and 1.0 micrograms/5 x 10(5) cells.ml-1) induced highly significant, dose-related increase of beta-EP secretion from dispersed anterior pituitary cells, but failed to alter significantly PRL secretion from the cultured cells. These results indicate that central galanin has a stimulatory role in pituitary PRL resting secretion via the hypothalamus, whereas peripheral galanin stimulates beta-EP secretion only via direct action of this peptide in anterior pituitary cells.

[Somatomedin-C in infantile nutritional assessment with comparison with prealbumin, insulin and growth hormone]

Somatomedin-C (Sm-C) is also called insulin like growth factor I (IGF-I). It has insulin-like biological effects and serves as an anabolism-related mediator of growth hormone. Most Sm-C is synthesized in liver cells. There are decreased blood levels of Sm-C, prealbumin and insulin, but increased blood levels of growth hormone in the adult with malnutrition. We simultaneously measured the blood levels of the above four peptides in infants aged one month to one year. They were divided into four groups: normal, first class malnutrition, second class malnutrition and third class malnutrition. They were classified according to the Value of Nutrition Index. The utility of Sm-C measurement was compared to that of the measurements of prealbumin, insulin and growth hormone in the nutritional assessment. The results revealed that the blood level of Sm-C decreased more in the cases of severe malnutrition (Normal group: male 361.2 +/- 158.9 mU/ml (n = 18), female 499.3 +/- 227.8 mU/ml; (n = 19); First class malnutrition group: 256.9 +/- 81.1 mUU/ml (n = 17); Second class malnutrition group: 169.5 +/- 43.5 mU/ml (n = 15); And third class malnutrition group: 76.2 +/- 26.5 mU/ml (n = 18)). The blood level of prealbumin decreased more in the cases of severe malnutrition (Normal group: 17.8 +/- 2.1 mg/dl (n = 37); First class malnutrition: 11.8 +/- 3.5 mg/dl (n = 17); Second class malnutrition: 11.8 +/- 3.5 mg/dl (n = 15); And third class malnutrition: 9.7 +/- 2.4 mg/dl (n = 18)).(ABSTRACT TRUNCATED AT 250 WORDS)

Modified filter synthetic discriminant functions for improved optical correlator performance

By the filter modulation operator N, the modified filter synthetic discriminant function permits advantageous preprocessing of individual training-set images that are used in a linear combination to construct the filter synthetic discriminant function, which applies a modulation operator M to the synthetic discriminant function. A relaxation algorithm is used to satisfy the equal correlation peaks rule in the correlator output plane. As the filter modulation operators M and N can be given any functional form, the modified filter synthetic discriminant function design proposed is sufficiently general to be described as a unified filter modulation synthetic discriminant function design.

Study on the children of Kaohsiung with acute viral infection of lower respiratory tract by direct immunofluorescence assay

This study retrospectively reviewed those pediatric patients of acute lower respiratory tract infection with positive virus identification by direct immunofluorescence assay (Direct IF) from Jan, 1992 to Dec, 1993. One hundred and eighteen patients with 133 positive Direct IF results (107 cases with single virus identified, and 11 cases with more than one) were included. The sex ratio was 1.6:1 with males predominant; age, 22.1 (1 approximately 154.8) (months); duration of admission, 5.7 (1 approximately 69) (days); peripheral white blood cell count, 10,600 +/- 3,800/mm3; C-reactive protein, 17.0 (0 approximately 163.3) mu/ml; body temperature, 37.1 +/- 1.1 degrees C in those cases with single virus. The symptoms were cough 105 cases (98.1%), rhinorrhea 46 cases (43.0%), dyspnea and/or tachypnea 43 cases (40.2%) and diarrhea 15 cases (14.0%). The viruses identified were: Adenovirus (52 cases, 39.1%). Influenza B (45 cases, 33.8%), Parainfluenza 1 (28 cases, 20.1%), Parainfluenza 3 (19 cases 14.3%), Respiratory Syncytial virus (17 cases, 12.8%), and Influenza A (9 cases, 6.8%). The seasonal incidence rates were spring (49 cases, 36.8%), summer (46 cases, 34.6%), autumn (23 cases, 17.3%), and winter (15 cases, 11.3%). The results showed much similarity with others, except the commonest viral type (Adenovirus in this study; Respiratory Syncytial virus in others) and the seasonal incidence rate (higher in spring and summer in this study but not in others). In conclusion, most children with acute viral lower respiratory tract infection had an uneventful course and Direct IF is a reliable method for viral detection in that disease.

Effects of smoking and drinking habits on urinary o-cresol excretion after occupational exposure to toluene vapor among Chinese workers

The relationship between the time-weighted average intensity of exposure to toluene and o-cresol concentration in shift-end urine was investigated in nearly 500 factory workers of both sexes in China, together with a similar number of nonexposed control subjects. Toluene concentration (25 ppm as geometric mean and 550 ppm as the maximum) was monitored by diffusive sampling using carbon cloth as adsorbent followed by gas chromatographic (GC) analysis. o-Cresol (up to 7 mg/l) was measured by GC after acid hydrolysis of samples. Urinary o-cresol levels correlated significantly (r = 0.69-0.77; p < 0.01) with toluene exposure in men, women and the two sexes in combination, regardless of correction for urine density. When compared with hippuric acid, however, o-cresol was less sensitive as an indicator of exposure to toluene and is not a suitable biological marker for detecting low level toluene exposure. Since urinary o-cresol level was significantly reduced by smoking, drinking, and the two habits combined, it cannot be considered reliable as an indicator of exposure to toluene.

Q-switched ruby laser treatment of benign pigmented lesions in Chinese skin

The Q-switched ruby laser has been demonstrated as an effective choice of treatment for a range of benign pigmented lesions. Its wavelength of 694 nm enables deep penetration of the skin allowing the treatment of both epidermal and dermal lesions. However, this wavelength is selectively absorbed by melanin thereby enabling efficient targeting of the lesion's melanocytes. By utilising a Q-switched pulsewidth of 25 nanoseconds, thermal conduction into surrounding tissues is minimised. Lesions such as nevus of Ota, chloasma, lentigines and cafe au lait have been successfully treated with energy densities ranging from 6 to 12 J/cm2. Four case histories are described in this report. The clinical evidence indicates that pigmented lesions in Chinese skin must be treated with energy densities higher than those used in Caucasian skin to minimise the incidence of hyper-pigmentation. Typically, lesions require a small number of treatments, usually within the range one to six, to effect complete removal. The technique is easy to apply, with no need for anaesthesia, in many cases.

Exposure of workers to a mixture of toluene and xylenes. I. Metabolism

The urinary excretion of hippuric acid and methylhippuric acid was studied in workers (233 subjects; 122 men and 111 women) exposed to toluene and xylenes in combination and in non-exposed controls (281 subjects; 141 men and 140 women) recruited from the same factories or factories of the same regions. Smoking and drinking habits of the subjects were obtained by medical interviews. From each worker, one urine sample was collected at the end of a shift and analysed for hippuric and methylhippuric acids by high performance liquid chromatography. Air samples for the estimation of toluene and xylenes were collected with diffusive personal samplers. There was a linear correlation between the time weighted average exposure either to toluene or xylene isomers and the concentrations of hippuric acid or methylhippuric acid isomers in urine. Essentially no difference was found in the correlation between quantitative exposure and excretion in the three xylene isomers. Comparison of the slopes of regression lines indicated the absence of metabolic interaction between toluene and xylenes at the measured concentrations. The metabolism of toluene and xylenes was significantly reduced among smokers or drinkers compared with non-smokers and non-drinkers.

The uses and limitations of DNA flow cytometry in stage IB or II cervical carcinoma

BACKGROUND

The role of flow cytometry in predicting prognosis for cervical carcinoma remains unclear.

METHODS

Flow cytometric analysis was performed on tissues, fixed in formaldehyde solution and embedded in paraffin, from 411 patients with Stage IB or II cervical carcinoma who had been treated with radical abdominal hysterectomy and bilateral pelvic lymphadenectomy.

RESULTS

DNA aneuploid-multiploid tumors were found in 37.5%, tetraploid in 4.6%, and diploid-peridiploid in 57.9%. Five-year recurrence-free survival rates of the three groups were 74.3%, 77.8%, and 76.4%, respectively (P > 0.05). DNA aneuploidy and DNA index (DI) of greater than 1.3 were highly correlated to parametria extension. In univariate analysis, pelvic lymph node metastases, stage, parametrial extension, depth of cervical stromal invasion, tumor size, and DI (1.3, 1.4, 1.5 as breakpoint) were significant prognostic factors. DNA ploidy, S-phase fraction, and S-G2M fraction were not significant. In multivariate analysis, DI of greater than 1.3, pelvic node metastases, clinical Stage II, and depth of stromal invasion greater than two-thirds of full cervical thickness were independent and significant variables. The prognostic index (PI), defined by the model, was able to categorize the patients into three distinct risk groups. The 5-year recurrence free survival rates of the low-, intermediate-, and high-risk groups were 89.5%, 73.0%, and 58.9%, respectively (P < 0.0001).

CONCLUSIONS

The prognostic value of the DI as a single variable is promising and warrants additional investigation to establish its appropriate use.

[Pancreatic polypeptide in the control of beta-endorphin and prolactin release from rat anterior pituitary in vivo and in vitro]

This study was designed to examine the possible effects of pancreatic polypeptide (PP) on beta-endorphin (beta-EP) and prolactin (PRL) release from rat anterior pituitary in vivo and in vitro. Injection of 0.5 microgram or 2.0 micrograms PP into the third ventricle of the brain (3rd v.i.) produced a significant decrease of the beta-EP and PRL resting secretion. 0.5 microgram PP (3rd v.i.) did not affect restraint stress-induced release of beta-EP, but partially lowered stress induced release of PRL. 2.0 micrograms PP (3rd v.i.) partially reduced restraint stress-induced release of beta-EP and completely suppressed stress-induced release of PRL. In order to investigate a possible direct action of PP on beta-EP and PRL secretion from the anterior pituitary gland, we incubated dispersed anterior pituitary cells with synthetic PP (0.05, 0.625 and 1.00 micrograms) for 1 n, the secretion of beta-EP was not affected at any dosage tested, but 0.625 and 1.00 micrograms PP significantly decreased the PRL secretion. These data indicate that PP may have an inhibitory role in the control of beta-EP secretion at the level of the hypothalamus, and an inhibitory role in the control of PRL secretion at the level of either hypothalamus or anterior pituitary.

Symptoms and signs in workers exposed predominantly to xylenes

Surveys were conducted in factories in China where workers were engaged in the production of rubber boots or plastic-coated wire or in printing work, and were exposed to xylene vapors. Based on the data on exposure as monitored by personal diffusive sampling, 175 xylene-exposed workers (107 men and 68 women) were selected as those (1) who underwent all examinations and (2) for whom the sum of the three xylene isomers accounted for 70% or more of the total exposure (on a ppm basis). The intensity of exposure was such that the sum of the three isomer concentrations was 14 ppm as a geometric mean and 21 ppm as an arithmetic mean. As controls, 241 nonexposed workers (116 men and 125 women) were recruited either from the same factories or from factories in the same regions. There was an increased prevalence of subjective symptoms in the exposed workers which were apparently related to the effects on the central nervous system and to the local effects on the eyes, the nose, and the throat, although dose-dependency of the symptoms was evident in only a limited number of cases, possibly because the intensity of exposure was rather low. It was further observed that the findings of hematology and serum biochemistry in respect of liver and kidney functions were generally negative, showing that xylenes are not toxic to the hematopoietic organs, the liver, or the kidney.

Effect of hamster liver passage on the isoenzyme patterns of Entamoeba histolytica

The effect of hamster liver passage on the isoenzyme patterns of isolates of Entamoeba histolytica was investigated. Three isolates, F, G and T were originally obtained from patients with acute amebic dysentery and another strain, C, was obtained from an asymptomatic carrier. All these strains were maintained for over two years in axenic culture. The isoenzyme pattern (zymodeme) of hexokinase (HK), phosphoglucomutase (PGM) and glucose phosphoisomerase (GPI) of these strains was found to belong to non-pathogenic group X, but the isoenzyme pattern of GPI resembled less pathogenic zymodeme XX and might be an intermediate type. Following inoculation of trophozoites into hamster livers and recovery after abscess formation, their isoenzyme pattern changed and revealed that they belonged to pathogenic type XIV. Liver passage caused an enhancement in amebic virulence as evidenced by their increased ability to destroy leukocytes. The results indicate that isoenzyme pattern is not a stable property of E. histolytica.

Absence of blue-yellow color vision loss among workers exposed to toluene or tetrachloroethylene, mostly at levels below occupational exposure limits

Possible color vision loss was examined with Lanthony's new color test and Ishihara's color vision test in 261 solvent workers and 120 controls (48 men and 72 women). The solvent workers were exposed to either predominantly toluene [46 ppm as geometric mean (GM); 63 men and 111 women], tetrachloroethylene alone (13 ppm; 30 men and 34 women), or a mixture (14 men and 9 women) of tetrachloroethylene (12 ppm) and trichloroethylene (7 ppm). The only instances of color vision loss that were detected in either the exposed workers or the controls were six cases of red-green loss (all in men). These six cases of red-green loss showed an unbiased distribution between the exposed workers and the nonexposed controls.