Determination of effective pair interactions from the structure factor

In this work we present an efficient procedure to evaluate effective pair potentials, compatible with "experimental" structure factors, using a Monte Carlo simulation scheme. The procedure does not require the use of inverse Fourier transforms and is robust and rapidly convergent. As a test case the structure factor of liquid Selenium obtained from a Tight-Binding Molecular Dynamics simulation is inverted to obtain an effective pair potential and, as a by-product, the pair distribution function. The inversion procedure yields a pair structure in perfect agreement with the original molecular dynamics calculations and the analysis of the triplet structure and the dynamics also illustrates the limitations of the use of pair potentials in the description of liquids with strongly directional bonding, such as the covalent liquid Selenium.

Sister chromatid exchanges produced by imipramine and desipramine in mouse bone marrow cells treated in vivo

Imipramine and desipramine are two widely used tricyclic antidepressants which have shown conflicting results in regard to their in vitro genotoxic evaluation. The aim of this investigation was to determine the capacity of these compounds to induce in vivo sister-chromatid exchanges (SCEs) in mouse bone marrow cells. For each compound, the animals were organized in five groups constituted by five individuals. They were intraperitoneally (ip) administered with the test substances as follows: a negative control group treated with 0.4 ml of distilled water, a positive control group administered with cyclophosphamide (70 mg/kg), three groups treated with imipramine (7, 20 and 60 mg/kg), and three other groups treated with desipramine (2, 20 and 60 mg/kg). The general procedure included the subcutaneous implantation to each mouse of a 5-bromodesoxyuridine tablet (45 mg), and 1 h later, the administration of the chemicals involved. Twenty-one hours after the tablet implantation, the mice received colchicine, and 3 h later their femoral bone marrow was obtained in KCL, fixed, and stained with the Hoechst-Giemsa method. The results showed that both compounds were SCE inducers, starting from the second tested dose. The response of these compounds was dose-dependent, and showed that the highest tested dose increased about four times the SCE control level. The cellular proliferation kinetics was not affected by the chemicals, and the mitotic indexes were slightly diminished with the highest dose. These results indicate an in vivo genotoxic potential for both chemicals, and suggest that it is pertinent to follow their evaluation in other models.

[Adaptation of microtitration plate methods for quantification of the activity of esterases and glutathione-s-transferase in Aedes aegypti]

The detection techniques for the activity of non-specific esterases and glutathione-s-transferase in Culex quinquefasciatus were modified to detect such enzymes in Aedes aegypti(L). The optimal concentration values of substrate (saturating concentration) and the optimum reading time for reaction were determined for each enzyme by using 4 Aedes aegypti strains: one from Cuba 2 from Venezuela and one susceptible reference strain. The frequency of non-specific esterases turned out to be 0.76 in MIRANDA 0.42 in ARAGUA and 1 in SANTIAGO DE CUBA in which the highest frequency value of this mechanisms was reached. The frequency of glutathione-s-transferase mechanism was 0.45 in ARAGUA 0.043 in MIRANDA and 1 in SANTIAGO DE CUBA. For the first time in Cuba a set of biochemical techniques was available for detecting the resistance mechanisms of Aedes aegypti which made it possible to create sound foundations for the easy rapid detection of the resistance of this species the main dengue vector in the Americas.

[High esterases as mechanism of resistance to organophosphate insecticides in Aedes aegypti strains]

Five strains of Aedes aegypti L. one from Cuba and 4 from Venezuela were evaluated to determine their resistance to organophosphate insecticides (temephos, chlorpiriphos and pirimiphos methyl). In the Venezuelan strains only APURE showed resistance to temephos. In TACHIRA and MIRANDA moderate resistance values were noted (FR50 5 to 10x) for chlorpiriphos and high levels of resistance (FR > 10x) to this insecticide were found in ARAGUA. All the Venezuelan strains showed high levels of resistance to pirimiphos methyl. The Cuban strain from Santiago de Cuba revealed moderate resistance to temephos and pirimiphos methyl, but high resistance to chlorpiriphos. The results of the biochemical tests proved the presence of esterase and glutathione-s-transferase at high frequency in almost every strain. By the polyacrilamide gel electrophoresis, a strongly stained band was observed in all the strains with a Rf value of 0.779; it was named esterase A4 and was not seen in the susceptible reference strain. The meaning of this esterase in the resistance to organophosphate insecticides is yet to be determined. Resistance to these insecticides in Aedes aegypti is a serious problem for the control of this species therefore integrated management strategies were proposed to prevent or delay the appearance of this species in Cuba and Venezuela.

In vivo and in vitro induction of sister-chromatid exchanges by nordihydroguaiaretic acid

Nordihydroguaiaretic acid (NDGA) is a phenolic lignan previously used as an antioxidant in commercial products, and with a number of properties potentially useful to man. As its genotoxic capacity has been poorly evaluated, in this investigation we determined its effect on the production of sister-chromatid exchanges (SCEs), and on the level of mitotic index (MI) in cultured human lymphocytes and in mouse bone marrow cells in vivo. The proliferative index (PI), and the average generation time (AGT) were also determined for human lymphocytes and in mouse bone marrow cells respectively. The in vitro study was made in two donors using NDGA doses of 1.1, 3.6, 6.7, 13.5, and 27.0 microM; and for the in vivo study the tested doses were 8.8, 17.6, 35.3, and 70.7 mg/kg of body weight. The results concerning SCE induction in human lymphocytes showed a dose-dependent response with a maximum mean increase of 5.52 SCE in relation to the control level, and with respect to MI and PI a decrement of more than 50% and a cell cycle delay was detected only with the high dose. In the study with bone marrow cells, a statistically significant difference was determined with the high two doses (an increase of 1.06 SCEs with 70.7 mg/kg in relation to the control level). The MI decreased only with the high dose and no modification was observed with respect to AGT. In conclusion, in both used models the study demonstrated that NDGA produced genotoxic and cytotoxic effects.

DNA interaction and electrochemical properties of bis-1-aminomethylnaphthalenes and related compounds. A correlation with their antineoplastic activity

Bis-1-aminomethylnaphthalenes constitute a new type of molecule with antineoplastic activity. As a first approach to determine the action mechanism, the interaction degree of these compounds and some less active analogous, with calf thymus DNA, by UV spectrophotometry, and the redox performance by cyclic voltammetry was correlated with their activity on neoplastic cell lines. It suggests that the most active members interact closely with DNA but do not show any redox process at biological potentials.

Pigmented longitudinal bands of the nail. A clinicopathologic study

Eighteen patients with pigmented longitudinal bands of the nail were evaluated. The following clinical data were obtained: age, gender, and race, duration of the pigmented bands, description and location of the lesion, history of any clinical changes; other nail changes; and family and past history. Nail matrix and/or nail bed biopsy were performed in all cases. The histopathologic findings of 18 patients with longitudinal melanonychia showed hyperpigmentation of the epidermis with no apparent increase in the number of melanocytes in 10 cases. One case showed melanoma in situ; another showed keratinocytic proliferation with focal atypia. Three cases showed subungual hemorrhage. The cause of solitary pigmented bands is often not readily apparent, making the clinical diagnosis challenging. Melanotic macule of the nail matrix, consisting of increased pigmentation of the epidermis with no apparent increased in the number of melanocytes, seems to be the most common cause. When the cause of longitudinal melanonychia is not clinically apparent, biopsy of the nail matrix and the nail bed should help to establish it.

Morphological modifications of the choroid plexus in a rodent model of acute ventriculitis induced by gram-negative liquoral sepsis. Possible implications in the pathophysiology of hypersecretory hydrocephalus

Gram-negative bacterial infections of the central nervous system are generally associated with high morbidity and mortality rates. In patients with ventriculitis induced by gram-negative liquoral sepsis, a reduction in cerebrospinal fluid formation has been reported, suggesting that gram-negative ventriculitis is able per se to alter the normal functioning of the choroid plexus. The aim of the present study was to analyse, for the first time in the rat, the effects of acute ventriculitis on the ultrastructure of the choroid plexus. A simple and inexpensive experimental model of acute ventriculitis was developed: we injected into the cisterna magna of rats 10(3) CFU of live Escherichia coli, inducing septic ventriculitis without major neurological deficits. Histological examinations of rodent choroid plexus 24 h after the injection revealed patches of altered epithelium, with swollen and vacuolated ependymal cells associated with leukocyte infiltration. Electron microscopy demonstrated a reduced number of microvilli and flattening of the epithelial surface. These results (a) indicate that gram-negative septic ventriculitis is able to induce visible ultrastructural alterations of the choroid plexus which (b) are consistent with a picture of marked reduction of the functioning epithelial choroid plexus surface, and (c) highlight the potential usefulness of our rodent acute ventriculitis model for developing treatment modalities.

Intraoperative monitoring of cerebral blood flow during ventricular shunting in hydrocephalic pediatric patients

Several studies have demonstrated lowered cerebral blood flow (CBF) in patients with hydrocephalus and symptoms of raised intracranial pressure. Ventricular shunting in such cases permits a sudden increase in CBF. The pathophysiology of functional brain deficit secondary to hydrocephalus is little understood. Improvement of the patient's clinical status after drainage of CSF suggests that cerebral dysfunction is not necessarily due to permanent brain damage. In fact, it improves rapidly after ventricular taps. In view of this it would be helpful to monitor cerebral perfusion. The transcranial Doppler (TCD) ultrasonography technique allows real-time monitoring of the intracranial circulation and makes it possible to evaluate the physiopathological correlation between ventricular dilatation and CBF. Continuous monitoring of the middle cerebral artery (MCA) by TCD was performed in three hydrocephalic children (2 months, 14 months, and 8 years old) during a ventricular-peritoneal shunt operative procedure. A TC-2000S device provided by an IMP-F fixed probe was utilized. In all patients, when the lateral ventricle was shunted and the CSF could flow away, a clear and sudden increase of flow velocity above 30% was detected. The pulsatility index (PI) was also pathologically increased in all patients. A gradual normalization of this index was revealed after the shunting procedure. Our experience has to be considered preliminary, but nonetheless, it suggests a clear correlation between hydrocephalic disease and concomitant CBF alterations.(ABSTRACT TRUNCATED AT 250 WORDS)

Turcot's syndrome: a new case in the first decade of life

A case of Turcot's syndrome is described in an 8-year-old girl. Turcot's syndrome is a rare hereditary disease in which malignant glioma of the central nervous system is associated with colonic polyposis. The patient initially presented with a left parietal glioblastoma diagnosed by computed tomography (CT), and was subsequently found to have nonfamilial colonic polyposis.

Intracranial solitary-type infantile myofibromatosis

An unusual case of infantile myofibromatosis of the solitary type occurring in an intracranial location in a 48-day-old female infant is presented. To our knowledge, there are no other descriptions in the literature of infantile myofibromatosis with exclusively intracranial involvement. The immunohistochemical and electron microscopic findings confirm the myofibroblastic origin of the proliferation.

[Histrionic personality disorder in a psychiatry department at a general hospital]

The personality disturbances imply problem within the psychiatric assistance, both for its difficult delimitation and classification and for the limited results and bad use obtained from therapeutic resources. We studied 402 patients psychiatric service of a general hospital over a period approximately 2 years, 70 (17.5%) were diagnosed DSM-III with Personality disturbances: 44 females (62.9%) and 26 males (37.1%), of an age group between 18 and 67 years old. The most frequent diagnosis was of histrionic of the personality followed by unspecific and border-line. Within the histrionic disturbance of the personality there was a clear predominance of women, whereas in the others types, no significant differences were observed.

Outcome of craniocerebral trauma in infants and children

The authors examined 927 patients affected by craniocerebral trauma and analyzed the neurological complications that occurred most frequently. The study confirmed that the percentage of craniocerebral trauma, gravity, and complications were different in relation to the sex and age of the patients. Based on this analysis, a correlation was made between the traumatic pathologies and socioeconomic-environmental conditions.

Occupational vitiligo due to unsuspected presence of phenolic antioxidant byproducts in commercial bulk rubber

We investigated the occurrence of cutaneous depigmentation (vitiligo) among employees of a company that manufactured hydraulic pumps. The interiors of these pumps were injection-molded with rubber. We identified a small but significant cluster of vitiligo cases among a group of employees who frequently handled the rubber used in this injection molding process. Although none of the additives specified in the rubber formulations was a phenolic or catecholic derivative, known to be potential causes of chemically induced vitiligo, gas chromatographic analysis identified a para-substituted phenol (2,4-di-tert-butylphenol, DTBP) in solid samples of the most frequently used rubber. Surface wipe analysis confirmed that workers could be exposed to DTBP from simple handling of the rubber. We subsequently established that the solid bulk rubber used as the base in these stock rubber formulations contained both DTBP and smaller quantities of p-tert-butylphenol. Both had formed as unsuspected byproducts during chemical synthesis of two antioxidants added to the solid bulk rubber by a major rubber supplier. We conclude that the unsuspected presence of potential chemical depigmenting agents in solid bulk rubber, from which industrial rubber products are formulated, may contribute to the occurrence of occupational vitiligo, and that a simple review of ingredients in rubber formulations is inadequate to detect their presence.

An ion chromatographic method for insoluble chromates in paint aerosol

Potential exposure to Cr(VI) extends to over a million U.S. workers in the plating, paint, steel, tanning and chrome ore processing industries. Historically, Cr(VI) exposure has been monitored using a colorimetric method. This colorimetric method requires acidification of the sample for color development, a step that could cause reduction of Cr(VI) to Cr(III), thus underestimating the Cr(VI) content of the sample. A new method of analysis has been developed that uses ion chromatography (IC) for the measurement and which does not require acidification of the sample. In this method, the same extraction solution of hot 2% NaOH and 3% Na2CO3 as used in the earlier methods is used to dissolve both soluble and insoluble chromates (e.g., PbCrO4, ZnCrO4 and BaCrO4), but it can be carried through the method with only a dilution step before sample injection. Therefore, this method has the advantage of minimizing the potential for Cr(VI) loss by reduction. Another advantage is provided by the IC measurement step, which is not interfered with by colored samples that may affect the colorimetric method. The new method was tested with filter samples of paint aerosol containing PbCrO4 and ZnCrO4. Complete extraction of Cr(VI) from the filter samples was verified by comparison to an independent method in which the filter was completely ashed and analyzed by inductively coupled plasma-atomic emission spectroscopy method. Nothing in the paint samples interfered with the Cr(VI) measurement, nor did five common anions used in a separate test. The method had the sensitivity needed for monitoring at the ACGIH TLV of 0.05 mg Cr(VI)/m3.

Gas-liquid chromatography in routine processing of blood cultures for detecting anaerobic bacteraemia

Gas-liquid chromatography was performed on 233 positive blood cultures and findings were compared with culture results. Obligate anaerobic bacteria were recovered from 78 out of 79 blood cultures containing butyric or iso-valeric acids, or both; from 28 out of 69 blood cultures containing succinic acid; and from only one out of 41 blood cultures containing succinic but not butyric or iso-valeric acid. Good correlations (88%) were found for the recovery of anaerobic bacteria and the detection of butyric and/or iso-valeric acids. Detecting volatile fatty acids by gas-liquid chromatography performed on blood cultures at the first signs of growth can therefore provide an early and reliable indication of the presence of anaerobic bacteria.