Morphometric analysis of developing zebrafish embryos allows predicting teratogenicity modes of action in higher vertebrates

The early identification of teratogens in humans and animals is mandatory for drug discovery and development. Zebrafish has emerged as an alternative model to traditional preclinical models for predicting teratogenicity and other potential chemical-induced toxicity hazards. To prove its predictivity, we exposed zebrafish embryos from 0 to 96 h post fertilization to a battery of 31 compounds classified as teratogens or non-teratogens in mammals. The teratogenicity score was based on the measurement of 16 phenotypical parameters, namely heart edema, pigmentation, body length, eye size, yolk size, yolk sac edema, otic vesicle defects, otoliths defects, body axis defects, developmental delay, tail bending, scoliosis, lateral fins absence, hatching ratio, lower jaw malformations and tissue necrosis. Among the 31 compounds, 20 were detected as teratogens and 11 as non-teratogens, resulting in 94.44 % sensitivity, 90.91 % specificity and 87.10 % accuracy compared to rodents. These percentages decreased slightly when referred to humans, with 87.50 % sensitivity, 81.82 % specificity and 74.19 % accuracy, but allowed an increase in the prediction levels reported by rodents for the same compounds. Positive compounds showed a high correlation among teratogenic parameters, pointing out at general developmental delay as major cause to explain the physiological/morphological malformations. A more detailed analysis based on deviations from main trends revealed potential specific modes of action for some compounds such as retinoic acid, DEAB, ochratoxin A, haloperidol, warfarin, valproic acid, acetaminophen, dasatinib, imatinib, dexamethasone, 6-aminonicotinamide and bisphenol A. The high degree of predictivity and the possibility of applying mechanistic approaches makes zebrafish a powerful model for screening teratogenicity.

Threadworms: a starting point for family hygiene

Owing to the embarrassing anal itch caused by threadworm infection, some sufferers feel they cannot even mention the problem to their doctor. Community nurses, often regarded as a more approachable source of support, will also be able to prescribe medication if they have prescribing status. With an adequate understanding of the complaint, they can offer a choice of treatment options, mechanical removal or drugs, necessarily backed by the appropriate personal and environmental hygiene measures. The starting point for relevant hygiene is cheerful good practice in hand washing at home and school, which is also key to preventing the spread of many other more serious infections. Implementation is of basic importance and should form part of any of the current initiatives from Sure Start to Healthy Schools.

Head lice: changing the expensive chemotherapy culture

The revulsion prompted by the discovery of head lice on a child's head, and the money spent by the NHS each year on supplying licensed medicines for head lice, is disproportionate to the medical impact that lice have on their hosts. This article discusses the evidence available on the effectiveness of the commonest parasiticidal preparations, and argues the case for a more rational, simpler and cost-effective response to this common problem.

Absence seizures effects on reading revealed by video-electroencephalography

OBJECTIVE

The effects of absence seizures on reading have not been studied. The purpose of this paper is to show some alterations in reading during absence seizures in patients with video-electroencephalographic recordings.

METHODS

Patients were selected if absences seizures were the only type of seizures. They were studied at rest with eyes closed and while reading aloud a text by simultaneous bipolar electroencephalographic and video recordings.

RESULTS

Eight patients were studied with 34 events. Absences ranged from 1-12 events in twenty-five minutes recording, seizures duration ranged from 1.5-16 seconds. Brief seizures results on non-stop reading, but reading arrest with latency of 1-3 seconds after seizure onset were present in the longer events. Post-absence amnesia ranged from 1-4.5 seconds. Re-start reading occurs mainly in other reading place in the text, but two patients in one event re-started reading in the right place. Classic symptoms during absence were present and reading alterations found were: reading arrest, lost of reading point, bradylexia, dysprosodic reading, grapheme substitution, reading loudness reduction, repeating of phrases. Events occurred without patient seizure awareness, except in one patient by means of the time lost between onset to the end of the event.

CONCLUSIONS

This study showed that acute reading alterations during absence seizures are frequent in longer seizures, producing many neuropsychological symptoms that alter reading without seizure awareness.

Circulating monocytes in patients with diabetes mellitus, arterial disease, and increased CD14 expression

Low serum concentrations of high-density lipoprotein (HDL) cholesterol and elevated levels of acute-phase reactans are frequently found in patients with non-insulin-dependent diabetes mellitus (NIDDM) and cardiovascular disease. Changes in the phenotype of circulating monocytes have been reported with both of these circumstances in nondiabetic subjects. In the present study, we explored the possibility that similar changes may occur in circulating monocytes of patients with NIDDM and arterial disease. Two groups of subjects with NIDDM were studied: patients with cardiovascular disease (n = 25) were compared with a group without cardiovascular disease (n = 26); both groups were age- and sex-matched, had the same length of diabetes duration, and degree of glycemic control. Healthy nondiabetic volunteers of comparable age and sex (n = 35) formed the control group. There was no significant difference in the numbers of the CD14+/CD16+ monocyte subpopulations between the 3 groups. However, a significant graded increase of the mCD14 intensity expression values was observed among the groups, with the highest levels in patients with NIDDM patients and the lowest in nondiabetic subjects. The serum C-reactive protein concentrations were significantly higher in the group with arterial disease compared with those without arterial disease or healthy controls. In the group of patients as a whole, relative mCD14 intensity expression was significantly correlated with HDL cholesterol levels (inversely) and with serum concentrations of C-reactive protein. Serum HDL cholesterol levels and the C-reactive protein concentrations were also significantly correlated. We concluded that the increased mCD14 intensity expression on circulating monocytes may be an important contributor to the increased inflammatory response observed in patients with NIDDM and arterial disease, and eventually, to atherogenesis.

Electrophysiological and behavioral methods in early detection of hearing impairment

BACKGROUND

Recent advances in neonatal life-support systems have contributed to the survival of high-risk newborns. However, protection of the auditory system and the prevention of sequelae is still paramount in neonatal neurology. The aim of this study was to compare auditory-evoked responses with a toy test and acoustic reflex in the early detection of hearing loss in infants.

METHODS

Three groups were studied. The first was composed of infants showing less than a 30 dB biaural threshold in the neurophysiological test. The second group was made up of infants showing peripheral alterations on one side or both ears. The third group was comprised of infants who showed no responses at 95 dB HL in both ears after neurophysiological testing. The neurophysiological test, toy test, and acoustic reflex were performed on the same day, with masked results given to each investigator. Sensitivity and specificity for each toy test and acoustic reflex were calculated afterward.

RESULTS

Forty-five controls, 44 peripheral alterations, and 8 non-response infants were studied. Most patients studied were born prior to the 37(th) week of gestation with a birthweight of less than 2,250 g, received required administration of potential ototoxic drugs and mechanical ventilation, and showed hyperbilirubinemia and hypoxia. Sensitivity for each toy was as follows: drum 0.54; wooden rattle 1.0, and metallic ratle 0.88. Specificity was 0.95, 1.0, and 1.0, respectively. Acoustic reflex sensitivity was 0.38 and specificity was 0.97.

CONCLUSIONS

Results suggest that the wooden and the metallic rattles of the toy test can be useful tools in the study of hearing in the high-risk infant and deserve more attention in future studies.

Interference of antibody production to hepatitis B surface antigen in a combination hepatitis A/hepatitis B vaccine

A randomized trial comparing 3 manufacturing consistency lots of a combination hepatitis A/hepatitis B vaccine to each other and to hepatitis A vaccine and hepatitis B vaccine given separately and concurrently was done to evaluate safety, tolerability, and immunogenicity. Healthy volunteers >/=11 years of age were divided into 4 groups. Each of 3 groups received a separate consistency lot of the combination vaccine, and 1 group received separate but concurrent injections of hepatitis A and hepatitis B vaccines. Injections were given at weeks 0 and 24. The combination vaccine was generally well tolerated. The hepatitis A portion of the combination vaccine produced clinically acceptable high seropositivity rates 4 and 52 weeks after the first injection. The hepatitis B portion of the vaccine did not produce clinically acceptable seropositivity rates 4 weeks after the second injection. Lack of antibody production may be attributed, at least in part, to immunologic interference.

Toxicity of Bacillus thuringiensis beta-exotoxin to three species of fruit flies (Diptera: Tephritidae)

The current study describes toxic effects of the Bacillus thuringiensis beta-exotoxin toward 3rd instars of 3 fruit fly species: Anastrepha ludens (Loew), A. obliqua (Macquart), and A. serpentina (Wiedemann). The beta-exotoxin was highly toxic to all 3 species tested, with LC50 values calculated as 0.641, 0.512, and 0.408 microgram/cm2 of filter paper used to expose the larvae, for A. ludens, A. obliqua, and A. serpentina, respectively. Exposure to beta-exotoxin was associated with an increase in the incidence of deformed pupae. The adult survivors from beta-exotoxin treatments showed no negative effects in terms of their longevity, fecundity, or egg eclosion (fertility). We conclude that the beta-exotoxin may have potential as a control agent for fruit fly pests.

[Dry powdered formoterol, twice a day versus aerosolized salbutamol, four times a day, in patients with stable asthma]

MATERIAL AND METHODS

The objective of this multicenter, open randomized study was to compare the effect of inhaled formoterol (dry powder with ISF system) 12 mcg twice daily versus salbutamol (200 mg qid) in patients with bronchial asthma. A total of 160 patients were evaluated with such diagnosis in four specialized centers; the main variable was the maximal respiratory flow (MEF) assessed prior to drug administration (morning and afternoon). In addition to this, vital capacity (VC), forced respiratory volume over one second (FEV-1), and other safety variables were also determined.

RESULTS

With regard to MEF the administration of formoterol showed better results (P < 0.05) ever since the first month of treatment. The frequency of adverse events was similar between treatment groups; the formoterol group had fewer nightly wake up periods.

CONCLUSIONS

That formoterol is a safe, efficacious and long-acting Beta 2 agonist which can be administered twice daily.

A guide to common parasitic diseases

The Primary Health Care Guide to UK Parasitic Diseases is aimed at health professionals working in primary care and offers an easy reference and practical advice on prevention, recognition and management of parasitic disease. Here, some of the key points are summarised.

[Tuberculosis outbreak: significance of exposure time versus proximity to infection source]

BACKGROUND

The polymorphic length restriction fragment technique (PLRF) complements epidemiologic investigations. The aim of this study was to present an outbreak of tuberculosis in which the risk factors of infection and disease were studied.

PATIENTS AND METHODS

A descriptive study was carried out in cases of tuberculosis. The isolated strains of Mycobacterium tuberculosis were typed by the PLRF technique. A study of the prevalence of infection was carried out among the 61 classmates of two classrooms (A and B) which the index case attended. An historical cohort study was thereafter performed among the cases with infection. The association of the dependent variable (infection or tuberculosis disease) with the remaining variables was determined by the odds ratio (OR).

RESULTS

The incidence of disease was 9.8% (6/61). The strains isolated in 5 patients presented the same PLRF pattern. The prevalence study detected 28 infections (45.9%). Five cases (17.9%) were detected on the second tuberculin test. By multivariate analysis showed that the hours of exposure (1.8-3.2 hours, OR = 2.0; > 3.2 hours; OR = 10.2) were the risk factor for infection. The BCG vaccine, the intensity of the reaction to the tuberculin test and age could be associated with the risk of disease.

CONCLUSIONS

The focus of the outbreak was confirmed by the PLRF technique. The importance of repeating the tuberculin test in whom the test was negative on the first test is of note. To evaluate the risk of infection the time of exposure is more important than the proximity to the index case.

Simple coherence measurement with a modified Lau interferometer

We measure mutual intensity in quasi-monochromatic light. Our setup is simple, without a lens. A rotating grating and a one-dimensional receiver are the only pieces of hardware. The action of our system can be understood as that of a mock Lau interferometer.

Adenocarcinoma in a müllerian duct cyst

A case of adenocarcinoma involving a müllerian duct cyst is presented. The presentation, treatment, and pathological and radiological appearance are discussed. The embryology and history of this entity are reviewed.

Dynamics of the inward rectifier K+ current during the action potential of guinea pig ventricular myocytes

The potassium selective, inward rectifier current (IK1) is known to be responsible for maintaining the resting membrane potential of quiescent ventricular myocytes. However, the contribution of this current to the different phases of the cardiac action potential has not been adequately established. In the present study, we have used the action potential clamp (APC) technique to characterize the dynamic changes of a cesium-sensitive (i.e., Ik1) current which occur during the action potential. Our results show that (a) Ik1 is present during depolarization, as well as in the final phase of repolarization of the cardiac action potential. (b) The current reaches the zone of inward-going rectification before the regenerative action potential ensues. (c) The maximal outward current amplitude during repolarization is significantly lower than during depolarization, which supports the hypothesis that in adult guinea pig ventricular myocytes, Ik1 rectification is accentuated during the action potential plateau. Our results stress the importance of Ik1 in the modulation of cell excitability in the ventricular myocyte.

Dynamics of the background outward current of single guinea pig ventricular myocytes. Ionic mechanisms of hysteresis in cardiac cells

Subthreshold potentials are thought to be mediated by time-independent, "passive" background currents. In this study, we show that the background current-voltage (I-V) relation of guinea pig ventricular myocytes is changed significantly by repetitive stimulation, in such a way that cell excitability becomes enhanced. Myocytes were used for whole-cell voltage-clamp experiments. A voltage-clamp ramp (100 mV/sec) to -50 mV was applied from a holding potential of -100 mV. Subsequently, a train of square voltage-clamp pulses to +10 mV (duration, 300 msec; interpulse interval, 300 msec) was delivered from a holding potential of -85 mV. A new ramp was applied again immediately after the train, and the resulting I-V curve was compared with that obtained before the train. Pulsing displaced the I-V relation to the right, the zero-current point becoming 1-2 mV less negative, and increased the degree of inward-going rectification. These changes were insensitive to tetrodotoxin (30 microM); disappeared during superfusion with cobalt (2 mM), verapamil (22 microM), or ryanodine (5 microM); and could not be mimicked by agonists of the protein kinase C system. In the presence of cesium (8 mM), pulsing still displaced the I-V curve to the right. However, the linear portion of the curve became steeper after the train. Subtraction of the cesium-sensitive current from control revealed that, although the zero-current point remained constant, the I-V relation showed a stronger inward-going rectification after pulsing. In accordance with these results, we have demonstrated hysteresis of excitability in ventricular myocytes. We conclude that the observed changes are mediated by an increase in intracellular calcium, which leads to an increase in rectification of IK1, as well as to activation of another membrane-conductance system, perhaps the Na-Ca exchange or the Ca(2+)-activated, nonselective current.

[Postneonatal mortality caused by diarrhea: a case-control study]

A matched case-control study was undertaken in Naucalpan de Juárez, Estado de México. The goal of this study was to identify the risk factors for diarrheal disease in children between seven days and one year of age. We identified 63 case and 188 controls. The most important risk factors were: mother's age greater than 36 years with an odds ratis (OR) 3.7, lack of breastfeeding (OR 11.3), breast and bottle feeding (OR 5.4), lack of intradomiciliary sewage (OR 8.3), repeated episoded of disease (OR 8.6) and father's consumption alcoholic beverages (OR 3.6). The main possible paths by which these factors influence mortality are discussed. Specific interventions for some of the factors are proposed.

Holographic interferometer with tunable radial and lateral displacement

The hologram of a point source, together with the real point source, is used to implement a simple holographic interferometer that can be tuned in its radial and/or lateral displacements. We show that our device is easy to use for creating cosinusoidal gratings and zone plates and for optical testing.

[Effects of caffeine on post-extrasystolic potentiation and mechanical restitution in mammalian papillary muscle]

The excitation-contraction coupling theory postulates that the main source of activator calcium is the sarcoplasmic reticulum that releases calcium in response to an electrical stimulus. This happens to be true in skeletal muscle, but recently several discrepancies have been raised about the validity of this hypothesis in cardiac muscle. These discrepancies are related to morphological as well as physiological data. The new information postulates that sarcoplasmic reticulum in cardiac muscle does not supply calcium as a main source in physiological conditions. The aim of the present paper was to evaluate the sarcoplasmic reticulum role in the supply of activator calcium in excitation-contraction coupling. A series of experiments were performed using the mechanical restitution and the post-extrasystolic potentiation models in the presence of caffeine, which is known to provoke functional elimination of the sarcoplasmic reticulum. It was observed that caffeine diminished the post-extrasystolic potentiation when 1 mM was used. At higher dose (4mM) the post-extrasystolic potentiation was completely abolished. On the other hand the late part of mechanical restitution is also abolished by caffeine. The amount of calcium that recirculates seems to increase in the presence of caffeine. The results obtained seem to support the idea that the sarcoplasmic reticulum has only a minor role in the supply of activator calcium, when physiological stimulation rates are used.

Reflex regional vascular responses during passive gastric distension in cats

The increase in systemic vascular resistance during gastric distension in cats may result from variable vasomotor responses in several parallel regional vascular beds. Accordingly, in 23 anesthetized cats the stomach was passively distended with a balloon while systemic hemo-dynamics were monitored. Regional vascular responses were determined during control periods and during gastric distension either by injection of radioactive microspheres (15 cats) or by constant perfusion of vascularly isolated organs (8 cats). During distension, mean arterial pressure and systemic vascular resistance increased by 32 and 28%, respectively. Regional flow measurements indicated no significant alterations in any of the organs examined. Calculated regional vascular resistances indicated vasoconstriction in the kidneys (53%), small intestine (31%), and large intestine (37%) that was reversed by alpha-adrenergic blockade with phentolamine. Constant-flow perfusion studies confirmed the regional vasoconstriction in the renal, superior mesenteric, and hindlimb circulations. These studies suggest a regional heterogeneity of vasomotor response during passive gastric distension in cats that includes no change in vascular resistance in some organs and alpha-adrenergic vasoconstriction in others.

Real-time density encoder with three primary colors

A method for pseudocolor encoding of a black-and-white transparency is performed through the simultaneous addition of a direct contrast image, a pseudoreversed image, and a reversed contrast image, each in a different primary color: blue, green, and red, respectively. The physical bases of the method are both specular and diffuse densities, and the method works in real time. The addition of these three color images increases the appreciation range of gray levels in a zone pattern, thereby providing a significant improvement in the information display.

Sympathoadrenal mechanisms in hemodynamic responses to gastric distension in cats

There is presently little information on the efferent mechanisms responsible for the reflex cardiovascular activation during passive gastric distension. Therefore, 40 cats anesthetized with alpha-chloralose were studied with passive gastric balloon distention before and during 1) two repeated gastric distensions, 2) beta-adrenergic blockade with propranolol, 3) alpha-adrenergic blockade with phentolamine, or 4) bilateral adrenalectomy. Before and during each distension mean arterial pressure, heart rate, cardiac output, rate of rise of left ventricular pressure (dP/dt) at 40 mmHg developed pressure and calculated systemic vascular resistance were determined. Repeated gastric distension caused similar hemodynamic responses without tachyphylaxis. beta-Blockade significantly reduced the increase in dP/dt from 893 +/- 362 to 150 +/- 63 mmHg/s. alpha-Blockade significantly altered the changes in mean arterial pressure from 33 +/- 5.0 to -2 +/- 4.7 mmHg and systemic vascular resistance from 0.114 +/- 0.019 to 0.004 +/- 0.031 peripheral resistance units. Bilateral adrenalectomy significantly diminished the contractile response from 525 +/- 107 to 50 +/- 85 mmHg/s but did not significantly alter the pressor and vasoconstrictor responses. We conclude that, during passive gastric distension in cats, the increase in myocardial contractility is mediated by beta-adrenergic-receptor stimulation, whereas the arterial vasoconstrictor and pressor responses are mediated by alpha-adrenergic receptor stimulation. Additionally, during gastric distension a substantial portion of the contractile response is dependent on the integrity of the adrenal glands.