[Laparoscopic assisted percutaneous treatment of inguinal hernia in infants]. / Tratamiento percutáneo asistido por laparoscopia de la hernia inguinal infantil.

INTRODUCTION: Thanks to the generalization of minimally invasive surgery in pediatric patients some classic techniques are being replaced. Inguinal hernia repair may be an example. MATERIAL AND METHODS: We present the technique and our first results in 10 patients treated by percutaneous laparoscopic assisted herniotomy. For this purpose we used an umbilical port, for a 5 mm camera and an optional 2 mm grasper. By laparoscopic guidance we make two inguinal punctures with a 20G needle that introduces a non absorbable suture that crosses the whole inguinal defect and allows it closure by extracorporeal knot tying. RESULTS: The ages ranged between 1 month and 8 years with a median age of 10 months. 50% of the patients were boys. 50% of the patients had previous diagnosis of inguinal bilateral hernia. 30% of patients presented a postoperatory diagnosis different from the previous one. The average time of intervention was 32 minutes in bilateral hernias, and 19 in the unilateral ones. Follow-up time was 6 months without complications. The aesthetic result was ideal. CONCLUSION: Percutaneous laparoscopic assisted herniotomy is an effective, simple and feasible option for inguinal hernia in chidren without a high rate of complications.

[Laparoscopic nephroureterectomy in Wilms tumor]. / Nefroureterectomía laparoscópica en el tumor de Wilms.

INTRODUCTION: Minimally invasive surgery (CMI) for the treatment of malignant tumors in children begins to have a role for selected cases and reaches similar results than open surgery. We show our first two cases of Wilms tumor treated by laparoscopy describing patients and technique. MATERIAL AND METHODS: Three-year-old girl with macroscopic hematuria is diagnosed of 8 cm mass in the left kidney suggesting Wilms tumor. After 4 weeks of chemotherapy she went under laparoscopic nephroureterectomy. The histological result was Wilms tumor. Chemotherapy was completed seven more months. Five-year-old patient with abdominal pain is diagnosed of renal right mass suggesting Wilms tumor. After 4 weeks of chemotherapy the laparoscopic nephroureterectomy was performed. The histological result was Wilms tumor. Treatment was completes with postoperatory chemotherapy. RESULTS: After 1 year follow-up both patients have clinical and radiological absence of disease. CONCLUSION: The CMI in selected cases of Wilms tumor fulfills successfully the aims of the surgical treatment.

Carotid glomus in childhood: presentation of a clinical case. / Glomus carotídeo en la infancia. Presentación de un caso clínico.

INTRODUCTION: Carotid glomus is an exceptional extra-adrenal paraganglioma in childhood originating at the carotid body. Only 3% of paragangliomas occur in the head and the neck. Familial forms, associated with Succinate Dehydrogenase (SDH) gene mutations, account for 10% of cases, the proportion being higher in childhood. They are benign in 95% of patients, but they can extend to both carotids. Treatment is surgical with or without previous embolization. Metastasis is rare and associated with malignant cases, which are limited. CLINICAL CASE: 8-year-old patient with a cervical mass originating 4 months ago and normal serum levels. Regarding family history, she had an aunt who underwent cervical surgery. Ultrasound examination demonstrated a greatly vascularized hypoechoic mass most likely related to carotid glomus. Full surgical resection without embolization was decided upon, which proved uneventful. The genetic study was positive for SDH gene mutation. CONCLUSION: Carotid glomus in childhood should be considered as a differential diagnosis in cervical masses. Surgical treatment without previous embolization represents a safe therapeutic option in selected cases.

INTRODUCCION: El glomus carotídeo es un paraganglioma extraadrenal, excepcional en la infancia, cuyo origen es el cuerpo carotídeo. Solo el 3% de los paragangliomas se presentan en cabeza y cuello. Existe un 10% de formas familiares asociadas a mutaciones en el gen de la succinato deshidrogenasa (SDH), porcentaje que es mayor en la infancia. Son tumores benignos en un 95% de los pacientes, pero pueden afectar por extensión a ambas carótidas. Su tratamiento es quirúrgico con o sin embolización previa. Las metástasis son raras y están asociadas a los escasos casos de malignidad. CASO CLINICO: Paciente de 8 años de edad con masa cervical de 4 meses de evolución, serologías normales. Como antecedente destaca una tía sometida a cirugía cervical. Ecográficamente se objetiva masa hipoecoica muy vascularizada en probable relación con glomus carotídeo. Se decide resección quirúrgica sin embolización que resulta completa y sin incidencias. Estudio genético positivo para la mutación en el gen de la SDH. CONCLUSION: El glomus carotídeo en la infancia ha de ser tenido en cuenta como diagnóstico diferencial en masas cervicales. El tratamiento quirúrgico sin embolización previa es una opción terapéutica segura en casos seleccionados.

[Role of alpha antagonists in uncoordinated micturition syndrome in childhood]. / Papel de los alfa-antagonistas en el síndrome de micción no coordinada en la infancia.

INTRODUCTION: Dysfunctional voiding syndrome in children is characterized by a pattern of dysfunctional bladder emptying due to an active contraction of the external sphincter during micturition. Diagnosis is based on electromyographic and flowmetry results. The treatment is focused on relaxing the external sphincter during micturition where biofeedback is the treatment of choice. By the moment there are still centres without this possibility, alpha blockers are an alternative. OBJECTIVE: To determine the efficacy of alpha blockers as an alternative to biofeedback as a therapeutic possibility. MATERIAL AND METHODS: We included a total of 17 children with dysfunctional voiding syndrome and carried out a retrospective study. We registered age, symptoms at diagnosis, presence of associated urologic problems, flowmetry results pre and post-treatment, type of treatment used and its effectiveness comparing patients treated with alpha blockers and those who are starting to deal with biofeedback. RESULTS: There were 12 girls and 5 boys. The mean age at diagnosis was 4.9 years old, 88% of these children related enuresis, diurnal urinary incontinence and urgency, 57% of them had also urinary infections, 63% constipation, 36% had psychosocial problems. Ten patients were treated with alpha-antagonists: 6 with Tamsulosin and 4 with Doxazosin. They followed this treatment an average of 5.8 months, range between 2 and 12 months. Five patients were treated with biofeedback. All cases had an abnormal pelvic electromyography. Patients treated with alpha-blockers achieved a 70% of electromyographic improvement with a 70% of recurrence. In children treated with biofeedback we got improvement in 80% with no recurrence. After alpha blocker therapy, maximum flow rates and average flow values were better but not statistically significant, this difference was significant with biofeedback. A patient treated with Tamsulosin left treatment due to hypotension, 2 patients left Doxazosin because of dizziness. CONCLUSIONS: Alpha-blockers are effective in the treatment of dysfunctional voiding syndrome with a high percentage of recurrence. They can be an alternative to biofeedback but this one is the effective and definitive treatment.

Deleterious versus neuroprotective effect of metabolic inhibition after traumatic spinal cord injury.

STUDY DESIGN: This work is an experimental and prospective study in adult, female, Long-Evans rats. OBJECTIVES: The aim of this study was to probe the effect of metabolic inhibition after an acute traumatic spinal cord injury (TSCI) using a standardized contusion model (NYU impactor) to know whether the metabolic inhibition is a 'secondary mechanism of injury' or a mechanism of protection. SETTING: All experimental procedures were carried out in the Mexico City. METHODS: Animals were divided into five groups: one sham and four with TSCI, including no treatment, rotenone (inhibitor of mitochondrial complex I), sodium azide (inhibitor of mitochondrial complex IV) and pyrophosphate of thiamine or non-degradable cocarboxylase as a metabolic reactivator. RESULTS: After TSCI, the metabolic inhibition with sodium azide treatment diminished the lipid peroxidation process (malondialdehyde levels by spectrophotometric procedures) and the damage to the spinal cord tissue (morphometric analysis), and increased the activity of creatine kinase and lactate dehydrogenase enzymes (P<0.05) (measured by spectrophotometric procedures 24 h after TSCI as well as after the functional recovery of the hind limb (evaluated weekly for 2 months by the BBB (Basso, Beattie and Bresnahan) scale)) when compared with the TSCI group without treatment. CONCLUSION: The results show that the partial and transitory inhibition of the aerobic metabolism after an acute TSCI could be a self-protection mechanism instead of being a 'secondary mechanism of injury'.

[Multilayer repair of palatal fistula with an interpositional collagen matrix]. / Reparación multicapa de la fístula palatina con interposición de matriz de colágeno.

OBJECTIVE: Palatal fistula after the repair of cleft palate appears in 7.7-35% of patients. We present two cases of palatal fistula, detailing a multi-layer repair with an interpositional collagen graft. MATERIAL AND METHODS: Patient 1: girl with a cleft palate operated using a Furlow technique. A reintervention was performed due to a Pittsburgh type III fistula. Patient 2: male with cleft palate operated using a Furlow technique. A reintervention was performed due to a type V fistula. RESULTS: We used a multilayer repair with a local rotational flap and the interposition of a collagen matrix between the nasal and oral layers. The suture was reinforced with a fibrin hemostatic adhesive. No recurrence of the fistula after 2 years. CONCLUSIONS: The three-layer closure is simple, safe, effective and avoids refistulizations. Interpositional grafts of a resorbable collagen membrane provide a "scaffold" for tissue growth, revascularization and epithelialization of the mucosa.

OBJETIVO: La fístula palatina tras la reparación del paladar fisurado aparece en un 7,7-35% de pacientes. Presentamos dos casos de fístula palatina, detallando la técnica de reparación multicapa con injerto interposicional de colágeno. MATERIAL Y METODOS: Paciente 1: niña con fisura de paladar blando, operada mediante técnica de Furlow. Se programa reintervención por fístula secundaria tipo III de Pittsburgh. Paciente 2: varón con fisura de paladar blando, operado mediante técnica de Furlow. Se programa reintervención por fístula secundaria tipo V. RESULTADOS: Reparación multicapa mediante flap rotacional y matriz de colágeno entre las capas nasal y oral. Refuerzo con adhesivo hemostático de fibrina. Ausencia de recidiva tras 2 años de seguimiento. CONCLUSIONES: El cierre en tres capas es sencillo y efectivo a la hora de evitar refistulizaciones. Los injertos interposicionales de membrana reabsorbible de colágeno proporcionan un "andamio" para el crecimiento de los tejidos, revascularización y epitelialización de la mucosa.

The LMS method and weight and height centiles in Jujuy (Argentina) children.

Human growth and its resulting patterns display a great inter- and intra-population heterogeneity that reflects the quality of life, health and nutritional condition of populations. The aim of this work was to expand the knowledge about the growth of Jujenean children by statistical procedures that graphically express the relation of anthropometric variables to age and allow their comparison with specific references. Anthropometric data came from 9092 children (0-5 years) from various localities of Jujuy province (northwest Argentina) located at 1200 m above sea level (ma.s.l.). The centiles of weight for age (W/A) and height for age (H/A) were obtained by the LMS method using maximum penalized likelihood. A statistical and graphic comparison was made with the corresponding Centers for Disease Control and Prevention (CDC) and World Health Organization (WHO) centile references. In general, estimated centiles were lower than those in both references. Discrepancies for H/A in comparison with the CDC reference ranged between 1.09+/-0.59% and 1.66+/-0.34%, and for W/A between 1.82+/-1.56% and 3.36+/-1.4%. In comparison with the WHO reference, discrepancies ranged from 1.38+/-0.65% to 1.87+/-0.41% for H/A, and from 1.12+/-1.28% to 2.74+/-1.49% for W/A. Centile discrepancies were attributed to the characteristics of early childhood feeding and the interaction of a set of biological and mesological factors that the Jujenean population is exposed to. Growth and nutritional conditions of this population should be evaluated with the WHO reference, for it reflects the recent growth pattern of biologically and culturally healthy children raised in favourable conditions, a pattern that also reflects that of Jujenean children.

Risk of bursitis and other injuries and dysfunctions of the shoulder following vaccinations.

While vaccination injection site adverse reactions are usually mild and transient in nature, several cases of bursitis and other shoulder injuries have been reported in the medical literature. However, these lesions are not included in vaccine label inserts. To identify the characteristics of post-vaccination shoulder injuries and those of patients and involved vaccines, as well as their potential causes, a systematic review of the cases of vaccination-related bursitis and other shoulder injuries reported in the literature and notified to the Spanish Pharmacovigilance System database (FEDRA) have been conducted. We found 45 cases of bursitis and other shoulder injuries that appeared following the vaccine intramuscular injection given into the deltoid muscle (37 from the systematic review of the literature, and 8 from the scrutiny in the Spanish Pharmacovigilance System database, FEDRA). All the patients were adult, 71.1% females, with a mean and median age of 53.6years (range: 22-89). The most frequently involved vaccines were influenza and pneumococcal vaccines, respectively; followed by diphtheria-tetanus-pertussis, diphtheria-tetanus toxoid, human papillomavirus, and hepatitis A vaccines. The most frequent shoulder lesion was bursitis. Most of patients required medical care due to severe local pain and arm mobility restriction. In a majority of cases, symptoms started 48h post vaccination. Subdeltoid or subacromial bursitis and other shoulder lesions may be more common than suspected. Such lesions predominantly affect women. The cause may be related to antigens or adjuvants contained in the vaccines that would trigger an immune or inflammatory response. However, they are more likely to be the consequence of a poor injection technique (site, angle, needle size, and failure to take into account patient's characteristics, i. e., sex, body weight, and physical constitution). Therefore, vaccination-related shoulder injuries would be amenable to prevention.

Novel display of knotted DNA molecules by two-dimensional gel electrophoresis.

We describe a two-dimensional agarose gel electrophoresis procedure that improves the resolution of knotted DNA molecules. The first gel dimension is run at low voltage, and DNA knots migrate according to their compactness. The second gel dimension is run at high voltage, and DNA knots migrate according to other physical parameters such as shape and flexibility. In comparison with one-dimensional gel electrophoresis, this procedure segregates the knotted DNA molecules from other unknotted forms of DNA, and partially resolves populations of knots that have the same number of crossings. The two-dimensional display may allow quantitative and qualitative characterization of different types of DNA knots simply by gel velocity.

[Geographic variability in prescribing antibiotics in the pediatric population of Castille and León during 2001-2005]. / Variabilidad geográfica de la prescripción de antibióticos en la población pediátrica de Castilla y León durante los años 2001 a 2005.

The aim of this study was to determine if there were differences in the antibiotic consumption among the pediatric population of the eleven Primary Health Care centers in the Community of Castilla Leon during the years 2001-2005 and to analyze the possible causes. Data of non-hospital antibiotic consumption in the pediatric population provided the amount of antibiotics billed in the Health Service of the area of Castilla and Leon (central region of Spain). The data was analyzed according to the Anatomic Therapeutic Chemical Classification System (ATC) and expressed as defined daily doses per 1000 inhabitants per day (DID). There were statistically significant differences in the use of antibiotics, varying 8.3 DID between the area with the highest rate (24.86 DID in Leon) and the area with the lowest rate (16.56 DID in Soria). The temporal fluctuations were great and varied especially in Segovia. The pattern of prescribing also varied. The use of penicillin in combination with beta-lacatamase inhibitors varied by a factor of almost three times between Burgos and Segovia. Segovia showed the best management in antibiotic prescriptions with data showing low consumption based on prescribing recommendations. Data from Soria showed low consumption but patterns of misuse in regard to protocols and prescribing. There was wide quantitative and qualitative variability of antibiotic use among the primary health care centers in the region of Castilla and Leon. More detailed studies by age groups, welfare pressure and indication are needed to better understand the determinants of antibiotic use in children.

Remission of systematic lupus erythematosus.

The occurrence and characteristics of remissions in patients with systematic lupus erythematosus (SLE) have not been determined. We therefore studied this in a cohort of 667 patients and found that 156 patients had achieved at least 1 period of 1 year or more of treatment-free clinical remission. This represents an incidence density of 0.028 new cases/person/year. Remission occurred within the first 2 years of disease in 62 patients. The mean duration of first remission was 4.6 years (range, 1-21 yr), and 81 patients were still in the initial remission up until cutoff time. Half of the remaining 75 patients who flared after achieving remission have not entered again in remission. Twenty-six of the 38 patients who did remained in remission, and the remaining 12 had subsequent flares and remissions. Treatment-free remission accounted for a mean of 5.8 years, corresponding to half the time of follow-up. Remission was not limited to patients with mild disease: at least 41 patients achieved remission despite renal involvement, 19 had had neuropsychiatric lupus, 15 had had thrombocytopenia, and 8 had had hemolytic anemia. We also found that the longer the time lapse between the initial manifestation and the diagnosis of SLE, the less likely it was for a patient to enter into remission. There was a continuous increase in likelihood of achieving a first remission from the beginning of disease up to 30 years of disease duration, when it reached 70%. Patients who achieved remission had increased survival, independently of the effect of other disease manifestations that cause increased mortality. We conclude that a significant proportion of patients with SLE, including those with severe organ involvement, may become symptom-free and in need of no more medication, perhaps indefinitely. Our findings support the notion that, in general, SLE is a more benign disease than previously considered.

Decrease in serum antiphospholipid antibody levels upon development of nephrotic syndrome in patients with systemic lupus erythematosus: relationship to urinary loss of IgG and other factors.

PURPOSE: Having observed a decrease in antiphospholipid antibodies (aPL) upon the development of nephrotic syndrome, as well as a negative association between nephrotic syndrome and secondary antiphospholipid syndrome, in patients with systemic lupus erythematosus (SLE), we sought to determine if this could be due to urinary loss of aPL and/or other factors. SUBJECTS AND METHODS: IgG and IgM aPL as well as other autoantibodies were studied by enzyme-linked immunosorbent assay with cardiolipin as antigen in serum and urine from six patients with SLE who had elevated serum aPL levels and developed nephrotic syndrome (cases). For controls, we studied: (1) three SLE patients with nephrotic syndrome but low aPL levels; (2) three patients with non-SLE nephrotic syndrome; (3) three SLE patients with high-titer aPL but no proteinuria; and (4) 10 healthy volunteers. RESULTS: We found urinary IgG, but no IgM, aPL in all cases and in one control from Group 2. Serum IgG aPL had gradually decreased after the development of nephrotic syndrome and had become normal. IgM aPL had also decreased in the four patients who had elevated levels, having reached normal levels at the time of the study in two. There was an apparent correlation between serum and urine IgG aPL levels but not between urinary IgG aPL and total proteinuria. By Farr's method, we found no urinary anti-DNA despite high serum titers in three cases. The two cases and one of the controls in Group 1 who had serum antibodies to extractable antigens also had these antibodies in the urine. CONCLUSION: Urinary loss of IgG aPL during nephrotic syndrome does not completely explain the reduction in serum aPL, since IgM also decreases. There could also be decreased synthesis and/or increased catabolism of immunoglobulins.

Quantitative comparisons of continuous and pulsed low dose rate regimens in a model late-effect system.

PURPOSE: There is increasing interest and usage of pulsed low dose rate (PDR) brachytherapy, in which a single source is shuttled through the catheters of an implant, typically for about 10 min each hour. This study was designed to compare the late effects produced in various PDR regimens with those from the corresponding continuous low dose rate (CLDR) regimens. METHODS AND MATERIALS: A model late-responding system was used, namely, cataract induction in the rat lens. This system has the advantage of being highly quantifiable. The rats eyes were exposed to a total dose of 15 Gy either continuously over 24 h, or with three different PDR regimens, all with the same total dose and overall time. We addressed three questions: (a) are late effects increased when a CLDR regimen is replaced with 10-min pulses repeated every hour? (b) Are late effects increased if hourly 10-min pulses are replaced with 10-min pulses repeated every 4 h? (c) Are late effects increased if 10-min pulses are replaced with 100-s pulses? RESULTS: We found that the four regimens under test, continuous, 10-min pulses each hour, 10-min pulses every 4 h, and 100-s pulses every hour, showed no significant differences in cataractogenic potential, as estimated with the Wilcoxon-Gehan test. Power tests indicated that the experimental design was adequate to detect relatively small differences in cataractogenicity between regimens. CONCLUSIONS: The equality of late effects from CLDR and PDR in these experiments must imply that sublethal damage repair is quite slow in this model late-responding system, in agreement with trends observed in the clinic for sublethal damage repair of late sequelae. Such trends would suggest that PDR is unlikely to produce significantly worse late effects than the corresponding CLDR regimen, which is in agreement with early clinical data using PDR. Caution, however, is strongly recommended.

Experimental model of light focusing of the peripheral cornea.

PURPOSE: Epidemiologic studies have shown that the onset of cortical cataract occurs primarily in the inferonasal human lens and that the incidence of cortical cataract is correlated with ultraviolet light. Ray tracing analysis has suggested that the peripheral cornea concentrates light on the opposite peripheral lens and that the nose and orbit block peripheral light, except temporally, resulting in a relative concentration of light on the inferonasal lens. Studies were performed to test these theories. METHODS: A model cornea and anterior chamber, set on a disc of light-sensitive paper, was placed in the orbit of a human skull coated with wax to simulate soft tissue. The "eye" was exposed to summer sunlight at various times of day, with and without sunglasses. Discs from the different experimental groups were scanned, and the digitized images were analyzed densitometrically using image analysis software. RESULTS: With the head upright, the inferonasal section of the disc exhibited the most intense exposure under all lighting conditions. Sunglasses decreased the intensity of overall light exposure but did not eliminate the inferonasal bias. Only blocking the temple eliminated this effect. CONCLUSIONS: This model supports the idea that the peripheral cornea focuses light on the inferonasal portion of the human lens. These results may explain the correlation between light and the location of cortical cataract.

Preliminary classification criteria for the antiphospholipid syndrome within systemic lupus erythematosus.

Ten percent of 667 consecutive systemic lupus erythematosus (SLE) patients were considered to have definite antiphospholipid syndrome (aPLS) because they had two or more antiphospholipid (aPL)-related clinical manifestations and aPL titers more than 5 SD above the mean of normal controls. Another 14% had either one aPL-related manifestation but high titers of the antibody or two manifestations and low aPL titers (probable aPLS). One fourth of the patients had no manifestations but high titers, one manifestation and low titers, or two or more manifestations and negative aPL titers ("doubtful" aPLS); the other half were considered negative for aPLS. In patients with high-titer aPL, the number of aPL-related manifestations was influenced by disease duration and number of pregnancies, indicating potential mobility of category with time or with risk of recurrent pregnancy loss. Patients with two or more manifestations but variable aPL levels differed in immunosuppressive treatment and in the number of times they had been tested, indicating potential mobility of category with lower treatment and/or further aPL testing. Patients with definite aPLS had increased risk of cutaneous vasculitis, peripheral neuropathy, seizures, psychosis, transient ischemic attacks, and leukopenia. In 11 of 52 SLE patients with definite aPLS the initial manifestation was related to aPL, and in 16 it concurred with an unrelated one. Only two patients fulfilled criteria for aPLS before having other evidence of SLE. The authors conclude that aPLS occurring within SLE is part of the disease rather than an associated condition and propose the use of definite and probable classification categories. These criteria, with appropriate follow-up and clinical and serological exclusion clauses for potential primary conditions, could also be applied to primary aPLS.

Messenger RNAs for trk and the low-affinity NGF receptor in rat basal forebrain.

Nerve growth factor (NGF) acts by binding to specific sets of neurons. Low-affinity binding (Kd of 10(-9) M) is mediated via a 75 kDa glycoprotein (LNGFR). Recently, a 140 kDa tyrosine protein kinase encoded by the proto-oncogene trk has been found to bind NGF with high affinity (Kd of 10(-11) M) and to evoke neurotrophic responses. In addition, the related trkB protein and the LNGFR have been shown to bind brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) with an affinity of Kd 10(-9) M. We demonstrate the distribution of mRNA encoding the neurotrophin-binding proteins in the forebrain of the 21-day-old Sprague-Dawley rat by in-situ hybridization. Expression of trk and LNGFR mRNA showed co-localization and was restricted to the medial septal nucleus and the nucleus of Broca's diagonal band, suggesting a receptor function in these cells for both proteins encoded. In contrast, expression of trkB was widely spread in many areas. Thus trkB protein might serve general functions in the forebrain.

Plasmid Transfer Detection in Soil using the Inducible lPR System Fused to Eukaryotic Luciferase Genes.

We report a model system for plasmid transfer analysis using the regulated lambda phage right promoter, lPR, fused to luc and lucOR as reporter genes. We have demonstrated that the systems cI857-lPR::luc and cI857-lPR::lucOR are temperature-inducible in Escherichia coli but not in other Gram-negative bacteria analyzed, enabling detection of luminescence when plasmids were mobilized from E. coli to those Gram-negative backgrounds. Using light for the detection, we have observed plasmid transfer from E. coli harboring RK2 and R388 derived plasmids to Pseudomonas putida KT2440 (co-introduced with donors) and to indigenous microorganisms, in vitro and in nonsterile soil microcosms. The importance of nutrients for an efficient plasmid transfer in nonsterile soil microcosms has been confirmed. When plasmid transfer experiments were carried out into nonsterile soil microcosms, significant populations of indigenous transconjugants arose. This system provides efficient marker genes and avoids the use of antibiotics for the selection of transconjugants.

Neurobiological problems in long-term deep space flights.

Future missions in space may involve long-term travel beyond the magnetic field of the Earth, subjecting astronauts to radiation hazards posed by solar flares and galactic cosmic rays, altered gravitation fields and physiological stress. Thus, it is critical to determine if there will be any reversible or irreversible, detrimental neurological effects from this prolonged exposure to space. A question of particular importance focuses on the long-term effects of the space environment on the central nervous system (CNS) neuroplasticity, with the potential acute and/or delayed effects that such perturbations might entail. Although the short-term effects of microgravity on neural control were studied on previous low earth orbit missions, the late consequences of stress in space, microgravity and space radiation have not been addressed sufficiently at the molecular, cellular and tissue levels. The possibility that space flight factors can interact influencing the neuroplastic response in the CNS looms critical issue not only to understand the ontogeny of the CNS and its functional integrity, but also, ultimately the performance of astronauts in extended space forays. The purpose of this paper is to review the neurobiological modifications that occur in the CNS exposed to the space environment, and its potential consequences for extended deep space flight.

In vitro neurotoxic effects of 1 GeV/n iron particles assessed in retinal explants.

The heavy ion component of the cosmic radiation remains problematic to the assessment of risk in manned space flight. The biological effectiveness of HZE particles has yet to be established, particularly with regard to nervous tissue. Using heavy ions accelerated at the AGS of Brookhaven National Laboratory, we study the neurotoxic effects of iron particles. We exposed retinal explants, taken from chick embryos, to determine the dose response relationships for neurite outgrowth. Morphometric techniques were used to evaluate the in vitro effects of 1 GeV/a iron particles (LET 148 keV/micrometer). Iron particles produced a dose-dependent reduction of neurite outgrowth with a maximal effect achieved with a dose of 100 cGy. Doses as low as 10-50 cGy were able to induce reductions of the neurite outgrowth as compared to the control group. Neurite generation is a more sensitive parameter than neurite elongation, suggesting different mechanism of radiation damage in our model. These results showed that low doses/fluences of iron particles could impair the retinal ganglion cells' capacity to generate neurites indicating the highly neurotoxic capability of this heavy charged particle.