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Biomedical subjects

G Koren

Publications and source records attributed to G Koren.

At least 37 records · Page 2Linked to original sources

Long-term restitution of 4-aminopyridine-sensitive currents in Kv1DN ventricular myocytes using adeno-associated virus-mediated delivery of Kv1.5.

Overexpression of a dominant-negative truncated Kv1.1 (Kv1DN) polypeptide in the mouse heart resulted in marked attenuation of a 4-aminopyridine (4-AP)-sensitive current, I(K,slow1). We used recombinant adeno-associated virus (rAAV) as a vector for direct delivery of Kv1.5 into the mouse myocardium in order to normalize the action potential duration (APD) 6 months after injection. The injection of rAAV-Kv1.5 reconstituted the 4-AP-sensitive outward potassium currents, shortened the APD, and eliminated spontaneous early afterdepolarizations. Immunoblots detected the FL-Kv1.5 polypeptides only in rAAV-Kv1.5-infected hearts. These data demonstrate long-term expression of 4-AP-sensitive potassium currents in ventricular myocytes by gene transfer using rAAV vector encodes Kv1.5.

4-Aminopyridine↗

In vitro cytoprotective activity of squalene on a bone marrow versus neuroblastoma model of cisplatin-induced toxicity. implications in cancer chemotherapy.

The development of a non-toxic selective cytoprotective agent that preferentially protects normal tissues from chemotherapy toxicity, without protecting malignant tissues, is a major challenge in cancer chemotherapy research. The available cytoprotective agents are either toxic or lack selective cytoprotective activity. Here, we report the in vitro selective cytoprotective activity of squalene, an isoprenoid molecule with antioxidant properties. Normal human bone marrow (BM) derived colony-forming unit (CFU) growth was increased by squalene in a dose-dependent manner. Squalene (12.5-25 microM) treatment significantly protected the CFUs from cisplatin-induced toxicity; the protective effect was equivalent to reduced glutathione (GSH), a known cytoprotective agent. Squalene also increased the long-term survival of cisplatin-treated 4-week-old CFUs. Cisplatin-induced apoptosis of CFUs as measured by the TUNEL assay was reduced by squalene. To examine the squalene-induced protection of tumours, several neuroblastoma cell lines, including five MYCN-amplified cell lines, were grown in monolayers, as well as in anchorage-independent cultures, in the presence of squalene and cisplatin. Squalene did not protect the neuroblastoma (NBL) cell lines from cisplatin-induced toxicity. In addition, squalene did not protect the NBL cells from carboplatin, cyclophosphamide, etoposide and doxorubicin-induced toxicity. In conclusion, our results suggest that squalene has a selective in vitro cytoprotective effect on BM-derived haematopoietic stem cells that is equipotent to GSH.

Antineoplastic Agents↗

Comparison of meconium and neonatal hair analysis for detection of gestational exposure to drugs of abuse.

BACKGROUND: Meconium and hair are two biological markers of in utero exposure to illicit drugs. OBJECTIVE: To compare the sensitivity of the two tests for different drugs. SETTING: Motherisk laboratory which tests in utero drug exposure in Toronto. METHODS: Cocaine, benzoylecgonine, opiates, cannabis, benzodiazepines, methadone, and barbiturates were measured in pairs of hair and meconium samples from the same neonates. RESULTS: Meconium was marginally more sensitive than neonatal hair for detection of cocaine and cannabis, possibly because it may detect second trimester exposure whereas hair grows only during the third trimester of pregnancy. There was a significant correlation between hair and meconium concentrations of cocaine, cannabis, and opiates. CONCLUSION: In cases of clinical suspicion and a negative neonatal urine test, both meconium and hair are effective biological markers of in utero illicit drug exposure. Meconium may be more sensitive, but neonatal hair is available for three months whereas meconium is available for only one or two days. In contrast, the use of meconium, being a discarded material, is more acceptable to some parents than hair testing, which entails cutting scalp hair from the newborn.

Cannabis↗

Nausea and vomiting in pregnancy: results of a survey that identified interventions used by women to alleviate their symptoms.

Nausea and vomiting of pregnancy (NVP) affects most pregnant women. There are safe and effective treatments available; however, most women choose to avoid pharmacological therapies and try lifestyle and dietary changes to treat their condition. To date, no attempt has been made to quantify women's experience with a variety of interventions. This study aims to identify factors commonly reported by women that alleviate their symptoms of NVP. Five hundred women with NVP, calling a pregnancy healthline between February 1996 and July 1999, completed a questionnaire where they were asked to rate which of 21 factors helped and to what extent each factor helped to improve their NVP symptoms. For each item, the 'frequency' (percentage of women who indicated that item as an improvement) and 'mean importance' (mean importance score of women who indicated that item as an improvement) were multiplied to give the 'overall impact' score. All 500 women reported that dietary and lifestyle changes helped to improve their NVP symptoms. However, most items were rated low and only 31% of women reported benefit from the use of pharmacological treatment. In conclusion, this study has identified that NVP is a multifaceted condition. Lifestyle changes including validation, supportive counseling and dietary adjustments are important components, that can be used to counsel women with NVP, concomitantly with safe and effective treatment.

Adult↗

The Toronto experience in diagnosing alcohol-related neurodevelopmental disorder: a unique profile of deficits and assets.

BACKGROUND: Fetal alcohol syndrome (FAS), which involves the triad of features reflecting facial dysmorphology, growth retardation and intellectual impairments, encompasses a relatively small proportion of the children affected prenatally by alcohol. Unfortunately, in the absence of facial dysmorphology, the diagnosis is difficult in the majority of children, who are considered to have alcohol-related neurodevelopmental disorder (ARND). Because accepted clinical methods are not pathognomonic, a novel profile approach was used to examine neuropsychological abilities and disabilities to identify children with ARND who do not meet the diagnostic criteria of FAS. OBJECTIVE: To establish a set of criteria, to be validated in future studies, for characterizing the neuropsychological profile of children with ARND. By describing the procedures at this preliminary stage of our work, the goal is to draw attention to this neglected topic and to suggest a model that can be replicated and validated by others, and to provide the first systematic clinical report on diagnosing ARND in Canada. PROCEDURES: On the basis of the literature, parents' descriptions and the authors' own experience with ARND, a profile of neuropsychological characteristics, including both deficits and assets, that are associated with prenatal alcohol exposure was hypothesized. A group of children was then evaluated, mostly adoptees or children in foster care, who were referred for learning and behavioural problems potentially associated with gestational exposure. Their results were submitted to a profile analysis by comparing their deficits and assets according to a list describing a hypothetical ARND profile to determine whether each child fit or did not fit the ARND profile. Groups were compared for background characteristics, FAS symptomatology, and results on specific neuropsychological and behavioural tests. Finally, the characteristics most strongly differentiating the two groups were identified. SETTING: Hospital-based outpatient program. PARTICIPANTS: Fifty-two children aged four to 18 years who were referred for a diagnostic assessment related to suspected or known prenatal alcohol exposure. OUTCOME MEASURES: Each child's assessment results were compared against a list of 21 deficits and six assets by two independent raters. Children with an average of more than 60% deficits and 50% assets were considered to have ARND, while the remainder were not. RESULTS: Twenty-eight children (54%) were assigned to the ARND group and 24 to the non-ARND group. The groups did not differ in physical features or home background characteristics, with the exception of higher parental intelligence quotient in the non-ARND group. The ARND group was more likely to have repeated a grade or received special education and scored lower on standardized measures of intelligence, language and memory abilities. Frequency of behaviour or social problems were equivalent in both groups. CONCLUSIONS: A profile approach used to identify children with ARND discriminates problems in neuropsychological but not behavioural domains. Because elevated scores on behavioural tasks in both ARND and non-ARND groups were clinically significant, more research is needed to identify what behavioural problems are unique to children with ARND compared with other clinic-referred children.

Adolescent↗

Neurodevelopment of children exposed in utero to treatment of maternal malignancy.

Cancer is the second most common cause of death during the reproductive years, complicating approximately 1/1000 pregnancies. The occurrence of cancer during gestation is likely to increase as a result of a woman's tendency to delay childbearing. Improved diagnostic techniques for malignancies increases detection of cancer during pregnancy. Malignant conditions during gestation are believed to be associated with an increase in poor perinatal and fetal outcomes that are often due to maternal treatment. Physicians should weigh the benefits of treatment against the risks of fetal exposure. To date, most reports have focused on morphologic observations made very close to the time of delivery with little data collected on children's long-term neurodevelopment following in utero exposure to malignancy and treatment. Because the brain differentiates throughout pregnancy and in early postnatal life, damage may occur even after first trimester exposure. The possible delayed effects of treatment on a child's neurological, intellectual and behavioural functioning have never been systematically evaluated. The goal of this report was to summarize all related issues into one review to facilitate both practitioners' and patients' access to known data on fetal risks and safety.

Child↗

Ocular toxicity and antenatal exposure to chloroquine or hydroxychloroquine for rheumatic diseases.

Chronic use of chloroquine and hydroxychloroquine inthe treatment of rheumatic disease carries a small risk of sight-threatening pigmentary retinopathy. To obtain safety data for its use in pregnancy, we did ophthalmic examinations in 21 children born to women who took these drugsduring pregnancy. Average daily maternal doses of the two drugs were 317 mg hydroxychloroquine and 332 mg chloroquine. The mean duration of gestational exposure was 7.2 months. No ophthalmic abnormality was detected in these children. Therapeutic use of these drugs during pregnancy may not pose a significant risk of ocular toxicity to offspring.

Antirheumatic Agents↗

Phase I trial of a twice-daily regimen of amifostine with ifosfamide, carboplatin, and etoposide chemotherapy in children with refractory carcinoma.

BACKGROUND: Amifostine protects normal tissues against chemotherapy and radiation-induced toxicity without loss of antitumor effects. Evidence suggests that multiple daily doses of amifostine may improve its cytoprotective effects. The purpose of this study was to assess the dose-limiting toxicities (DLTs) and maximum tolerated dose (MTD) of twice-daily doses of amifostine with ifosfamide, carboplatin, and etoposide (ICE) chemotherapy for children with refractory malignancies and to determine the pharmacokinetic properties of amifostine, WR-1065, and the disulfide metabolites of amifostine. METHODS: Patients with refractory malignancies were treated with amifostine 15 minutes before and 2 hours after chemotherapy with ifosfamide (3 g/m(2) per dose on Days 1 and 2) and carboplatin (635 mg/m(2) on Day 3). Etoposide was administered on Days 1 and 2 (150 mg/m(2)). The starting dose of amifostine was 740 mg/m(2). Pharmacokinetic studies were performed after the first dose of amifostine. RESULTS: Twelve patients received 23 courses of ICE and amifostine. Dose-limiting toxicities for amifostine at 740 mg/m(2) were somnolence and anxiety. The other Grade 3 and 4 toxicities included asymptomatic, reversible hypocalcemia, vomiting, and reversible hypotension. At a dose of 600 mg/m(2), amifostine was well tolerated. Hypocalcemia, due to rapid, transient suppression of parathyroid hormone production, required close monitoring and aggressive intravenous calcium supplementation. Pharmacokinetic studies revealed high interpatient variability with rapid plasma clearance of amifostine and WR-1065. The median elimination half-life of amifostine (9.3 minutes) and WR-1065 (15 minutes) was much shorter than the disulfide metabolites (74.4 minutes). CONCLUSIONS: The recommended pediatric dose of amifostine for a twice-daily regimen is 600 mg/m(2) per dose (1200 mg/m(2)/day) with DLTs of anxiety and somnolence, lower than the previously recommended single dose of 1650 mg/m(2).

Adolescent↗

Pregnancy outcome after cyclosporine therapy during pregnancy: a meta-analysis.

BACKGROUND: Cyclosporine (CsA) therapy must often be continued during pregnancy to maintain maternal health in such conditions as organ transplantation and autoimmune disease. This meta-analysis was performed to determine whether CsA exposure during pregnancy is associated with an increased risk of congenital malformations, preterm delivery, or low birthweight. METHODS: Various health science databases were searched to identify relevant articles. Articles selected for inclusion in the study were required to be free of any apparent selection bias and report outcomes in at least 10 newborns exposed to CsA in utero, specifically commenting on the presence or absence of congenital malformations. Article selection and data extraction were performed by two independent reviewers, with adjudication in cases of disagreement. To assess risks of CsA exposure, a summary odds ratio was calculated. Prevalence of malformations was calculated as a rate for all cyclosporine-exposed live births and for the subgroups identified. Ninety-five percent confidence intervals were constructed for both the odds ratio and prevalence rates. RESULTS: Fifteen studies (6 with control groups of transplant without use of cyclosporine; total patients: 410) met the inclusion criteria for major malformations, 10 for preterm delivery (4 with control groups; total patients: 379) and 5 for low birth weight (1 with control groups; total number of patients: 314). The calculated odds ratio of 3.83 for malformations did not achieve statistical significance (CI 0.75-19.6). The overall prevalence of major malformations in the study population (4.1%) also did not vary substantially from that reported in the general population. OR for prematurity [1.52 (CI 1.00-2.32)] did not reach statistical significance although the overall prevalence rate was 56.3%. The OR for low birth weight [1.5 (CI 0.95-2.44 based on 1 study)]. CONCLUSIONS: CsA does not appear to be a major human teratogen. It may be associated with increased rates of prematurity. More research is needed to evaluate whether cyclosporine increases teratogenic risk.

Congenital Abnormalities↗

Piracetam therapy does not enhance cognitive functioning in children with down syndrome.

BACKGROUND: Piracetam is widely used as a purported means of improving cognitive function in children with Down syndrome. Its efficacy, however, has not been rigorously assessed. OBJECTIVE: To determine whether 4 months of piracetam therapy (80-100 mg/kg per day) enhances cognitive function in children with Down syndrome. DESIGN: A randomized, double-blind, placebo-controlled crossover study. PARTICIPANTS AND METHODS: Twenty-five children with Down syndrome (aged 6.5-13 years) and their caregivers participated. After undergoing a baseline cognitive assessment, children were randomly assigned to 1 of 2 treatment groups: piracetam-placebo or placebo-piracetam. MAIN OUTCOME MEASURE: The difference in performance while taking piracetam vs while taking placebo on tests assessing a wide range of cognitive functions, including attention, learning, and memory. RESULTS: Eighteen children completed the study, 4 withdrew, and 3 were excluded at baseline. Piracetam therapy did not significantly improve cognitive performance over placebo use but was associated with central nervous system stimulatory effects in 7 children: aggressiveness (n = 4), agitation or irritability (n = 2), sexual arousal (n = 2), poor sleep (n = 1), and decreased appetite (n = 1). CONCLUSION: Piracetam therapy did not enhance cognition or behavior but was associated with adverse effects.

Adolescent↗

Effects of maternal occupational exposure to organic solvents on offspring visual functioning: a prospective controlled study.

BACKGROUND: Previous studies in adults and animals with high level exposure to organic solvents suggested impairments in visual functioning. The objective of this pilot study was to examine the effects of maternal occupational exposure to organic solvents during pregnancy on offspring color vision and visual acuity, the development of which may be especially vulnerable to organic solvent exposure. METHODS: We conducted a prospective cohort study of 32 offspring of women who were exposed occupationally to organic solvents during pregnancy compared with 27 nonexposed children. Monocular and binocular color vision and visual acuity were assessed using the Minimalist Test and the Cardiff Cards, respectively. Children with known hereditary color vision loss were excluded. RESULTS: Solvent-exposed children had significantly higher error scores on red-green and blue-yellow color discrimination, as well as poorer visual acuity compared with the control group. Exposure index (an estimated measure of exposure intensity) was not significantly related to color discrimination or visual acuity score. Despite excluding all children with a known family history of color vision loss, clinical red-green color vision loss was found among 3 of the 32 exposed children compared with none of the matched controls. CONCLUSIONS: These preliminary findings suggest that occupational exposure to organic solvents during pregnancy is associated with an increased risk of color vision and visual acuity impairment in offspring. The importance of routine visual function screening in risk assessment after prenatal exposure to chemicals warrants further attention.

Adult↗

Young age and the risk for ifosfamide-induced nephrotoxicity: a critical review of two opposing studies.

Ifosfamide has been in use as an effective antineoplastic agent for solid tumors in both children and adults since the late 1960s. Although some adverse effects (e.g. hemorrhagic cystitis) can be overcome by the co-administration of 2-mercaptoethanesulfonate (MESNA), others such as nephrotoxicity cannot. There is a consensus that factors such as the cumulative dose of ifosfamide and concomitant cisplatin administration may influence not only the incidence but also the severity of ifosfamide-induced renal toxicity. Several preliminary studies suggested young age as a risk factor for nephrotoxicity; however, there is little agreement on this. The reasons for this uncertainty may include sample size, study design, dose and differences in renal function assessment. In this review we examine the two largest cohort studies conducted in pediatric patients. One study suggests that ifosfamide-induced renal toxicity is age- related, whereas analysis of the other failed to show age as an important predictor for ifosfamide-induced renal toxicity. The studies differed in design, end-points of toxicity and concomitant drug therapy. Due to the effectiveness of ifosfamide as an antineoplastic agent, it is important that an understanding of the factors that predispose pediatric patients to ifosfamide-induced nephrotoxicity be obtained.

Aging↗

The generalizability of trial data; a comparison of beta-blocker trial participants with a prospective cohort of women taking beta-blockers in pregnancy.

OBJECTIVE: To evaluate the generalizability of randomized controlled trial (RCT) data to obstetric practice, using the example of beta-blocker therapy. STUDY DESIGN: Descriptive comparison of characteristics of participants, interventions, and outcomes assessed between a meta-analysis of trials of beta-blocker therapy in pregnancy, and a prospective cohort of beta-blocker exposed callers to Motherisk, a Teratology Information Service. RESULTS: 72 women (cohort) and 34 trials with 2474 participants (meta-analysis) were compared. The generalizability of trials was limited by an inadequate description of maternal demographics and indications for beta-blockers, and a focus on the effectiveness of beta-blockers as antihypertensives rather than on reproductive risks. CONCLUSIONS: Some of these limitations could be rectified. Others cannot, such as evaluation of teratogenicity (for ethical reasons) or all indications for a drug (for practical reasons). Reference to observational literature is, and will likely remain, necessary to address the 'harm' side of the therapeutic equation in pregnancy.

Adrenergic beta-Antagonists↗

A novel method for the evaluation of the severity of nausea and vomiting of pregnancy.

UNLABELLED: The symptomatology of nausea and vomiting of pregnancy (NVP) ranges from mild to very severe. The most advanced method to measure the burden of NVP, the Rhode's scores, incorporates physical signs (length and number of episodes of nausea, number and volume of vomits, and number of retching) with measures of distress caused by these symptoms. However, this system has been validated only for symptoms that occurred in the past 12 h, thus obviating its wide clinical use, and particularly its retrospective use. OBJECTIVE: To examine whether the severity of the physical symptoms of NVP correlate with the degree of stress caused by them, and to develop simple scores that can be used clinically. METHODS AND RESULTS: We prospectively scored 283 women with NVP using the Rhode's system. There was excellent and highly significant correlation between the physical symptoms and their degrees of distress. Subsequently, we examined two simple scoring systems, one with three and one with five physical symptoms. Both yielded distribution of severity of NVP not different from the one found with the use of the full Rhode's score. CONCLUSION: A scoring system based on all five physical symptoms, or only on three (length of nausea, number of episodes of nausea and number of vomits) yielded accurate estimates of severity and changes in severity of NVP. Unlike the Rhode's score, this simple method can be used clinically to evaluate the severity and changes in NVP.

Adolescent↗

Impairment of pyruvate dehydrogenase activity by acetaldehyde.

The facial features that are characteristic of fetal alcohol syndrome (FAS) are strikingly similar to those seen in pyruvate dehydrogenase (PDH) deficiency. Furthermore, alcohol-induced central nervous system insult results in midline anomalies such as agenesis of the corpus callosum, which has also been described in several metabolic diseases, including PDH deficiency. The purpose of this work was to examine the effect of acetaldehyde on PDH in vitro. The activity of PDH was measured in the presence of acetaldehyde (10 microM-1 mM) by measuring the formation of the reduced form of nicotinamide-adenine dinucleotide at 340 nm. Pyruvate dehydrogenase was separated by using the sodium dodecyl sulfate-polyacrylamide gel electrophoresis technique after incubation with [1,2-(14)C]-acetaldehyde to detect the formation of covalent adducts autoradiographically. The effect of acetaldehyde on the phosphorylation of the complex was also determined autoradiographically after incubating of PDH with (32)P-adenosine triphosphate. The results of this study show that acetaldehyde impairs PDH activity by a mixed inhibition type mechanism (Kic=62.4+/-25.7 microM, Kiu=225+/-68 microM), which is not a result of the formation of covalent adducts with PDH, nor of a stimulation of phosphorylation or inactivation of the complex. Because PDH levels are low throughout development and that the competition between pyruvate and acetaldehyde may be enhanced due to ethanol-induced lowering of ambient pyruvate concentrations, we conclude that impairment of PDH may have a significant effect on the developing fetus.

Acetaldehyde↗

Evidence based information on drug use during pregnancy: a survey of community pharmacists in three countries.

OBJECTIVE: To evaluate whether community pharmacists provide evidence-based information to women inquiring about specific drug use during pregnancy. DESIGN: A trained female student posing as a surrogate shopper requested information about the relative safety/risks of medications during pregnancy in two scenarios. Forty randomly selected pharmacies were surveyed in the Netherlands, Canada and Iceland, and pharmacists' recommendations were noted. Main outcome measures included the type of information that was provided, its presentation, and the source of information used. RESULTS: A relatively small proportion of pharmacists surveyed, provided evidence-based information regarding the drugs in question. Only 14% referred to current medical literature, while 60% consulted the product monograph. Over 90% of pharmacists referred the client to a physician. CONCLUSIONS: Community pharmacists do not disseminate evidence-based recommendations when counseling women on drug use in pregnancy, and need further education on resources concerning drugs in pregnancy that are currently available.

Adult↗

Cyclosporin A in the treatment of refractory immune thrombocytopenia purpura in children.

Patients with refractory autoimmune thrombocytopenia do not respond to standard therapy with high-dose corticosteroids, intravenous immunoglobulin, and splenectomy. We describe the cases of two patients with refractory autoimmune thrombocytopenia treated with oral cyclosporin A (CsA) to evaluate the efficacy of this alternative therapy. Blood pressure and hepatic and renal function were in the normal range before initiation of treatment. Induction therapy with pulses of high-dose methylprednisolone was used for 3 consecutive days to improve the initial immune suppression. Gradual dose reduction of CsA, according the platelet count, minimized the long-term adverse effects of CsA. Oral CsA with pulses of high-dose methylprednisolone induced remission of the thrombocytopenia. Gradual weaning of CsA over months, according the platelet count, produced no observable adverse effects of the CsA. Rapid dose reduction caused thrombocytopenia, which resolved with higher dosages of CsA. Our cases show the efficacy of CsA for refractory immune thrombocytopenia. This therapeutic option with oral CsA as an additional salvage option may avoid splenectomy and the adverse effects of long-term corticosteroids. Larger clinical investigations are necessary to establish the indications and therapeutic regimen for CsA in immune thrombocytopenia.

Adolescent↗