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Biomedical subjects

S Arndt

Publications and source records attributed to S Arndt.

At least 19 recordsLinked to original sources
PubMed2006

[Ethisorb/Ethisorb durapatch for the transnasal duraplasty procedure?].

BACKGROUND: Defects of the dura in the rhinobasal area can be closed transnasally. Various procedures with autologous or alloplastic material can be chosen. METHOD: From 2001 to 2004, we closed a rhinobasal dura defect with Ethisorb or Ethisorb durapatch in sandwich technique in 8 patients. After smoothing the bone edges, Ethisorb is applied under microscopic or endoscopic view endocranially, extradurally as "underlay" to seal and absorb the liquor pressure pillar. Additionally, another Ethisorb implant as "underlay" is applied extracranially from endonasally as "underlay", and sealed with a further layer of nasal concha mucosa with fibrin glue. RESULTS: All patients were successfully treated with this technique. There were no evidences for persisting rhinoliquorrhoe after the period of wound healing. For hemostasia, a nasal package was applied for compression at the donor site of the inferior nasal concha. The former dura defect was at all times freely accessible in order to be able to recognize a possible new rhinoliquorrhoea early and to prevent a possible congestive secretion with superinfection. DISCUSSION: The material of Ethisorb and Ethisorb durapatch is stiff and can be easily modelled, so it is an alternative as an alloplastic material for endonasal closure of defined substantial defects of the dura with rhinoliquorrhoe.

Adult↗
PubMed2005

[Paralyzed face. Ansa-cervicalis-nervi-hypoglossi].

INTRODUCTION: For 100 years hypoglossal-facial nerve anastomosis (HFA) has been a common surgical procedure for reanimation of paralyzed mimic muscles of the face after axotomy of the facial nerve. However, the denervation and subsequent scarred degeneration of the target muscles of the hypoglossal nerve often results in unfavorable late effects for speech and swallowing. Therefore, the ansa cervicalis nervi hypoglossi-facial nerve anastomosis (ACHFA) can be an alternative to avoid such late effects. As a branch of the hypoglossal nerve the ansa cervicalis innervates the infrahyoidal muscles. Neck dissection surgery proved that resection of the ansa cervicalis causes no side effects for swallowing because of several nerve anastomoses to the cervical plexus. PATIENTS AND METHOD: We compared our clinical results of eight cases following a delayed ACHFA with our own experiences after HFA and results from the literature. RESULTS: We found a reanimation rate lower than usually seen after HFA only in the target muscles of the forehead. This may be caused by a reduced neuronal plasticity of the ansa cervicalis. However, in the target muscles of the other two facial nerve branches we observed the same good results one would expect after HFA. There were no late side effects for swallowing and speech though.

Adult↗
PubMed2004

Imiglucerase low-dose therapy for paediatric Gaucher disease--a long-term cohort study.

BACKGROUND: Gaucher disease is the most common lysosomal storage disorder caused by the insufficiency of the lysosomal enzyme, glucocerebrosidase. This deficiency results in absent or inefficient conversion of glucocerebroside (a membrane lipid) to ceramide and glucose. Accumulation of glucocerebroside occurs primarily in macrophage lysosomes (i.e. monocytes and macrophages) during phagocytic degradation of red blood cells. Clinical symptoms arise due to the displacement of normal cells by lipid-engorged Gaucher cells. Enzyme replacement therapy (ERT) targets the macrophage system and has been shown to be successful in the treatment of type 1 Gaucher disease in adults and children. ERT (60 U/kg) every 2 weeks decreases and often reverses organomegaly and haematological complications and improves quality of life for patients with type 1 Gaucher disease. The present study describes the course of 9 paediatric patients followed up for 2 - 10 years receiving low-dose imiglucerase therapy (+/- 10 U/kg every 2 weeks) for moderate to severe type 1 Gaucher disease. OBJECTIVES: To evaluate the efficacy of low-dose imiglucerase therapy in paediatric Gaucher disease. SUBJECTS AND METHODS: Data were recorded at a single centre for 9 paediatric patients. Assessment of response included serial measurements of haemoglobin (Hb) concentrations, platelet count, angiotensin-converting enzyme (ACE) and total acid phosphatase (TAP) levels. Growth was assessed by serial determinations of body weight and height, plotted against standard growth charts. Organ size (liver and spleen) was measured clinically and also radiologically, where possible. RESULTS: In this low-dose imiglucerase treatment group: (i) there was a significant increase in Hb over time--normal Hb levels were achieved in 7 of the 9 patients after a mean of 3.7 years; (ii) platelet counts increased over time, reaching normal levels in 7 patients; (iii) there was a significant decrease in both ACE and TAP over time; (iv) heights and weights of the subjects increased significantly over time with treatment, normalising to the expected growth percentiles; and (v) organ size (liver and spleen) reduced with therapy in all patients measured. CONCLUSION: ERT with low-dose imiglucerase (+/- 10 U/kg/fortnight) ameliorates Gaucher disease-associated anaemia and thrombocytopenia. Low-dose ERT is effective and may be considered in resource-poor clinical situations when other alternatives are not available.

Adolescent↗
PubMed2003

CD44H and the isoforms CD44v5 and CD44v6 in the synovial fluid of the osteoarthritic human knee joint.

OBJECTIVE: To determine whether the concentrations of CD44H and v5 and v6 in the synovial fluid are correlated with the presence of accompanying synovitis in the osteoarthritic joint and with the grade of osteoarthritis. DESIGN: Using antero-posterior and lateral X-rays of the knee joint and patellar view of 46 patients were graded with the Kellgren & Lawrence scale. Synovial fluid from these patients with different grades of primary osteoarthritis of the knee joint with and without synovial inflammation (synovitis) was collected during surgical procedures. A horseradish peroxidase conjugated anti-CD44H-, anti-sCD44v5- or anti-sCD44v6-antibody was added and labeled with tetramethylbenzidine. The absorbance was measured at wavelengths of 450/620 nm. Regression analysis was performed and the statistical significance was assessed, using the Student t-test for unequal variance. RESULTS: CD44H and v5 and v6 were detected in the synovial fluid of all 46 patients. Osteoarthritic patients with synovial inflammation showed significantly higher levels of CD44H and v6, but not v5, than osteoarthritic patients without synovial inflammation. With progression of osteoarthritis from Kellgren grade II to III, CD44v5 decreased significantly. All other isoform concentrations remained statistically unchanged. CONCLUSIONS: CD44H and the isoforms v5 and v6 were present in the synovial fluid of osteoarthritic patients. Their concentrations do not reflect the osteoarthritic stage in the Kellgren grading scale. CD44H and CD44v6, but not CD44v5, are significantly up-regulated in osteoarthritic synovial inflammation.

Adult↗
PubMed2002

Genetic substructure in South African Bantu-speakers: evidence from autosomal DNA and Y-chromosome studies.

The extent of genetic differentiation between seven South African Bantu-speaking groups (Zulu, Xhosa, Tsonga/Shangaan, Southern Sotho, Pedi, Tswana, and Venda) was assessed from coancestry coefficients (F(ST)) estimated from autosomal serogenetic, DNA, and Y-chromosome DNA haplotypes. The overall F(ST) obtained from the autosomal data was 0.002, and that from the Y chromosome data was 0.014. The genetic relationships between groups examined were inferred from their cluster affinities in phylogenetic trees constructed from the genetic distances between them. Both autosomal and Y-chromosome DNA studies reveal that 6 of the 7 South African Bantu-speaking groups cluster according to their linguistic groupings, the exception being the Tsonga, who do not cluster with other Nguni language speakers, but rather with the Venda who live close to them. This suggests that the invading Shangaan-speakers, whose Nguni language was adopted by the Tsonga, did not have a major effect on the Tsonga gene pool, and that gene flow from the Venda into the Tsonga may have been considerable. Genetic distances were found to correlate with geographic distances between the regions where each group's apparent population density is the highest. Linguistic distances were also found to correlate with genetic distances, but linguistic and geographic distances showed no correlation. Together, these results suggest that linguistic and some genetic differentiation took place before the groups (or their forerunners) reached their present-day locations, and that further genetic change occurred after their arrival.

Adult↗
PubMed2001

Hippocampus and amygdala in schizophrenia: assessment of the relationship of neuroanatomy to psychopathology.

The hippocampus and amygdala are believed to be involved in the pathology of schizophrenia. In this study, we attempted to replicate the reported bilateral volume reduction of the hippocampus and amygdala and to study the relationship of the volumes of these structures to the symptoms of schizophrenia. The hippocampus-amygdala complex (HAC) was manually traced on 3-mm coronal T(1)-weighted MRIs, resampled into 1-mm coronal slices, from 20 male patients with schizophrenia and 20 age-matched male controls. The complex was divided into three parts: anterior one-third representing the amygdala and middle and posterior thirds representing the anterior and posterior halves of the hippocampus. Positive and negative symptoms and severity of hallucinations and thought disorder (conceptual disorganization) were quantified using the Brief Psychiatric Rating Scale (BPRS). None of the above structures, controlled for brain volume, differed significantly in patients compared with normal controls. When the relationship between volumes and symptoms was examined, the left HAC was found to inversely correlate with thought disorder and negative symptoms. Specifically, significant inverse correlations were found between (i) left amygdala and thought disorder, (ii) left hippocampus and negative symptoms, and (iii) left anterior and posterior hippocampus volumes and positive and negative symptoms, respectively. Our findings further support the role of the HAC in the pathophysiology of schizophrenia and suggest unique associations between individual structures and specific symptoms of the illness.

Adult↗
PubMed2001

Aberrant respiratory sensitivity to CO(2) as a trait of familial panic disorder.

BACKGROUND: According to three earlier studies, well individuals with a family history of panic disorder experience more anxiety following a single breath of 35% CO(2) than do those without such a family history. This study sought to determine whether a heightened sensitivity to CO(2) manifests specifically in respiratory changes. METHODS: Subjects were 18--35 years old and had no history of panic attacks and no current DSM-IV diagnosis other than simple or social phobia. Those at high risk for panic disorder (HR-P) (n = 46) had a first-degree relative with treated panic disorder. Low-risk control subjects (LR-C) (n = 39) had no first-degree relative with panic disorder. Respiratory measurements were taken continuously while subjects breathed room air through an attached mask for 3 min and, subsequently, while they breathed a 5% CO(2)/air mixture for an additional 3 min. RESULTS: HR-P subjects did not differ from control subjects by group means of the principal measure of respiratory response, changes in minute volume (MV) during CO(2) inhalation. However, these values assumed clearly different distributions in the two groups. Fifteen (32.6%) of the HR-P subjects showed a paradoxical decrease in MV while breathing CO(2) and six (13%) displayed a particularly rapid increase in MV. Only one (2.6%) of the control subjects had a negative MV slope and none had a high value [chi(2)(1) = 12.3, p <.001, p =.021, Fisher exact test, respectively]. Though the subjects with high MV increases also described greater increases in anxiety after breathing CO(2), a regression analysis indicated that the MV increase was the more important in discriminating high-risk from control subjects. CONCLUSIONS: These results suggest that respiratory sensitivity to CO(2) inhalation is operative in the familial transmission of panic disorder.

Adult↗
PubMed2001

Quinone-annonaceous acetogenins: synthesis and complex I inhibition studies of a new class of natural product hybrids.

The natural product hybrids quinone-mucocin and quinone- squamocin D were synthesized. In these hybrids, the butenolide unit of the annonaceous acetogenins mucocin and squamocin D is exchanged for the quinone moiety of the natural complex I substrate ubiquinone. For both syntheses, a modular, highly convergent approach was applied. Quinone-mucocin was constructed out of a tetrahydropyran (THP) component 1, a tetrahydrofuran (THF) unit 2, and a quinone precursor 3. A stereoselective, organometallic coupling reaction was chosen for the addition of the THP unit to the rest of the molecule. In the final step, the oxidation to the free quinone was achieved by using cerium(IV) ammonium nitrate (CAN) as the oxidizing agent. Quinone-squamocin D was assembled in a similar manner, from the chiral side chain bromide 16, the central bis-THF core 17, and the quinone precursor 18. Inhibition of complex I (isolated from bovine heart mitochondria) by the quinone acetogenins and several smaller building blocks was examined; quinone mucocin and quinone-squamocin D act as strong inhibitors of complex I. These results and the data from the smaller substructures indicate that other substructures of the acetogenins besides the butenolide group, such as the polyether component and the lipophilic left-hand side chain, are necessary for the strong binding of the acetogenins to complex I.

Animals↗
PubMed2001

Population-based association analyses of the HOPA12bp polymorphism for schizophrenia and hypothyroidism.

HOPA is an Xq13 chromosome gene that codes for a RXR nuclear receptor co-activator. In a prior study of the genetic basis of schizophrenia, we showed that exonic polymorphisms in HOPA were associated with increased risk of schizophrenia and hypothyroidism in a large cohort of probands from New York. In an attempt to replicate these findings, we examined this relationship in a cohort of 173 schizophrenic probands (128 males and 45 females providing 218 alleles) from Iowa. Consistent with the prior findings, we found an increased rate of the HOPA12bP exonic polymorphism in schizophrenic probands compared with random newborn controls (9 of 218 alleles vs. 33 of 2,049 alleles, P < 0.02). Furthermore, retrospective review of the medical records showed that two of the nine probands possessing the HOPA12bp allele in whom thyroid function was assessed were hypothyroid compared with 6 of 164 probands possessing the normal HOPAwild allele(s) (P < 0.06). We conclude that the HOPA12bp polymorphism shows a nominally significant association with schizophrenia and a nominal trend for association with hypothyroidism in our study and that further studies are required to define the features of this syndrome and the molecular mechanisms of disease pathogenesis.

Amino Acid Sequence↗
PubMed2001

Clozapine use in patients with schizophrenia and the risk of diabetes, hyperlipidemia, and hypertension: a claims-based approach.

BACKGROUND: Numerous case reports have linked clozapine to the development of diabetes mellitus and hyperlipidemia in patients with schizophrenia. However, investigators have been unable to clearly demonstrate this association when compared with a control group receiving conventional antipsychotics. METHODS: Medical and pharmacy claims from the Iowa Medicaid program were used to compare incidence rates for diabetes, hyperlipidemia, and hypertension in 552 patients receiving clozapine and 2461 patients receiving conventional antipsychotics (eg, haloperidol, chlorpromazine hydrochloride), with the use of a retrospective cohort design. Logistic regression was used to compare incidence rates adjusting for age, sex, and duration of available follow-up. RESULTS: No significant differences in overall incidence rates for diabetes, hyperlipidemia, or hypertension were observed in patients receiving clozapine vs conventional antipsychotics. However, among younger patients (aged 20-34 years), clozapine administration was associated with a significantly increased relative risk of diabetes (2.5 [95% confidence interval, 1.2-5.4]) and hyperlipidemia (2.4 [95% confidence interval, 1.1-5.2]), but not hypertension (0.9 [95% confidence interval, 0.4-2.0]). CONCLUSIONS: These data suggest that clozapine may not be an independent cause of diabetes or hyperlipidemia, but instead acts as an effect modifier in susceptible populations by increasing weight or affecting insulin secretion and resistance. This finding requires confirmation in other settings and patient populations and with the other atypical antipsychotics (risperidone, olanzapine, and quetiapine fumarate). The potential long-term medical and economic implications of the early induction of diabetes and hyperlipidemia in patients with schizophrenia warrant further study.

Adult↗
PubMed2001

Anatomic and functional variability: the effects of filter size in group fMRI data analysis.

In the analysis of group fMRI scans, an optimal spatial filter should be large enough to accurately blend functionally homologous anatomic regions, yet small enough not to blur the functionally distinct regions. Hanning filters varying from 0.0 to 18.0 mm were evaluated in a group analysis of six healthy controls performing a simple finger-tapping paradigm. Test-retest reliability and Talairach-based measurements of the sensorimotor region were used to explore the optimal filter size. Two distinct regions of functional activation were noted in the sensorimotor cortex in group images (n = 6) at both time 1 and time 2. These regions merge once the filter size exceeds approximately 6.0 mm. The original hypothesis that these represented a motor and sensory activation was rejected on the basis of structural and functional variability. A discussion of the inherent difficulties in choosing an appropriate filter size is presented.

Adult↗
PubMed2001

Cytogenetic-clinicopathologic correlations in rhabdomyosarcoma: a report of five cases.

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children younger than the age of 15 years. Histologically, RMS can be subdivided into two major subtypes; embryonal (E-RMS) and alveolar (A-RMS) rhabdomyosarcoma, with E-RMS being the more common. Although cytogenetic and molecular genetic findings have been reported extensively for RMS, clinicopathologic-genetic correlations among these tumors have not been reported in detail. In this report, we correlate the cytogenetic findings, including fluorescence in situ hybridization and spectral karyotyping, with pathologic findings and outcome for five RMS, including two A-RMS, one E-RMS, one botryoid RMS, and one anaplastic nonclassified RMS (N-RMS). The findings in A-RMS and E-RMS generally were consistent with previous reports; however, gain of chromosome 7 in A-RMS and gain of chromosome 9 segments in E-RMS observed here have seldom been reported in the literature. Importantly, the botryoid RMS had a cytogenetic profile similar to other types of E-RMS. An add(11)(q21) observed in this tumor, together with a t(8;11)(q12 approximately 13;q21) reported previously, indicates that 11q21 rearrangements may be nonrandomly related to botryoid RMS. In addition, the N-RMS expressed a cytogenetic pattern similar to that observed in E-RMS, thus providing genetic evidence that anaplastic N-RMS is a variant of E-RMS. Finally, these cases provide cogent evidence for the diagnostic and prognostic significance of the pathologic-genetic classification of RMS.

Adolescent↗
PubMed2001

Generating random series with known values of Kendall's tau.

Kendall's tau(a) offers statistical advantages to the more common Pearson's correlation and both are common in biomedical research. While generating random X-Y pairs from a known population value of Pearson's correlation is straightforward, the process for generating random sequences for a known value of Kendall's tau(a) is more complicated. Algorithms are presented that yield random numbers from a population with a known expected tau(a). They begin with a small set of values that have a known tau. These values are 'grown' to produce an arbitrarily large population that has the same expectation as the smaller set. Two examples are given. One example simulated samples from a population where tau(a) equaled 0.33 and confidence intervals are produced. A second example illustrates how the algorithm can be used to provide statistical power estimates for research studies using Kendall's tau(a).

Algorithms↗
PubMed2001

Unilateral vs. bilateral ultrasound in the monitoring of cerebral microemboli.

We used bilateral transcranial Doppler to monitor the number of microembolic events (ME) in the left and right middle cerebral arteries of 29 patients during cardiac surgery that required extracorporeal circulation. Based on a previously published study, we hypothesized that the commonly used method of doubling unilateral ME counts to obtain an estimated bihemispheric load would result in significant errors of estimation. In our sample, estimated bihemispheric counts were inaccurate by an average of 18% (range 0--80%). Despite this large range of error, calculation of Cronbach's alpha revealed that actual error due to unreliability (4%) was small relative to the large variation in ME counts across subjects in this patient series. These findings suggest that unilateral monitoring is sufficient when the goal is to characterize a given subject's ME load within the context of the other subjects in the sample. However, when precise ME counts are required, bilateral monitoring is essential.

Cardiac Surgical Procedures↗
PubMed2001

Effects of olanzapine on cerebellar functional connectivity in schizophrenia measured by fMRI during a simple motor task.

BACKGROUND: According to current theories, schizophrenia results from altered connectivity in brain circuits for fundamental cognitive operations. Consequently, the poorly understood mechanisms of neuroleptic treatment may be explainable by altered functional interactions within such networks. The 'cognitive dysmetria' model hypothesizes that one key structure in these circuits is the cerebellum. To investigate the effects of olanzapine on cerebellar functional connectivity (CFC), a seed-voxel correlation analysis (SVCA) was used in a functional magnetic resonance imaging (fMRI) study of a simple finger-tapping task. METHODS: fMRI scans were obtained from six schizophrenic patients under both drug-free and olanzapine-treated conditions and from a matched control group of six healthy subjects at corresponding time points. SVCAs were performed for anatomically and functionally standardized seed voxels in the anterior cerebellum. SVCA results were then processed by three different randomization analyses. RESULTS: The analyses revealed that olanzapine caused widespread changes of CFC, including prominent changes in prefrontal cortex and mediodorsal thalamus. Significant changes in motor structures were found after subtractions within both groups and may thus indicate repetition effects rather than drug effects. Olanzapine 'normalized' the patients' CFC patterns for the right, but not for the left cerebellum. CONCLUSION: Even for a simple motor task, olanzapine affects functional interactions between the cerebellum and many non-motor brain regions, including elements of the 'cognitive dysmetria' circuit. Altogether, our findings suggest that olanzapine has a stronger differential effect on neural activity in prefrontal cortex and thalamus than in motor structures.

Adult↗
PubMed2001

Caregiver report of hallucinations and paranoid delusions in elders aged 70 or older.

This study examined the demographic, medical, and psychiatric correlates of hallucinations and paranoid delusions reported by proxy informants for 822 elders aged 70 or older. This sample comprised people who were deemed unable to complete a direct interview in a large nationwide study of aging. Marital status, trouble with vision, and cognitive impairment were associated with report of both paranoid delusions and hallucinations. Depressive symptoms and stroke were associated with hallucinations only. These results suggest that inadequate external stimulation in the elderly leads to psychotic experiences.

Aged↗
PubMed2001

Bupropion SR vs. methylphenidate vs. placebo for attention deficit hyperactivity disorder in adults.

Despite the increasing recognition of attention-deficit hyperactivity disorder (ADHD) in adults, there are few controlled trials demonstrating the effectiveness of pharmacological treatments, particularly with nonstimulants. One controlled trial found bupropion SR more effective than placebo in the treatment of ADHD adults. We conducted a controlled study to contrast the effectiveness of bupropion SR and methylphenidate to placebo in ADHD adults. A randomized, double-blind, parallel design was used in this study. Following a 7-day placebo lead-in, 30 ADHD (DSM-IV) subjects (18-60 years old) were randomized to bupropion, methylphenidate, or placebo for 7 weeks. Methylphenidate was titrated over 1 week to a maximum dose of 0.9 mg/kg/d divided into 3 doses while bupropion was titrated over 2 weeks to a maximum dose of 200 mg A.M. and 100 mg P.M. Response rates based on Clinical Global Impression improvement ratings in patients receiving bupropion, methylphenidate, and placebo were 64, 50, and 27%, respectively. The difference in response rates between active treatment and placebo was not statistically significant (p = 0.14). Neuropsychological testing demonstrated trends favoring drug treatment on measures of immediate recall and verbal fluency. While bupropion SR may be a viable clinical alternative for adults with ADHD, further investigation is needed.

Adrenergic Agents↗