Biomedical subjects

Sharon Kim

Publications and source records attributed to Sharon Kim.

8 recordsLinked to original sources

PubMed2006

Stratification based on language-related endophenotypes in autism: attempt to replicate reported linkage.

The identification of autism susceptibility genes has been hampered by phenotypic heterogeneity of autism, among other factors. However, the use of endophenotypes has shown preliminary success in reducing heterogeneity and identifying potential autism-related susceptibility regions. To further explore the utility of using language-related endophenotypes, we performed linkage analysis on multiplex autism families stratified according to delayed expressive speech and also assessed the extent to which parental phenotype information would aid in identifying regions of linkage. A whole genome scan using a multipoint non-parametric linkage approach was performed in 133 families, stratifying the sample by phrase speech delay and word delay (WD). None of the regions reached suggested genome-wide or replication significance thresholds. However, several loci on chromosomes 1, 2, 4, 6, 7, 8, 9, 10, 12, 15, and 19 yielded nominally higher linkage signals in the delayed groups. The results did not support reported linkage findings for loci on chromosomes 7 or 13 that were a result of stratification based on the language delay endophenotype. In addition, inclusion of information on parental history of language delay did not appreciably affect the linkage results. The nominal increase in NPL scores across several regions using language delay endophenotypes for stratification suggests that this strategy may be useful in attenuating heterogeneity. However, the inconsistencies in regions identified across studies highlight the importance of increasing sample sizes to provide adequate power to test replications in independent samples.

Autistic Disorder↗

PubMed2005

The anatomy of temporal hollowing: the superficial temporal fat pad.

A coronal incision provides exposure to the lateral craniofacial skeleton for plastic surgeons, oral-maxillofacial surgeons, head and neck surgeons, neurosurgeons, and cosmetic surgeons. A common complication of this approach is hollowing of the temporal fossa. This hollowing results in a significant cosmetic deformity that affects the patient physically and psychologically. Current theories suggest that hollowing may result from atrophy of the superficial temporal fat pad caused by ischemia, displacement, or denervation of the fat pad. The purpose of this study is to identify the neurovascular supply and the supporting structures of the superficial temporal fat pad. Eight fresh-frozen cadaver heads were injected with latex to facilitate identification of vessels. Through coronal incisions, the anatomy of the vessels, nerves, and fascial network within the superficial temporal fat pads were recorded. The vascular supply of the superficial temporal fat pad includes branching perforators from the deep and middle temporal arteries that traverse through the substance of the fat pad. The branches of the zygomaticotemporal nerve travel through the superficial temporal fat pad. There is a network of septations that suspends the superficial temporal fat pad to the anterior fascia. This is the first step to understanding the etiology of postoperative temporal hollowing. This study provides the basis for a prospective randomized clinical trial investigating temporal hollowing after different surgical exposures of the area.

Adipose Tissue↗

PubMed2005

The anatomy of temporal hollowing: the superficial temporal fat pad.

A coronal incision provides exposure to the lateral craniofacial skeleton for plastic surgeons, oral-maxillofacial surgeons, head and neck surgeons, neurosurgeons, and cosmetic surgeons. A common complication of this approach is hollowing of the temporal fossa. This hollowing results in a significant cosmetic deformity that affects the patient physically and psychologically. Current theories suggest that hollowing may result from atrophy of the superficial temporal fat pad resulting from ischemia, displacement, or denervation of the fat pad. The purpose of this study is to identify the neurovascular supply and the supporting structures of the superficial temporal fat pad. Eight fresh-frozen cadaver heads were injected with latex to facilitate identification of vessels. Through coronal incisions, the anatomy of the vessels, nerves, and fascial network within the superficial temporal fat pads were recorded. The vascular supply of the superficial temporal fat pad includes branching perforators from the deep and middle temporal arteries that traverse through the substance of the fat pad. The branches of the zygomaticotemporal nerve travel through the superficial temporal fat pad. There is a network of septations that suspends the superficial temporal fat pad to the anterior fascia. This is the first step to understanding the etiology of postoperative temporal hollowing. This study provides the basis for a prospective, randomized clinical trial investigating temporal hollowing after different surgical exposures of the area.

Adipose Tissue↗

PubMed2004

Abnormal gyral complexity in first-episode schizophrenia.

BACKGROUND: Abnormalities in the patterns and frequency of cortical folding might help identify temporal and regionally specific disturbances in normal neurodevelopmental processes that occur in association with schizophrenia. Few studies, however, have investigated gyral complexity in schizophrenia. METHODS: High-resolution magnetic resonance images were used to examine differences in gyral complexity, measured three-dimensionally in five separate hemispheric regions covering the entire cortical surface, in patients with first-episode schizophrenia (n = 50) compared with demographically matched healthy comparison subjects (n = 50). The modulating effects of gender and hemisphere were also examined. RESULTS: Significant increases in cortical folding were observed in the right superior frontal cortex in male schizophrenic patients compared with male control subjects, but not between female diagnostic groups. Significant main effects of hemisphere were found in frontal, parietal, and occipital regions in directions complementary to cerebral torques. CONCLUSIONS: Results support previous findings of right frontal hypergyria in male schizophrenic patients and suggest that these abnormalities predate illness onset and are of neurodevelopmental origin. Therefore, in schizophrenia, sexually dimorphic developmental processes and differences in hemispheric connectivity, which have been shown to influence the organization and/or frequency of cortical folding, seem to be disturbed during gyral formation in utero.

Adult↗

PubMed2004

Regional specificity of hippocampal volume reductions in first-episode schizophrenia.

Hippocampal volume reductions are widely observed in schizophrenia. Some studies suggest anterior hippocampal regions are more susceptible and associated with frontal lobe dysfunctions, while others implicate posterior regions. Using high-resolution MR images and novel computational image analysis methods, we identified the hippocampal subregions most vulnerable to disease processes in 62 (45 m/17 f) first-episode schizophrenia patients compared to 60 (30 m/30 f) healthy controls, similar in age. The hippocampi were traced on coronal brain slices and hemispheric volumes were compared between diagnostic groups. Regional structural abnormalities were identified by comparing distances, measured from homologous hippocampal surface points to the central core of each individual's hippocampal surface model, between groups in 3D. CSF concentrations were also compared statistically at homologous hippocampal surface points to localize corresponding gray matter reductions. Significant bilateral hippocampal volume reductions were observed in schizophrenia irrespective of brain size corrections. Statistical mapping results, confirmed by permutation testing, showed pronounced left hemisphere shape differences in anterior and midbody CA1 and CA2 regions in patients. Significant CSF increases surrounding the hippocampus were observed in a similar spatial pattern in schizophrenia. Results confirm that hippocampal volume reductions are a robust neuroanatomical correlate of schizophrenia and are present by first episode. Mid- to antero-lateral hippocampal regions show pronounced volume changes and complementary increases in peri-hippocampal CSF, suggesting that these hippocampal regions are more susceptible to disease processes in schizophrenia. Targeting regional hippocampal abnormalities may help dissociate schizophrenia patients from other groups exhibiting global hippocampal volume changes, and better focus systems-level pathophysiological hypotheses.

Adolescent↗

PubMed2003

Increases in regional subarachnoid CSF without apparent cortical gray matter deficits in schizophrenia: modulating effects of sex and age.

OBJECTIVE: The authors investigated the modulating effects of biological sex and age on regional decreases in cortical gray matter and increases in subarachnoid CSF in 25 patients with chronic schizophrenia and 28 group-matched healthy comparison subjects. METHOD: Computational cortical pattern-matching methods were employed to measure the local proportions of gray matter and subarachnoid CSF at thousands of homologous cortical surface locations in each subject using high-resolution magnetic resonance images. Principal-component analysis reduced tissue proportion values obtained at each cortical surface point into component scores for each subject. Principal-component analysis scores were used as dependent variables in statistical analyses that included diagnosis, age, and sex as predictor variables. To reveal more regional changes in tissue proportions, statistical differences in gray matter and CSF were compared at each cortical surface location and mapped in three dimensions. RESULTS: Principal-component analyses revealed main effects of diagnosis, sex, and age for the CSF increases seen in the schizophrenia patients, in male subjects, and in association with age. Significant diagnosis-by-age, diagnosis-by-sex, and diagnosis-by-sex-by-age interactions were also observed, revealing CSF increases in male patients at younger ages. Statistical maps showed regional increases in subarachnoid CSF in association with the above effects. For cortical gray matter measurements, only main effects of age were observed. CONCLUSIONS: Regionally specific increases in sulcal and subarachnoid CSF occur during adulthood and appear prematurely in male schizophrenia patients. Cortical gray matter reductions show aging effects but are below the threshold of significance in schizophrenia.

Adult↗

PubMed2002

Genetic contributions to altered callosal morphology in schizophrenia.

Patients with schizophrenia exhibit abnormalities in midsagittal corpus callosum area, shape, and/or displacement. Our goal was to confirm these findings and to establish the genetic and nongenetic contributions to altered callosal morphology in schizophrenia. Relationships between ventricular enlargements potentially contributing to callosal displacements were assessed as a secondary goal. High-resolution magnetic resonance images were obtained from co-twins of monozygotic and dizygotic pairs discordant for schizophrenia and healthy control twins (N = 40 pairs). Investigators blind to group status segmented the corpus callosum and ventricles in native brain volumes aligned using a rigid-body transformation with no scaling. Total and parcellated midsagittal callosal areas and measures indexing vertical displacements of the corpus callosum were used in statistical tests to identify schizophrenia and sex effects and to dissociate genetic and nongenetic influences on morphology. Anatomical mesh modeling methods provided group average and surface variability maps of the callosum. Callosal areas did not differ between groups defined by sex or biological risk. Vertical displacements of the callosum, pronounced in male patients, were confirmed in schizophrenia and observed between dizygotic, but not monozygotic co-twins discordant for schizophrenia. Like their affected twins, however, unaffected monozygotic co-twins of the schizophrenia probands exhibited significant callosal displacements. Lateral and third ventricle enlargements were related to callosal displacements. Results clearly support that genetic rather than disease-specific or shared environmental influences contribute to altered callosal morphology in schizophrenia. An upward bowing of the callosum may thus provide an easily identifiable neuroanatomic marker to screen individuals possessing a biological vulnerability for schizophrenia.

Brain Mapping↗

PubMedDate not supplied

Weight uniformity of split tablets required by a Veterans Affairs policy.

OBJECTIVE: To split several tablet products relevant to the Veterans Affairs (VA) Maryland Healthcare System and assess whether the resulting half tablets provide equal doses. METHODS: From a VA list of products that are required to be split, 7 products were evaluated, along with 5 other commonly split tablet products. A trained pharmacy student split tablets using a tablet splitter provided by the VA. Half tablets were assessed for weight uniformity. RESULTS: Of the 12 products subjected to splitting, 8 products (atorvastatin, citalopram, furosemide, glipizide, metoprolol, paroxetine, sertraline, and warfarin) yielded half tablets that passed the weight-uniformity test. The 4 failing products were lisinopril, lovastatin, rofecoxib, and simvastatin. Unusual tablet shape and high tablet hardness predisposed products to failing the weight-uniformity test. The 4 failing products resulted in half tablets that were generally within 20% of their target weight range, suggesting that splitting these specific products would not result in adverse therapeutic effects due to dose variation created by tablet-splitting. CONCLUSION: Split-tablet results were relatively favorable and generally support a VA practice to split specific tablets. Public quality standards for half tablets, including their content uniformity, are needed to better delineate the policies for acceptable tablet splitting.

Dose-Response Relationship, Drug↗