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Biomedical subjects

H J Hoffman

Publications and source records attributed to H J Hoffman.

At least 19 recordsLinked to original sources
PubMed2004

Valid across-group comparisons with labeled scales: the gLMS versus magnitude matching.

Labeled scales are commonly used for across-group comparisons. The labels consist of adjective/adverb intensity descriptors (e.g., "very strong"). The relative distances among descriptors are essentially constant but the absolute perceived intensities they denote vary with the domain to which they are applied (e.g., a "very strong" rose odor is weaker than a "very strong" headache), as if descriptors were printed on an elastic ruler that compresses or expands to fit the domain of interest. Variation in individual experience also causes the elastic ruler to compress or expand. Taste varies genetically: supertasters perceive the most intense tastes; nontasters, the weakest; and medium tasters, intermediate tastes. Taste intensity descriptors on conventional-labeled scales denote different absolute perceived intensities to the three groups making comparisons across the groups invalid. Magnitude matching provides valid comparisons by asking subjects to express tastes relative to a standard not related to taste (e.g., supertasters match tastes to louder sounds than do nontasters). Borrowing the logic of magnitude matching, we constructed a labeled scale using descriptors unrelated to taste. We reasoned that expressing tastes on a scale labeled in terms of all sensory experience might work. We generalized an existing scale, the Labeled Magnitude Scale (LMS), by placing the label "strongest imaginable sensation of any kind" at the top. One hundred subjects rated tastes and tones using the generalized LMS (gLMS) and magnitude matching. The two methods produced similar results suggesting that the gLMS is valid for taste comparisons across nontasters, medium tasters, and supertasters.

Adult↗
PubMed2001

Identification of the haemoglobin scavenger receptor.

Intravascular haemolysis is a physiological phenomenon as well as a severe pathological complication when accelerated in various autoimmune, infectious (such as malaria) and inherited (such as sickle cell disease) disorders. Haemoglobin released into plasma is captured by the acute phase protein haptoglobin, which is depleted from plasma during elevated haemolysis. Here we report the identification of the acute phase-regulated and signal-inducing macrophage protein, CD163, as a receptor that scavenges haemoglobin by mediating endocytosis of haptoglobin-haemoglobin complexes. CD163 binds only haptoglobin and haemoglobin in complex, which indicates the exposure of a receptor-binding neoepitope. The receptor-ligand interaction is Ca2+-dependent and of high affinity. Complexes of haemoglobin and multimeric haptoglobin (the 2-2 phenotype) exhibit higher functional affinity for CD 163 than do complexes of haemoglobin and dimeric haptoglobin (the 1-1 phenotype). Specific CD163-mediated endocytosis of haptoglobin-haemoglobin complexes is measurable in cells transfected with CD163 complementary DNA and in CD163-expressing myelo-monocytic lymphoma cells.

Animals↗
PubMed2001

Otoacoustic emissions and improved pass/fail separation using wavelet analysis and time windowing.

A new method is presented for the purpose of improving pass/fail separation during transient evoked otoacoustic emission (TEOAE) hearing screening. The method combines signal decomposition in scales using the discrete wavelet transform, non-linear denoising and scale-dependent time windowing. The cross-correlation coefficient between two subaveraged, processed TEOAE signals is used as a pass/fail criterion and assessed in relation to the pure-tone, mean hearing level. The performance is presented in terms of receiver operating characteristics for a database of 5,214 individuals. The results show that the specificity improves from 68% to 83% at a sensitivity of 90% when compared with the conventional wave reproducibility parameter.

Hearing Loss↗
PubMed2001

Genetic and environmental influences on self-reported reduced hearing in the old and oldest old.

OBJECTIVES: The aim of the present twin study was to estimate the relative importance of genetic and environmental factors in variation in self-reported reduced hearing among the old and the oldest old. DESIGN: Self-reported hearing abilities of older twins assessed at intake interview in a population-based longitudinal survey. SETTING: Denmark. PARTICIPANTS: Twins age 75 and older identified in the population-based Danish Twin Registry in 1995. An interview was conducted with 77% of 3,099 individuals in the study population. In 1997 and 1999, a follow-up contact to the survivors was made and an additional 2,778 twins, age 70-76, were included in the study. MEASUREMENTS: Reduced hearing was assessed by the same question in all interview waves. Heritability (proportion of the population variance attributable to genetic variation) was estimated using structural-equation analyses. RESULTS: The prevalence of self-reported reduced hearing corresponded to previous studies and showed the expected age and sex dependence. Concordance rates, odds ratios, and correlations were consistently higher for monozygotic twin pairs than for dizygotic twin pairs in all age and sex categories, indicating heritable effects. Structural-equation analyses revealed a substantial heritability for self-reported reduced hearing of 40% (95% CI = 19-53%). The remaining variation could be attributed to individuals' nonfamilial environments. CONCLUSION: We found that genetic factors play an important role in self-reported reduced hearing in both men and women age 70 and older. Because self-reports of reduced hearing involve misclassification, this estimate of the genetic influence on hearing disabilities is probably conservative. Hence, genetic and environmental factors play a substantial role in reduced hearing among the old and oldest old. This suggests that clinical epidemiological studies of age-related hearing loss should include not only information on environmental exposures but also on family history of hearing loss and, if possible, biological samples for future studies of candidate genes for hearing loss.

Aged↗
PubMed2001

Image-guided, frameless stereotactic sectioning of the corpus callosum in children with intractable epilepsy.

Corpus callosotomy is an effective neurosurgical procedure for children with intractable atonic or drop attack seizures. While this procedure has not changed significantly over the past three decades, some technical issues remain to be resolved. These include the intraoperative determination of the extent of the callosotomy, the need to stage the procedure, as well as side of approach of craniotomy. We report our 8-year experience with corpus callosotomy using a frameless stereotactic image-guided system (ISG Viewing Wand). Seventeen children with atonic seizures underwent sectioning of the corpus callosum. The mean patient age was 10.5 years. Six children underwent complete callosotomy while 11 underwent resection of the anterior two-thirds. MRI 3D reconstruction of the sagittal sinus and draining cerebral veins was undertaken in all cases. The side of the craniotomy was determined on the basis of favorability of the draining veins with respect to the extent of the callosotomy. The extent of the callosotomy was determined by intraoperative feedback using the ISG Viewing Wand((R)). Nine of 11 patients in the partial callosotomy group and 4 of 6 patients in the complete callosotomy group showed significant improvement in atonic seizures. We conclude that the use of frameless stereotaxy can function as an important adjunct in the planning and conduction of successful sectioning of the corpus callosum in children with intractable seizures.

Adolescent↗
PubMed2000

Factors associated with caregivers' choice of infant sleep position, 1994-1998: the National Infant Sleep Position Study.

CONTEXT: The success and simplicity of the 1994 national "Back to Sleep" campaign to reduce sudden infant death syndrome provides an opportunity to study which elements determine whether a behavior will change in the desired direction in response to a public health intervention. OBJECTIVE: To examine sociodemographic characteristics, motivation, and message exposure to ascertain which factors influenced a caregiver's choice of infant sleep position after implementation of the campaign. DESIGN: Annual nationally representative telephone surveys conducted between 1994 and 1998. SETTING: The 48 contiguous United States. PARTICIPANTS: Nighttime caregivers of infants born within the 7 months prior to interview between 1994 and 1998. Approximately 1000 interviews were conducted each year. MAIN OUTCOME MEASURES: The position the infant was usually placed in for sleep, sleep position recommendations received from specific sources, and reasons reported for position choice. RESULTS: Between 1994 and 1998, prone placement declined from 44% to 17% among white infants and from 53% to 32% among black infants. Supine placement increased from 27% to 58% among white infants and from 17% to 31% among black infants. During this period, reports of supine recommendations from at least 1 source doubled from 38% to 79%. From 1995 to 1998, 86% of caregivers who placed the infant prone reported receiving only nonprone recommendations. Infant comfort was given as a reason for prone placement by 82% of these caregivers. In multivariate analysis, physician recommendation of "supine not prone" had the strongest influence and was associated with decreased prone placement (odds ratio [OR], 0.25 [95% confidence interval [CI], 0.16-0.39]) and increased supine placement (OR, 3.37 [95% CI, 2.38-4.76]). Recommendations from all 4 sources (the physician, neonatal nurse, reading materials, and radio/television) further increased the probability of supine placement (OR, 6.01 [95% CI, 4.57-7.90]). Other factors independently associated with increased prone and decreased supine placement included maternal black race, parity of more than 1, and living in a southern or mid-Atlantic state. CONCLUSIONS: According to our study, as of 1998, approximately one fifth of infants were still placed prone, and only half were placed supine. Recommendations of supine placement during infancy by physicians at well-baby checks and by neonatal nursery staff and print and broadcast media have increased the proportion of infants placed supine. Caregiver beliefs regarding perceived advantages of prone sleeping should be addressed to attain further reduction in prone placement.

Choice Behavior↗
PubMed2000

Cognitive development of term small for gestational age children at five years of age.

AIM: To assess the relative significance for cognitive development of small for gestational age, parental demographic factors, and factors related to the child rearing environment. METHODS: IQ of a population based cohort of 338 term infants who were small for gestational age (SGA) and without major handicap, and a random control sample of 335 appropriate for gestational age (AGA) infants were compared at 5 years of age. RESULTS: The mean non-verbal IQ was four points lower, while the mean verbal IQ was three points lower for the children in the SGA group. The results were not confounded by parental demographic or child rearing factors. However, parental factors, including maternal non-verbal problem solving abilities, and child rearing style, accounted for 20% of the variance in non-verbal IQ, while SGA versus AGA status accounted for only 2%. The comparable numbers for verbal IQ were 30 and 1%. Furthermore, we found no evidence that the cognitive development of SGA children was more sensitive to a non-optimal child rearing environment than that of AGA children. Maternal smoking at conception was associated with a reduction in mean IQ comparable to that found for SGA status, and this effect was the same for SGA and AGA children. The cognitive function of asymmetric SGA was comparable to that of symmetric SGA children. CONCLUSIONS: Our findings indicate that child cognitive development is strongly associated with parental factors, but only marginally associated with intrauterine growth retardation.

Case-Control Studies↗
PubMed2000

Factors associated with tympanostomy tube insertion among preschool-aged children in the United States.

OBJECTIVES: Recurrent and persistent otitis media is often treated by tympanostomy tube insertion to ventilate the middle ear and restore hearing. This study examined the factors that predict which children are most likely to receive tympanostomy tubes through 3 years of age. METHODS: Multiple logistic regression was conducted on data from a nationally representative sample of children (N = 8285). RESULTS: By 3 years of age, 6.8% of US children had tubes inserted. Logistic regression indicated that after control for number of ear infections, children without any gaps in health insurance, who attended a day-care center, who were White, whose birth-weight was less than 1500 g, and who lived in the Midwest or South were significantly more likely to have tympanostomy tubes. CONCLUSIONS: These data suggest that differences exist as to who receives tubes. Of particular concern are differences by race/ethnicity and continuity of health insurance coverage. With expansions in health care coverage to larger proportions of uninsured children, it will be important to monitor these programs to ensure that all children who may need tympanostomy tubes have access to them.

Child, Preschool↗
PubMed1999

Interhemispheric interactions analyzed by coherence during flexor spasms.

OBJECTIVE: We used coherence analysis to test for leading discharges on an ipsilateral right mesial temporal lesion in a 5 year old boy with flexor spasms. METHOD: Digital EEG analysis with video-EEG telemetry was performed preparatory to epilepsy surgery. RESULTS: Study of 10 spasms with head drop and subsequent flexion of both arms demonstrated an interhemispheric time lag with secondary bilateral synchrony, with a mean difference of 17 ms. The right hemisphere led. After a lesionectomy with resection of epileptic regions (performed with electrocorticographical guidance), the patient has been seizure-free for 4 years. Pathology confirmed a low-grade mixed glioma and cortical dysgenesis. CONCLUSION: The coherence analysis demonstrated a pathway of secondary generalization, confirming that the lesional side was leading during ictal generalized discharges in flexor spasms.

Brain↗
PubMed1999

Frequent ear infections in association with child-care characteristics, based on the 1988 Child Health Supplement to the National Health Interview Survey.

Using the 1988 Child Health Supplement to the National Health Interview Survey, we analysed the association between child-care characteristics and frequent ear infections among children under 6 years attending child care. We observed strong associations for 1- to 2-year-old children for variables involving exposure to many different children, including number of children in the main setting and one or more changes in child-care arrangement in the past year. No significant effects were observed for the children under 1 year, but sample sizes were small. Likewise, no strong associations were observed for the 3- to 5-year-old children, but they may have outgrown the detrimental effects of repeated respiratory tract infections.

Child↗
PubMed1999

Laryngeal basement membrane thickening is not a reliable postmortem marker for SIDS: results from the Chicago Infant Mortality Study.

It has been suggested that laryngeal basement membrane (LBM) thickening is a pathognomonic postmortem marker for sudden infant death syndrome (SIDS) and is not seen in other causes of explained sudden infant death. To test this hypothesis, we evaluated longitudinal sections of the right hemilarynx taken through the midpoint of the true vocal cord from 129 SIDS cases and 77 postneonatal sudden infant death controls. Using a five-point semi-quantitative scale, maximum LBM thickness (LBMT) for SIDS cases and controls was not statistically different (mean, 2.39 + 0.69 and 2.40 + 0.77, respectively). Likewise, scores based on the average thickness along the entire basement membrane (i.e., "average" score), were not found to be different between SIDS cases and controls. Average and maximum LBMT increased with age in both SIDS cases and controls and were not different between SIDS cases and controls within each age interval. Similar trends in the distribution of maximum and average LBMTs were found between black and Hispanic SIDS and controls; the number of white/non-Hispanic infants was too low for meaningful comparisons. Maximum and average LBMTs were not different in SIDS cases and controls exposed to environmental tobacco compared with unexposed infants. The LBMTs also increased significantly with body weight and length in both SIDS cases and controls. Finally, there were no differences in LBMT in infants intubated prior to death compared with those who were not intubated. From these data, we conclude that LBMT is not pathognomonic of SIDS, is present or absent with equal frequency in SIDS and controls, increases with postnatal age, and does not correlate with passive smoke exposure. Therefore, LBMT should not be used to diagnose SIDS.

Basement Membrane↗
PubMed1999

Outcome of epilepsy surgery in the first three years of life.

PURPOSE: We analyzed our experience over a 6-year period with early-childhood patients who had undergone epilepsy surgery, and investigated the surgical outcomes. METHOD: We reviewed the medical records of 23 children, ages 0-3 years, who underwent epilepsy surgery between 1991 and 1996. RESULTS: Twenty children had partial seizures; two had infantile spasms; and one had generalized tonic-clonic seizures at onset. The mean age at onset of seizures was 4.7 months, and the mean age at time of surgery was 15.3 months. A total of 32 operations (21 focal cortical resections and 11 hemispherectomies) was performed. Five of 12 children with seizures secondary to a neuronal migration disorder had reoperations, including three who ultimately underwent complete hemispherectomy. The pathology consisted of hemimegalencephaly in three patients, focal cortical dysplasia (FCD) in eight, tuberous sclerosis in one, Sturge-Weber syndrome (SWS) in five, infarction in two, low-grade glioma (LGG) in three, and post-herpes simplex virus encephalitis (HSE) in one. The follow-up period ranged from 1 to 6.5 years (mean, 3.2 years) from patients' last operation. The seizure outcome according to Engel's criteria was class I in 12 patients, class II in three, class III in six and class IV in two. CONCLUSIONS: Seizure outcomes after surgery were less favorable in infants with FCD than in those with SWS and LGG. Seizure outcome for the patients with hemispherectomies was excellent, compared with those who had focal cortical resections.

Age Factors↗
PubMed1998

Age-related changes in the prevalence of smell/taste problems among the United States adult population. Results of the 1994 disability supplement to the National Health Interview Survey (NHIS).

Information about the prevalence of disorders of the chemical senses has been limited. In the late 1970s, the consensus among experts convened by the National Institutes of Health (NIH) was that more than 2 million adults in the United States had a disorder of smell or taste. A large, nonrandom survey conducted by the National Geographic Society in 1987 found that 1% of their 1.2 million respondents could not smell 3 or more of 6 odorants using a 'scratch and sniff' test. Age was an important factor, with a decline beginning in the second decade of life. No comparable data have been available for taste, although it has been suggested that the sense of taste remains more robust with age. The National Institute on Deafness and Other Communication Disorders (NIDCD), NIH, began collaborating with the National Center for Health Statistics (NCHS) in 1993 to acquire information on the prevalence of smell/taste problems using the Disability Supplement to the National Health Interview Survey (NHIS). This survey was administered to approximately 42,000 randomly-selected households (representing about 80,000 adults over 18 years of age) in 1994. Adjusted national estimates derived from this survey showed a prevalence of 2.7 million (1.4%) U.S. adults with an olfactory problem. Also, 1.1 million (0.6%) adults reported a gustatory problem. When smell or taste problems were combined, 3.2 million (1.65%) adults indicated a chronic chemosensory problem. The prevalence rates increased exponentially with age. Almost 40% with a chemosensory problem (1.5 million) were 65 years of age or greater. In a multivariate analysis, the individual's overall health status, other sensory impairments, functional limitations (including difficulty standing or bending), depression, phobia, and several other health-related characteristics were associated with an increase in the rate of chemosensory disorders.

Adolescent↗
PubMed1998

Comparison of the Green scale versus magnitude estimation for taste perception.

The Green scale is a new psychophysical method that is simple for subjects to use, but its relation with magnitude estimation has yet to be fully characterized. In comparing the consistency between the Green scale and magnitude estimation, we found that the former seems to provide a psychological oral sensation measurement that is different from the latter method. A simple correction formula can be derived.

Humans↗
PubMed1998

Utility of frameless stereotaxy in the resection of skull base and Basal cerebral lesions in children.

Since 1991, we have performed nearly 300 stereotactic procedures using the ISG viewing wand on a variety of cranial lesions in patients under 22 years of age. Of these, 38 procedures were performed on 34 patients for basal cerebral and skull base lesions. Our patients ranged in age from 3.5 months to 22 years with a mean age of 9.45 years. There were 18 females and 16 males. Twenty-one patients had basal cerebral lesions located in the thalamus (10), basal ganglia (2), third ventricle (2), and hypothalamus (7). Thirteen patients had skull base lesions located within the anterior optic apparatus (3), sella turcica (4), middle and posterior cranial fossae (4), and craniocervical region (2). Preoperative CT and/or MRI scan images were taken as a volume acquisition and transferred to the computer workstation utilizing the ISG Wand software. This workstation was transferred to the operating room where it was calibrated to a faro Surgicom arm which interfaces with the patient and the three-dimensional radiological image. The ISG Wand was utilized to plan the scalp and bone flaps and to select the optional trajectory to lesion. The surgical approaches which were specifically used in this series with the ISG Wand included transcallosal (15), pterional (5), frontal (3), subtemporal (4), transsphenoidal (3), temporal (3), tumor cyst shunt insertion (1), burr hole drainage (1), transoral (2), bifrontal (1), bifrontal mid facial (1), and transnasal (1). Although brain shift occurred following craniotomy and with brain retraction, the relative immobility of these lesions at the skull or cerebral base permitted an accurate targeting of all lesions with an error range of 1.0-2.5 mm throughout the entire procedure. This relatively precise intraoperative feedback led to more accurate recognition of tumor landmarks. It is the authors' impression that a more aggressive resection of these lesions was achieved than could be without the device. We conclude that a frameless stereotactic device such as the ISG Wand is particularly valuable in the approach to skull base and basal cerebral tumors in children.

Journal Article↗
PubMed1998

Surgical treatment of epilepsy in tuberous sclerosis: strategies and results in 18 patients.

BACKGROUND: Seizures in patients with tuberous sclerosis complex (TSC) are often intractable to antiepileptic medications and searching investigation may provide evidence that surgical treatment can be considered. OBJECTIVE: To review the results of investigation and surgical therapy, a treatment modality not generally considered in patients with medically refractory seizures and TSC. METHODS: We report 18 patients (9 male) with TSC who underwent surgical treatment of medically refractory epilepsy. Twelve patients had a well-localized epileptogenic lesion and were treated by lesionectomy or focal resection. Resections were: 7 frontal, 4 temporal, 1 frontotemporal, 1 occipital, and 1 frontoparietal. Four patients underwent more than one operation. Six patients had corpus callosotomy (CC). RESULTS: Follow-up ranged from 1 month to 47 years. Outcome of the patients treated by resection was excellent in 7 (5 were seizure-free and 2 had auras only), good in 1, fair in 3, and 1 was lost to follow-up. Best outcome was obtained in patients who had focal seizures and good imaging and EEG correlation, although they might have multiple seizure types, other imaging abnormalities, and multifocal or generalized EEG findings. When there was no such correlation, CC was found to be an option as five patients had at least some improvement and only one showed no change. CONCLUSION: Surgical treatment of patients with TSC and intractable epilepsy is most effective when a single tuber or epileptogenic area can be identified as the source of seizures and resected. This may be possible even when other tubers or diffuse EEG abnormalities are present. In patients with unlocalizable epileptic abnormalities, palliation may be obtained by CC.

Adolescent↗
PubMed1998

Neurodevelopmental outcome of small-for-gestational-age infants.

Despite many methodological difficulties, studies evaluating the relationship between being small for gestational age (SGA) at birth and various measures of adverse neurologic outcome generally show significant associations. Nevertheless, cerebral palsy is rarely found in SGA infants. Minimal neurologic dysfunction is more commonly seen in males and lower socioeconomic SGA children, and is often associated with attention deficits, hyperactivity, clumsiness, and poor school performance. Vision and hearing are generally not disturbed in SGA infants.

Attention Deficit Disorder with Hyperactivity↗