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Biomedical subjects

B L Hart

Publications and source records attributed to B L Hart.

At least 55 records · Page 3Linked to original sources
PubMed1995

Familial cerebral cavernous angiomas: clinical and radiologic studies.

Cavernous angiomas are well-circumscribed cerebrovascular malformations whose natural history is poorly understood. We reviewed 5,000 cranial MRI reports of studies performed between 1986 and 1993 and retrospectively evaluated the histories and imaging studies of 29 patients whose lesions were suggestive of cavernous angiomas. Patients ranged from 3 to 66 years and 27 were of Hispanic origin. The number of malformations per patient ranged from one to 30, and 24 patients had more than one lesion. In our series, the number of lesions per patient increased at a rate of one lesion per decade of age, but the mean size of the lesions was smaller with advancing decade (p < 0.05). All patients had MRI evidence of old or recent hemorrhage confined only to the malformation and adjacent brain. In only one patient was it deemed necessary to remove the malformation. Two excluded patients with typical lesions on MRI had small arteriovenous malformations found at surgery. Thus, MRI or CT cannot identify cavernous angiomas with certainty. This study supports studies that propose that cavernous angioma-like lesions, as identified by MRI or CT, are more common in Hispanics. It is possible that patients may not be born with MRI-identifiable malformations, but with advancing age the malformations become MRI-visible through malformation growth, hemorrhage, or both. The declining size by decade favors hemorrhage rather than growth. Cavernous angiomas may be more benign than previously thought.

Adolescent↗
PubMed1994

Effect of lordosis on the position of the nucleus pulposus in supine subjects. A study using magnetic resonance imaging.

STUDY DESIGN: Healthy young women (N = 20) underwent magnetic resonance imaging while supine with their hips and knees flexed (flexed position) and supine with a lumbar roll under the low back (extended position). The posterior and anterior margins of the nucleus pulposus (NP) relative to posterior and anterior margins of the adjacent vertebral bodies were calculated from mid-sagittal T2-weighted images to determine the position change of the NP as a function of two supine postures. OBJECTIVES: This study describes the effect of two commonly used supine postures on the position of the NP. SUMMARY OF BACKGROUND DATA: Management of patients with low back pain is often based on theorized positional changes of the NP during spinal extension and flexion. Data describing NP positional changes have not been reported for noninvasive measurements. RESULTS: The distance of the posterior margin of the NP to the posterior margins of the adjacent vertebral bodies was greater in the extended compared with the flexed position. There was no difference in the anterior distance. Eight of the 20 subjects had at least one degenerative disc in the lower lumbar spine. The NPs of the degenerative discs did not move the same as normal discs. CONCLUSIONS: The use of a lumbar roll under the low back when supine causes an increase in the distance from the posterior margin of the NP to the posterior portions of the vertebral bodies in normal discs of healthy young females. Degenerative discs deform differently from nondegenerative discs.

Adult↗
PubMed1994

Hypoplasia of the cerebellar vermis and cognitive deficits in survivors of childhood leukemia.

BACKGROUND: Neurodevelopmental evidence of the cerebellum's protracted course of postnatal development suggests that it is particularly sensitive to early toxic insult from cancer therapy. If this is the case, one would expect that there is a relationship between the pattern of neuropsychological and magnetic resonance imaging deficits and that both may indicate cerebellar abnormalities. OBJECTIVE: To investigate the profiles of neuropsychological functions and the morphologic features of the cerebellum, using in vivo magnetic resonance imaging planimetry in survivors of acute lymphoblastic leukemia (ALL) treated with radiation and chemotherapy. DESIGN: Thirteen survivors of childhood ALL with onset at age 2 to 5 years and a uniform protocol of treatment involving cranial radiation of 24 Gy and five doses of intrathecal methotrexate sodium participated in the study. Ten controls matched the patients in age and socioeconomic status. Each child was assessed with a comprehensive battery of neuropsychological tests and with magnetic resonance imaging of the brain. MEASUREMENTS: The neuropsychological scores were transformed into z scores and clustered into right and left hemisphere measures. Planimetric measures of the cerebellar vermis and pons were collected in the midsagittal plane. RESULTS: Consistently observed in survivors of ALL were the following: (1) significant cognitive deficits in visual-spatial-motor coordination and figural memory, functions commonly related to the right side of the brain; and (2) hypoplasia of the cerebellar vermis, lobuli I through V and particularly VI to VII. Lateralization of the neurobehavioral deficits was not reflected in structural brain abnormalities. CONCLUSIONS: Coexistence of the cerebellar hypoplasia and visual-motor coordination and memory deficits supports the neurodevelopmental approach to brain sequelae in survivors of ALL; it also suggests significance of the cerebellum for both motor and complex nonmotor cognitive processing.

Adolescent↗
PubMed1994

Behavioural defense against parasites: interaction with parasite invasiveness.

Behavioural patterns involved in avoiding, repelling, or removing parasites allow mammalian hosts to defend themselves from an array of parasites that threaten the host's fitness in the natural world. Some examples of behavioural defenses and the presumed target parasites are: grooming to remove ticks, grouping to reduce attack rate of biting flies, fly repelling movements to reduce parasitic flies, and selective grazing to reduce intake of faecal-borne parasites. These behavioural defenses are discussed with regard to effectiveness in controlling the target parasites. Parasites have sometimes evolved behavioural strategies of evading, penetrating or disabling these behavioural defenses. These parasite behavioural strategies, though less studied, are discussed. Also discussed is the possibility that host behavioural patterns that may defend against one parasite may be exploited by a different type of parasite to facilitate its own transmission. The interplay between host defensive strategies, the cost versus the effectiveness of such strategies, and a parasite's evasion or exploitation of such strategies, may be useful in understanding some aspects of host-parasite dynamics in nature.

Animals↗
PubMed1994

Metallic foreign bodies in the orbits of patients undergoing MR imaging: prevalence and value of radiography and CT before MR.

OBJECTIVE: The purpose of this study was to measure the prevalence of metallic foreign bodies in the orbits of 15,024 patients who were scheduled for MR imaging during a 4-year period and to determine if screening by plain radiography, CT, or both before MR imaging is efficacious. MATERIALS AND METHODS: Records of 15,024 patients scheduled for MR imaging were reviewed. A total of 1593 patients who had identified themselves as being at risk for an intraorbital metallic foreign body had undergone plain radiography or CT of the orbits. Plain radiographs and/or CT scans of patients reported as having orbital metal were reviewed to confirm the presence of a metallic foreign body and to identify its location. RESULTS: Metallic foreign bodies were discovered in 40 patients. Six of these patients had impaired vision in the involved eye. Ten patients had a metallic foreign body in or near the orbit but well away from the globe and were thought to be at low risk for movement of the foreign body as a result of MR imaging. The other 24 patients had metallic foreign bodies adjacent to or within the globe and were thought to be at risk for movement of the metallic foreign body as a result of MR imaging. CONCLUSION: The prevalence of intraorbital metallic foreign bodies in our study population was low (0.27%). Even in those patients identified as being at risk, the prevalence was only 2.5%. Based on the number of MR examinations performed annually in the United States and on data indicating that no radiographic screening is performed at 5% of institutions, we extrapolate that more than 2400 patients with intraorbital metallic foreign bodies have undergone MR imaging since 1986 without report of injury. These data allow us to infer that the risk of eye damage for patients who have intraorbital metal is low and that radiographic screening before MR imaging is not needed as often as it is done.

Blindness↗
PubMed1994

Fractures of the C-2 vertebral body.

Vertical C-2 body fractures are presented in 15 patients with clinical and imaging correlations that suggest the existence of a variety of mechanisms of injury. In these patients, clinical and imaging correlations were derived by: 1) defining the point of impact by clinical examination; 2) defining the point of impact by soft-tissue changes on cranial magnetic resonance (MR) imaging or computerized tomography (CT); 3) obtaining an accurate history of the mechanism of injury; and 4) spine imaging (x-ray studies, CT, and MR imaging) of the C-2 body fracture and surrounding bone and soft tissue. The cases presented involve the region located between the dens and the pars interarticularis of the axis. Although these fractures are rarely reported, they are not uncommon. An elucidation of their pathological anatomy helps to further the understanding of the mechanistic etiology of upper cervical spine trauma. A spectrum of mechanisms of injury causing upper cervical spine fractures was observed. The type of injury incurred is determined predominantly by the force vector applied during impact and the intrinsic strength and anatomy of C-2 and its surrounding spinal elements. From this clinical experience, two types of vertical C-2 body fractures are defined and presented: coronally oriented (Type 1) and sagittally oriented (Type 2). A third type of C-2 body fracture, the horizontal rostral C-2 fracture (Type 3), is added for completeness; this Type 3 fracture is the previously described Type III odontoid process fracture described by Anderson and D'Alonzo.

Adult↗
PubMed1994

Analysis of cerebral structural changes in systemic lupus erythematosus by proton MR spectroscopy.

PURPOSE: To determine whether cerebral atrophy in systemic lupus erythematosus is associated with decreased levels of the neuronal marker N-acetyl-aspartic acid. METHODS: Two groups of patients with systemic lupus erythematosus were studied, those with significant atrophy (n = 11) and those without significant atrophy (n = 10), using proton MR spectroscopy on a 1.5-T imaging unit. The solvent-suppressed, short-echo, volume-localized proton spectroscopy technique showed typical brain metabolites, including N-acetylaspartate, creatine/phosphocreatine, and choline-containing compounds. RESULTS: The N-acetylaspartate-to-creatine/phosphocreatine ratio was smaller in those patients with significant cerebral atrophy (1.68 +/- 0.27) than in those patients with minimal or no atrophy (2.17 +/- .30). The degree of atrophy was negatively correlated with the N-acetylaspartate-to-creatine/phosphocreatine ratio. The choline-to-creatine/phosphocreatine ratio was not significantly altered in systemic lupus erythematosus patients with atrophy. CONCLUSION: These data suggest that cerebral atrophy in systemic lupus erythematosus is associated with neuronal dropout (or damage), which results in decreased N-acetylaspartate ratios. A change in choline ratios is not implicated in the biochemical changes associated with cerebral atrophy. Proton MR spectroscopy may be useful in correlating brain metabolites with cerebral structural changes in patients with autoimmune diseases.

Adolescent↗
PubMed1993

Effectiveness of buspirone on urine spraying and inappropriate urination in cats.

The most frequent type of behavior problem in cats for which veterinary consultation is sought is problem urination. Urine spraying and urine marking have been treated by use of long-acting progestins and diazepam, a benzodiazepine antianxiety drug. Effectiveness of the nonbenzodiazepine antianxiety drug, buspirone, in suppressing urine spraying and marking in 47 male and 15 female cats was evaluated. The effect of the drug in correcting inappropriate urination in 9 cats also was evaluated. Buspirone resulted in a favorable response (> 75% reduction) in 55% of cats treated for urine spraying or marking. There was no sex difference in effectiveness of the treatment, but cats from single-cat households responded favorably significantly (P < 0.001) less frequently than those from multiple-cat households. The 55% response rate was within the range of treatment effectiveness that has been reported for diazepam, and was greater than that reported for progestin. In contrast to diazepam, with which over 90% of treated cats resumed spraying or marking when the drug was gradually discontinued, only half of the cats treated with buspirone resumed spraying when the drug was discontinued after 2 months of treatment (P < 0.001). This difference between diazepam and buspirone in resumption of urine spraying was attributed to diazepam's induction of physiologic and behavioral dependency, not found with buspirone. Cats that resumed spraying were placed on long-term treatment ranging from 6 to 18 months. Buspirone also did not cause the adverse effects of sedation and ataxia, which commonly are seen with diazepam treatment. In cats treated for inappropriate urination, 56% returned to normal litter box usage.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Neuromagnetic mapping of brain function.

Magnetic source imaging, a technique that combines magnetoencephalography (MEG) and magnetic resonance (MR) imaging, was used to localize the somatosensory and auditory cortex in seven healthy subjects. Functional neuromagnetic data were obtained with a 37-channel biomagnetometer. Structural MR imaging data were obtained with a 1.5-T superconducting imager. Coordinates used in defining MEG and MR imaging space were reconciled to produce magnetic source images that displayed the putative locations of somatosensory and auditory activity in relation to brain anatomy. Sources of somatosensory activity were typically localized to the postcentral gyrus; sources of auditory activity were localized to the superior temporal plane. Extension of these results to patients with tumors (or other disorders) that distort normal brain anatomy has the potential to make noninvasive magnetic source imaging examinations clinically useful in guiding neurosurgical interventional procedures.

Adult↗
PubMed1993

Use of radiology in U.S. general short-term hospitals: 1980-1990.

PURPOSE: To determine changes in usage of radiologic services between 1980 and 1990. MATERIALS AND METHODS: Complete data were obtained from 107 (42%) hospitals and incomplete data from eight (3%) (total survey response rate, 45%). Information was requested about the number of general radiologic examinations; specific modalities of computed tomography (CT), magnetic resonance (MR) imaging, nuclear medicine, and ultrasonography (US); and numbers of CT, MR imaging, and US machines. RESULTS: The number of general radiologic examinations in hospitals increased from approximately 126 million to 179 million (> 42%); for CT, from 3.6 million to 13.3 million; nuclear medicine, from 6.4 million to 7.4 million; and US, from 4.3 million to 11.8 million. MR imaging examinations performed during 1990 were estimated at 1.8 million. CONCLUSION: The number of radiologic examinations performed in U.S. hospitals increased by 30%-60% between 1980 and 1990, mainly due to increased usage of CT, MR imaging, and US.

American Hospital Association↗
PubMed1992

Comparison of diazepam with progestin for effectiveness in suppression of urine spraying behavior in cats.

The most common treatment for urine spraying and marking in cats has been administration of long-acting progestins. Treatment with diazepam has recently been gaining favor, particularly because of reported adverse effects of progestins. Results of a clinical trial involving 20 cats indicated that diazepam was effective in eliminating or markedly reducing spraying in 11 (55%) of them. However, most cats required continuous treatment, or at least intermittent treatment, when spraying recurred. The physiologic and behavioral dependency of cats on diazepam, which presumably develops over the course of administration, may contribute to the tendency for spraying to recur once diazepam treatment is discontinued. Using data from previously published findings on progestin administration, plus additional cases, it was documented that a significantly (P less than 0.05) higher percentage of males than females responded favorably. Although the number of cases was not sufficient for a statistical comparison of diazepam vs progestin treatment with regard to male vs female, possible gender difference in the effectiveness of diazepam was not indicated.

Animals↗
PubMed1992

Calcification of the trochlear apparatus of the orbit: CT appearance and association with diabetes and age.

OBJECTIVE: Calcification can sometimes be observed on CT scans in the region of the trochlear apparatus of the orbit, the cartilaginous structure through which the superior oblique tendon and its sheath pass. We evaluated associations of trochlear calcifications with age and diabetes. MATERIALS AND METHODS: We retrospectively reviewed CT scans of the orbit in 159 patients to identify the presence of trochlear calcifications. The presence or absence of diabetes, duration of diabetes, type of therapy, and presence or absence of neuropathy were determined from medical charts of 139 patients. We calculated the odds ratio of detecting a trochlear calcification and used logistic regression to evaluate the associations of age, sex, and diabetes with trochlear calcification. RESULTS: Trochlear calcifications were present in seven of the 24 diabetic patients and in 10 of the 115 nondiabetic patients. The odds ratio for detecting trochlear calcifications in diabetic vs nondiabetic patients was 4.3 (p < .01). Logistic regression showed univariate associations with trochlear calcification for both increasing age (p < .001) and diabetes mellitus (p < .01). The effect of diabetes on the prevalence of trochlear calcifications was seen predominantly in those less than 40 years old (odds ratio = 24.0, p = .014). Sex, duration of diabetes, insulin dependence, and neuropathy were not significantly associated with an increase in trochlear calcifications. CONCLUSION: The results show that a trochlear calcification seen on CT is a benign condition that may serve as a marker for diabetes in young patients. Trochlear calcifications are observed frequently (25-30%) in persons more than 50 years old. When it is present in patients younger than 40 years, it is strongly associated with diabetes.

Adolescent↗
PubMed1992

Behavioral adaptations to parasites: an ethological approach.

Wild vertebrate animals must live in an environment with the ever present threat of internal and external parasites. This threat by macroparasites is responsible for the natural selection of an array of behavioral adaptations that, together with the immune system and other physiological forms of resistance, enable the animals to survive and reproduce in this environment. Several lines of research, some quite recent, illustrate that specific behavioral patterns can be effective in helping animals or their offspring avoid or control macroparasites that can affect adversely the animal's fitness. These behavioral patterns fall under the general strategies of avoidance behavior and mate selection.

Animals↗
PubMed1991

The behavior of sick animals.

Dogs and cats that are ill with febrile diseases usually are depressed and anorexic. When viewed from the standpoint of the wild ancestors, it is apparent that the behavior of sick animals is adaptive and not necessarily a reflection of debilitation. A wild animal that is acutely ill with an infectious disease often is at a life-or-death juncture, and its behavioral mode may be seen as putting the animal's resources into facilitating the fever response in combating the pathogens.

Animals↗
PubMed1991

Cervical stenosis, spondylosis, and herniated disc disease.

While IntCECT is still considered by many to be the optimal modality in cervical spine imaging, it is the most invasive of the techniques considered here. MR imaging may have nearly equivalent diagnostic capability in many cases of degenerative disc and spine disease. The value of unenhanced CT essentially is limited to the demonstration of bony changes. In the evaluation of radiculopathy, either MR imaging or IvCECT is useful for the initial screening and may be the only study needed. MR imaging is the study of choice for diseases of the spinal cord. With continuing progress in MR capability, IntCECT is shifting more toward a supplemental or confirmatory role. A rigid neurodiagnostic algorithm for this common radiologic problem is not possible. Rather, each step of the diagnostic process is influenced by the individual patient. Specific patient characteristics may affect the selection of an imaging modality. Modification of routine studies, such as use of gadolinium or oblique MR imaging, may be indicated in some patients. Finally, because of the high prevalence of asymptomatic disc and spine changes, knowledge of clinical findings is essential in the accurate interpretation of anatomic findings.

Cervical Vertebrae↗