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Biomedical subjects

H J Landy

Publications and source records attributed to H J Landy.

At least 19 recordsLinked to original sources
PubMed1996

Arteriovenous malformation associated with pleomorphic xanthoastrocytoma.

A case of a left temporo-occipital arteriovenous malformation associated with a pleomorphic xanthoastrocytoma is described. The patient had the vascular lesion with a stable right hemiparesis for many years prior to his recent clinical deterioration. Correlation is made with nine previously reported cases of angiogliomas. With the close proximity and temporal correlation of the two components of this lesion, as well as pathological evidence, the authors propose that angioglioma may be the product of reactive glial proliferation and transformation secondary to a pre-existing vascular malformation and hemorrhage.

Astrocytes↗
PubMed1996

Diagnosing gestational diabetes mellitus: use of a glucose screen without administering the glucose tolerance test.

OBJECTIVE: To determine if a 1-hour glucose screen value could be identified, above which gestational diabetes mellitus could be diagnosed without the 3-hour oral glucose tolerance test (GTT). METHODS: Demographic, historic, obstetric, and neonatal data from 514 singleton pregnancies with glucose screen values at least 140 mg/dL followed by a GTT were reviewed (312 patients with normal GTTs and 202 with gestational diabetes mellitus). Statistical analyses used chi2, Fisher exact, Student t, and Mann-Whitney tests. After determining the optimal glucose screen cutoff point using receiver operating characteristic curve analyses, patients were regrouped according to this value and analyzed further. RESULTS: The optimal cutoff point for the upper limit of the glucose screen was determined to be 186 mg/dL (95.9% specificity, 98.2% negative predictive value, 36.1% sensitivity, and 19.6% positive predictive value). Comparison of patients with elevated screens and normal GTTs versus those with gestational diabetes revealed significant differences only regarding a history of gestational diabetes mellitus and neonatal hypoglycemia in the studied pregnancy. Those with screens greater than 185 mg/dL behaved like diabetic patients and, when compared with subjects with screens of 140-185 mg/dL, also had a significantly greater proportion of large for gestational age infants. CONCLUSION: Patients with 1-hour glucose screens greater than 185 mg/dL have a high probability of gestational diabetes mellitus and the diagnosis can be made without the GTT. Using this approach could allow prompt initiation of therapy without the inconvenience and discomfort of the GTT.

Adolescent↗
PubMed1996

The fetus with gastroschisis: impact of route of delivery and prenatal ultrasonography.

OBJECTIVES: Our purpose was (1) to assess the influence of delivery route on neonatal outcome in fetuses with gastroschisis and (2) to correlate ultrasonographic appearance of fetal bowel with immediate postnatal outcome. STUDY DESIGN: Forty-seven cases (1986 to 1994) were reviewed; three abortions and two stillbirths were excluded. Ultrasonographic appearance of fetal bowel (small bowel dilatation > 10 mm) was evaluated in 27 cases. RESULTS: Twenty-six infants (61.9%) were delivered vaginally and 16 (38.1%) by cesarean section (11 elective, 5 in labor). Delivery route was not significantly associated with indicators of neonatal outcome (rate of primary closure, postoperative complications, days of parenteral nutrition, days to oral feeding, hospital days, or mortality). When ultrasonographic appearance of fetal bowel was correlated with outcome, fetuses with prenatally dilated bowel had significantly more bowel edema at birth (p=0.038), longer operative time (p=0.013), and higher overall rate of postoperative complications (p=0.037). CONCLUSIONS: (1) Elective cesarean delivery does not improve neonatal outcome in infants with gastroschisis. (2) Abnormal ultrasonographic appearance of fetal bowel is associated with a more difficult repair and a higher overall incidence of postoperative complications.

Abdominal Muscles↗
PubMed1996

Retrospective epidemiologic analysis of patients diagnosed with intracranial meningioma from 1977 to 1990 at the Jackson Memorial Hospital, Sylvester Comprehensive Cancer Center: the Jackson Memorial Hospital Tumor Registry experience.

A descriptive analysis was performed of the Tumor Registry data for intracranial meningioma by the Jackson Memorial Hospital, University of Miami School of Medicine Tumor Registry. A total of 108 cases of intracranial meningioma was collected and reviewed. Overall survival for 2, 5, and 10 years was 82, 72, and 60%, respectively. There was no difference in survival for males and females at 5 years, nor any difference in survival for race or ethnicity. There was a trend for improved survival for the young age group (18-55 years).

Adult↗
PubMed1994

Long-term follow-up of gliomas treated with fractionated stereotactic irradiation.

Eighteen patients have been treated for gliomas with fractionated stereotactic linear accelerator (LINAC) irradiation. A plastic halo ring secured with skull pins allows daily attachment of the patient to the stereotactic frame mounted on the linear accelerator. The patients received 9-31 fractions of 1.8-3 Gy/fraction over periods of 20-49 days. Total doses delivered stereotactically where 16-60 Gy (90% isodose) delivered to 3-7 cm diameter tumors. The six patients with glioblastoma had a median survival of 16 months (range 7-60 months). The two patients with anaplastic astrocytoma survived 7 and 78 months. Most of the patients with high grade tumors also received other adjuant treatments. Of the ten patients with low grade gliomas, one expired 66 months after treatment, and the remainder are alive 22-82 months after treatment. One pediatric patient displayed evidence of focal radiation injury with visual loss. No patient developed initial recurrence of tumor outside the focally irradiated field. Stereotactic localization of irradiation protects surrounding brain tissue; fractionation improves the therapeutic ratio. These extended follow-up data indicate that stereotactic restriction of radiation fields in treatment of gliomas does not result in deterioration of survival results. Further investigation is warranted into the use of higher focal fractionated radiation doses to attempt to improve local control and survival.

Adolescent↗
PubMed1994

Drug resistance in brain tumors.

Resistance to chemotherapy in brain tumors is complex and may involve multiple mechanisms. For commonly used drugs, such as nitrosoureas and platinum compounds, major mechanisms may involve increaded DNA repair or removal of the drug-DNA adducts. For water soluble nitrosoureas and also for platinum compounds, other mechanisms, such as alteration in drug transport, may be important. Another major mechanism may involve glutathione and glutathione-S-transferase pathways. For vinca alkaloids and epipodophyllotoxins p-glycoprotein mediated MDR appears to be the major feature in drug resistance. In addition, alteration of tubulin and topoisomerase II have been described in resistance to vinca alkaloids and epipodophyllotoxins respectively. Recently, increased multidrug resistance associated protein gene expression has been found in glioma cells and brain tumor samples; its clinical significance requires further investigation.

Animals↗
PubMed1994

Retreatment of intracranial gliomas.

Although intracranial gliomas carry a poor long-term prognosis, retreatment at the time of tumor progression may prolong survival and maintain or improve the quality of life. Thirty-three patients who underwent retreatment with surgery, radiotherapy, and chemotherapy were reviewed retrospectively. Median survival after initiation of retreatment was 8 months for glioblastoma, 13 months for anaplastic astrocytoma, 22 months for astrocytoma, and 47 months for oligodendroglioma/mixed glioma. Survival was significantly better for younger patients and for those with better functional status. One third of patients were neurologically improved by surgery. Surgical morbidity was minimal (2.1%); there was no surgical mortality. Chemotherapy and radiotherapy produced expected adverse reactions. Retreatment of intracranial gliomas carries acceptable risk and is beneficial in selected patients. Decisions regarding retreatment must be carefully individualized with consideration of the quality of life and the wishes of the patient and family.

Adult↗
PubMed1993

Comprehensive evaluation of left hemisphere type I schizencephaly.

We report the neuropsychological, magnetic resonance imaging, electroencephalographic telemetry, and sodium amytal test findings of a 32-year-old, left-handed man with unilateral left hemisphere type I schizencephaly. The patient was referred for treatment of medically refractory left temporal complex partial seizures that developed at age 26 years. Sodium amytal testing revealed complete incorporation of speech and language function by the right hemisphere. Detailed neuropsychological evaluation indicated average to above-average performance on all measures of language skills, judgment and reasoning, visuospatial abilities, and memory function. This case demonstrates that extensive but lateralized neuronal migration disorders can be associated with complete reorganization and full recovery of function by the contralateral hemisphere. Furthermore, this case supports the view that the degree of recovery is greatest when compensatory mechanisms are activated antenatally.

Adult↗
PubMed1993

Effects of vagal nerve stimulation on laryngeal function.

Functional electrical stimulation is a developing methodology that shows significant potential in the management of peripheral neuromuscular deficits. Potential applications in the head and neck area, including control of bilateral vocal fold paralysis and spasmodic dysphonia, have recently been explored. Despite promising early results, very little is known about the mechanisms of action or the long-term effects of electrical stimulation on human laryngeal function. Recent development of implantable vagal nerve stimulators as a method to control intractable seizures in individuals who have not responded to medication provides a unique opportunity to study its effect on the normal human larynx. Laryngeal and vocal function testing was studied on five individuals who had undergone vagal nerve stimulator implants for intractable seizures. Consistent abduction/adduction of the left vocal fold was achieved at 20 and 40 Hz, respectively. Higher levels of electrical stimulation produced hemispasm of the larynx. Results were consistent with studies in the literature of recurrent laryngeal nerve stimulation in animal and human models. The vagus nerve provides relatively easy access for implantation of electrodes to provide electrical stimulation to the muscles of the larynx. Vagal nerve stimulation may prove efficacious in the treatment of movement disorders of the larynx; further study is needed.

Adult↗
PubMed1993

Vagus nerve stimulation for complex partial seizures: surgical technique, safety, and efficacy.

Electrical stimulation of the vagus nerve has shown efficacy in controlling seizures in experimental models, and early clinical trials have suggested possible benefit in humans. Eleven patients with complex partial seizures were subjected to implantation of vagus nerve stimulators. Electrode contacts embedded in silicone rubber spirals were placed on the left vagus nerve in the low cervical area. A transcutaneously programmable stimulator module was placed in an infraclavicular subcutaneous pocket and connected to the electrode. One patient required replacement of the system due to electrode fracture. Another patient developed delayed ipsilateral vocal-cord paralysis; the technique was then modified to allow more tolerance for postoperative nerve edema. A third patient showed asymptomatic vocal-cord paresis on immediate postoperative laryngoscopy. Vagus nerve stimulation produces transient vocal-cord dysfunction while the current is on. Nine patients were randomly assigned to receive either high- or low-current stimulation, and seizure frequency was recorded. The high-current stimulation group showed a median reduction in seizure frequency of 27.7% compared to the preimplantation baseline, while the low-current stimulation group showed a median increase of 6.3%. This difference approached statistical significance. The entire population then received maximally tolerable stimulation. The high-current stimulation group showed a further 14.3% reduction, while the low-current stimulation group showed a 25.4% reduction compared to the blinded period. The efficacy of vagus nerve stimulation seemed to depend on stimulus parameters, and a cumulative effect was evident. These results are encouraging, and further study of this modality as an adjunct treatment for epilepsy is warranted.

Adult↗
PubMed1993

A non-hemorrhagic manifestation of vasa previa: a clinicopathologic case report.

BACKGROUND: The rare entity of vasa previa occurs when fetal vessels lying between the amniotic and chorionic membranes cross the cervical os. This report presents a case that was associated with vessel compression and concomitant adverse effects on fetal hemodynamics. CASE: A 23-year-old nulliparous woman at 36 weeks' gestation developed persistent, progressive severe variable decelerations several hours after spontaneous rupture of the membranes, resulting in a decision to perform a cesarean. At delivery, fetal vessels were noted in the membranes near the cervical os, leading into a marginally inserted cord. The decelerations were attributed to compression of the unprotected umbilical arteries by the fetal head. CONCLUSION: Vasa previa often results in fetal death and may be associated with fetal hemorrhage, but lack of bleeding does not exclude the existence of vasa previa. Altered fetal hemodynamics from varying degrees of vessel compression by the presenting part during labor may result in hypoxia and acidosis. A high index of suspicion is necessary to make the diagnosis and institute proper, timely management.

Adult↗
PubMed1992

Temporal lobectomy for seizures associated with unilateral schizencephaly.

Schizencephaly is characterized by unilateral or bilateral cerebral clefts associated with neurologic deficits and epilepsy. Most commonly schizencephaly is attributed to abnormal neuronal migration, and these malformations are well visualized by current neuroimaging techniques. This report describes a patient with unilateral schizencephaly and poorly controlled complex partial seizures who was found to have a temporal lobe seizure focus; anterior temporal lobectomy produced nearly complete control of the seizures. Despite the extensive malformation, relatively restricted resection was of significant benefit. The principles of seizure focus localization and resection are applicable to the management of patients with schizencephaly.

Adult↗
PubMed1992

Computer controlled stereotaxic radiotherapy system.

A computer-controlled stereotaxic radiotherapy system based on a low-frequency magnetic field technology integrated with a single fixation point stereotaxic guide has been designed and instituted. The magnetic field, generated in space by a special field source located in the accelerator gantry, is digitized in real time by a field sensor that is six degree-of-freedom measurement device. As this sensor is an integral part of the patient stereotaxic halo, the patient position (x, y, z) and orientation (azimuth, elevation, roll) within the accelerator frame of reference are always known. Six parameters--three coordinates and three Euler space angles--are continuously transmitted to a computer where they are analyzed and compared with the stereotaxic parameters of the target point. Hence, the system facilitates rapid and accurate patient set-up for stereotaxic treatment as well as monitoring of patient during the subsequent irradiation session. The stereotaxic system has been developed to promote the integration of diagnostic and therapeutic procedures, with the specific aim of integrating CT and/or MR aided tumor localization and long term (4- to 7-week) fractionated radiotherapy of small intracranial and ocular lesions.

Electromagnetic Phenomena↗
PubMed1992

Obstetric performance in patients with the lupus anticoagulant and/or anticardiolipin antibodies.

Antiphospholipid antibodies, notably the lupus anticoagulant and anticardiolipin antibodies, are associated with recurrent fetal wastage, pregnancy complications, and thromboses. Aggressive medical treatment using aspirin and steroids has been recommended. Fifty-one patients with antiphospholipid antibodies, only four with underlying connective tissue disorders, were followed through 53 pregnancies. Aggressive therapy was used in 33 pregnancies, 90.9% of which resulted in successful obstetric outcomes, a highly statistically significant difference compared with previous pregnancies in the same patients. Most pregnancies among nine patients receiving single-agent therapy (aspirin or steroids alone) and eight patients not treated also had successful outcomes. A 48.6% complication rate was found in association with therapy, particularly gestational diabetes mellitus. There was no statistical correlation between dose or duration of therapy and development of treatment-related complications. Although a subgroup of patients with antiphospholipid antibodies will benefit from aggressive therapy, the high complication rate warrants close observation.

Adrenal Cortex Hormones↗
PubMed1991

Intraoperative ultrasonography and cortical mapping for removal of deep cerebral tumors.

Stereotactic biopsies of brain tumors have recently become frequent, but prognosis may be improved by more aggressive surgery for primary and metastatic tumors. This report describes techniques for debulking and removal of deep cerebral tumors that are commonly subjected only to biopsy. With the use of intraoperative cranial ultrasonography and cortical mapping, five gliomas were debulked and three metastatic lesions were grossly totally removed. No complications occurred, and the patients with metastatic disease had striking neurologic improvement. Deep cerebral tumors may be treated aggressively with appropriate surgical techniques in selected patients.

Adolescent↗
PubMed1990

Small-field stereotactic external-beam radiation therapy of intracranial lesions: fractionated treatment with a fixed-halo immobilization device.

Current techniques of stereotactic, small-field, external-beam irradiation with linear accelerators require treatment with a single fraction or only a few fractions of radiation with large single doses per fraction. Using a radiolucent halo that remained affixed to the cranium with skin-piercing screws, the authors treated 24 patients with a multifraction technique for benign and malignant brain lesions. The objective of this study was to ascertain the feasibility of maintaining the halo in place for a prolonged, multifraction course of treatment, not to assess treatment efficacy. The halo was affixed for multifraction treatments lasting 19-58 days (mean, 38.7 days; median, 40.0 days) and delivered in 16-31 fractions (mean, 24.9 fractions; median, 25.5 fractions). Two of 24 patients experienced superficial skin infection at the site of fixation, but no other significant acute or chronic toxicity attributable to the stereotactic halo was observed. The authors conclude that stereotactic, small-field, precision irradiation can be accomplished with multiple fractions as well as with a single fraction.

Adolescent↗