MEG response to median nerve stimulation correlates with recovery of sensory and motor function after stroke

OBJECTIVE

Hemiparesis due to damage by stroke in primary motor cortex (MI) or its underlying projections presents a problem for functional neuroimaging technologies that attempt to evaluate the neurophysiological basis for restoration of motor function. Traditional assessments of MI function require patients to move their fingers, hands, or limbs, which can be either impossible or markedly compromised after stroke. We recently demonstrated in normal subjects that magnetoencephalography (MEG), a non-invasive neuromagnetic functional imaging technique, detects neuronal response elicited by electrical median nerve stimulation in MI, as well as primary somatosensory cortex (SI). In the present study, we used the MEG response from median nerve stimulation to investigate the recovery of primary motor and somatosensory in acute ischemic stroke patients.

METHODS

Twelve patients with unilateral ischemic strokes that affected sensorimotor functions of their hand were studied in the acute stage (4.4+/-1.2 days, mean+/-SD) and during a 1-month follow-up (38.6+/-5.6 days, except for one patient's follow-up done 6 month after stroke).

RESULTS

Among the multiple cortical sources localized after median nerve stimulation, one source localized to SI and another localized to the vicinity of MI. Changes in the source strengths of the first component post-stimulus of MI and SI correlated with the extent of recovery of sensorimotor functions as determined by neurological exams.

CONCLUSIONS

This study provides a novel way of indirectly assessing MI function using MEG during the acute stroke phase, when many patients often cannot perform motor tasks due to paralysis.

Investigation of the normal proximal somatomotor system using magnetoencephalography

OBJECTIVE

The role of the ipsilateral cortex in proximal muscle control in normal human subjects is still under debate. One clinical finding, rapid recovery of proximal muscle relative to distal muscle use following stroke, has led to the suggestion that the ipsilateral as well as the contralateral motor cortex may be involved in normal proximal muscle control. The primary goal of this project was to identify contralateral and ipsilateral motor cortex activation associated with proximal muscle movement in normal subjects using magnetoencephalography (MEG).

METHODS

We developed protocols for a self-paced bicep motor task and a deltoid, electrical-stimulation somatosensory task. The MEG data were analyzed using automated multi-dipole spatiotemporal modeling techniques to localize the sources and characterize the associated timing of these sources.

RESULTS

Reliable contralateral primary motor and somatosensory sources localized to areas consistent with the homunculus. Ipsilateral M1 activation was only found in 2/12 hemispheres.

CONCLUSIONS

Robust contralateral motor cortex activation and sparse ipsilateral motor cortex activation suggest that the ipsilateral motor cortex is not involved in normal proximal muscle control.

SIGNIFICANCE

The results suggest that proximal and distal muscle control is similar in normal subjects in the sense that proximal muscle control is primarily governed by the contralateral motor cortex.

Smallpox and smallpox vaccination: neurological implications

Compulsory vaccination was discontinued in the U.S. in 1972; the world was declared free of smallpox infection in 1980. Since that time, no new smallpox infections have been recognized, and only limited numbers of military and laboratory personnel have been vaccinated. As a result, the majority of the U.S. and the world population have no or diminished immunity to smallpox. Widespread vaccination, beginning with the military and health care workers, is now being undertaken. Public health strategies for immunizing the general population include preexposure voluntary vaccination, case surveillance with ring vaccination, and mass vaccination at the time of attack. Cutaneous complications of vaccination occur in immunosuppressed subjects and in those with atopic dermatitis. Among the most serious complications is postvaccinal encephalomyelitis (PVEM). A related condition, postvaccinial encephalopathy (PVE), may be seen in children less than two years of age. There are no markers to predict who will develop PVEM. In the past, mortality was high, ranging from 10 to 50%. The neuropathology of PVEM suggested an immune-mediated attack on the CNS, but the target of the immune response is unknown. Comprehensive programs are needed for surveillance and confirming case definitions for neurologic complications. Multi-institutional controlled trials of antiviral and immune modulating therapy of PVEM should be considered. Neurologists should be actively involved in the planning process for vaccination programs and in the treatment of neurologic complications.

A partnership of universities and agri-business for an effective dairy herd management learning experience for undergraduates: the Dairy Challenge

The Dairy Challenge contest allows undergraduate students to apply knowledge gained in the classroom in an evaluation of the management practices of commercial dairy farms. University faculty partnered with industry representatives to develop the competition. Participants in the Dairy Challenge do the following: 1) critically evaluate dairy herd management practices and make recommendations for improvements; 2) visit local dairy farms and gain knowledge of different farms' management practices; 3) meet and interact with potential employers from the dairy industry during the contest; 4) evaluate herd records and utilize knowledge of dairy herd management software and computer presentation tools; 5) test their speaking, presentation, and problem-solving skills; and 6) work as a team to build consensus and tag-team speaking formats. Teams of four undergraduate students critically evaluate a commercial dairy farm using herd records, a description of farm operations, and tour of the farm facilities. The farmer answers questions pertaining to management of the farm in a group interview with all teams and in a separate interview with each individual team. Teams give a 20-min presentation that is scored on the description and assessment of the management practices and recommendations for improvements in management and facilities. Additionally, scoring is based on apparent level of preparation, speaking, presentation skills, and responses to judges' questions. The judges are university specialists and dairy industry professionals. This capstone experience allows students to interact with dairy farmers and representatives from the dairy industry and expands their knowledge and skills gained during their academic career.

Botulism

Botulinum toxin is the most potent toxin known to humans and as little as 100 ng can be lethal. The toxin blocks peripheral cholinergic neurotransmission at the neuromuscular junction and cholinergic autonomic nervous system by introducing an endopeptadase enzyme into the presynaptic side of the synapse. The endopeptadase cleaves acetylcholine vesicle docking proteins that are required for the synapse to release acetylcholine into the synaptic cleft. Botulism occurs from consumption or inhalation of preformed botulinum toxin or growth of Clostridium botulinum bacteria in the infant gastrointestinal tract or within a wound. Growth of C. botulinum in the immature gut or wound will release botulinum toxin that reaches the circulation. All forms of botulism cause progressive weakness, bulbar signs (blurred vision, diplopia, mydriasis, dysphagia, and dysarthria), and respiratory failure with normal sensation and mentation. Treatment is aimed at 1) maintaining respiration via intubation and mechanical ventilation, 2) stopping progression of weakness by administration of botulinum antitoxin (equine trivalent botulinum antitoxin for adults and botulism immune-globulin intravenous-human for infant botulism), and 3) preventing complications from weeks of paralysis with good supportive care. The source of the botulinum toxin should be identified to prevent additional cases. Patients can recover normal muscle strength within weeks to months, but usually complain of fatigue for years.

Human T lymphocyte response to Borrelia burgdorferi infection: no correlation between human leukocyte function antigen type 1 peptide response and clinical status

We tested the hypothesis that cross-reactivity between the outer surface protein A (OspA) of Borellia burgdorferi and human leukocyte function antigen (LFA) type 1 mediates chronic autoimmune sequelae of Lyme disease. T cell response was studied in subjects with Lyme disease presenting with erythema migrans alone (n=36), erythema migrans with neurological disease (n=12), and chronic Lyme disease syndrome (n=20), as well as healthy control subjects from Lyme-endemic (n=50) and -nonendemic (n=18) regions. Antigens included recombinant OspA and OspC (all strain B31) and human LFA-1 peptide (IYVIEGTSKQDLTSF). Proliferation to OspA was detected in 11 (28%) of 39 of subjects presenting with erythema migrans, which increased to 50% at 4 weeks of follow-up. Reactivity to OspA and LFA-1 was significantly correlated (P<.001) and was observed in 18 (78%) of 23 of OspA-responsive subjects. However, there was no correlation between T cell response to human LFA-1 peptide and clinical status.

Methanol poisoning exposures in the United States: 1993-1998

OBJECTIVES

We investigated U.S. methanol-poisoning exposures since little recent information is available about the frequency, sources of methanol, or outcomes of individuals who consume methanol.

METHODS

We reviewed human methanol exposures reported to the American Association of Poison Control Centers Toxic Exposure Surveillance System 1993-1998.

RESULTS

The mean number of cases per year was 2254. Each year 167 cases had an outcome of moderate effect, major effect, or death. One death occurred in every 183 exposures to methanol. Symptomatic cases increased abruptly from 1.8 to 2.5% for infants and children, from 14.1 to 12.3% for adolescents and adults, while the intentional exposures increased from < 1 to 21% for adolescents, and 11% for adults. Cases occurred in every decade of life but toddlers had the highest number of exposures. In 68 methanol fatalities, confusion developedfollowed by coma, hypotension, respiratory depression, and cerebral edema. Blood methanol levels were above 100mg/dL (70%), metabolic acidoses (62%), and anion gaps > 25 (100%). Methanol products were recorded, showing windshield wiper fluids to be 60.8% of exposures. Other automotive sources were 23.7%. Commercial nonautomotive products were 12.2% and pure methanol products were 2.3%. Unintentional exposures were reported in 90.3% of all cases, while 8.3% were due to intentional exposures, and 1.4% wasfor unknown or mixed reasons. Intentional exposures resulted from suspected suicides (51.2%) and from abuse and misuse (38.8%).

CONCLUSIONS

Methanol poisonings continue to occur in the United States with toddlers at the highest risk for exposure, but adolescents and adults at the highest risk for life-threatening intoxications. Over half of product-identified cases were due to consumption of windshield wiperfluid. Efforts should be undertaken to minimize methanol exposures.

Biofilm on ventriculo-peritoneal shunt tubing as a cause of treatment failure in coccidioidal meningitis

We describe a case of recurrent coccidioidal meningitis in which a fungal biofilm on the tip of ventriculo-peritoneal shunt tubing was likely responsible for a 4-year persistence of Coccidioides immitis, despite the patient's taking an adequate dosage of fluconazole. Fungal biofilms should be considered as a cause for treatment failure and fungal persistence, especially when artificial prostheses or indwelling catheters are present.

Oculopharyngeal muscular dystrophy in Hispanic New Mexicans

CONTEXT

Oculopharyngeal muscular dystrophy (OPMD) is a rare myopathy caused by polyalanine triplet repeat expansion in the gene for poly(A) binding protein 2 (PABP2) and is found in isolated cohorts throughout the world. We have observed numerous cases of OPMD in New Mexico.

OBJECTIVE

To characterize the clinical, genetic, and demographic features of the OPMD population in New Mexico.

DESIGN, SETTING, AND PARTICIPANTS

Cohort study with analysis of outpatient clinic medical records from 1965 to 2001 at the University of New Mexico Hospital and the New Mexico VA Health Care System in Albuquerque, which serve the entire state.

MAIN OUTCOME MEASURES

Clinical phenotype, supplemented with genetic confirmation (n = 10 patients) and in-depth clinical evaluations (n = 49 patients).

RESULTS

We identified 216 cases of OPMD (99 women and 117 men) from 39 kindreds of New Mexicans spanning up to 4 generations. All patients were Hispanic, and the majority of probands came from northern New Mexico. In patients who had both ocular and pharyngeal muscle weakness, ptosis was just as likely to occur before or concurrent with dysphagia. Proximal limb muscle weakness and gait abnormalities were common and occurred later than ocular or pharyngeal weakness. The clinical expression of OPMD caused marked debility, although life-table analysis showed no decrease in life expectancy compared with unaffected family members (P =.81). Ten individuals from different kindreds were found to have an identical polyalanine triplet repeat expansion ([GCG](9)) in the PABP2 gene.

CONCLUSIONS

Individuals in this cohort had clinical and genetic characteristics of classic OPMD. Longevity was not affected, but patients experienced considerable morbidity. The origin of the PABP2 mutation in New Mexican OPMD patients is unclear, although the geographic and genetic isolation of northern New Mexicans with a long ancestry in this region may have contributed to the development of this cohort. This disease cohort represents a large and previously unrecognized health care issue in the state of New Mexico and should serve to raise the awareness of this disorder among clinicians who treat Hispanics in the Southwest and throughout the United States.

Shingles (Herpes Zoster) and Post-herpetic Neuralgia

During childhood chickenpox, varicella-zoster virus becomes latent in neurons of the dorsal root or trigeminal ganglia. Shingles results years to decades later from a breakdown of viral latency within a ganglion and subsequent virus spread to the skin producing a unilateral dermatomal vesicular rash accompanied by segmental pain. Treatment with famciclovir, valacyclovir, and high dose acyclovir is beneficial if started within the first 3 days of the rash. All three drugs can be given orally, are equally effective, shorten the duration of viral shedding and time to healing of the rash by 1 to 2 days, and lessen the intensity and duration of the acute neuritic pain. Famciclovir and valacyclovir have more convenient dosing schedules (three times daily) compared to acyclovir (five times daily). Mild cases of shingles in younger healthy individuals often do not require any antiviral treatment. Pain in shingles may have burning, lancinating, or allodynic qualities, ranges in intensity from mild to unbearable, and lasts 2 to 8 weeks. Pain treatment varies on the type and intensity of pain experienced. In a few patients, post-herpetic neuralgia develops and the dermatomal pain persists for months to years. Effective treatment of post-herpetic pain is often difficult.

Experimental influenza B viral myositis

To investigate the pathogenesis of influenza myositis in animals, juvenile BALB/c mice were inoculated with influenza B/Lee virus intramuscularly into the right quadriceps muscle. Chicken normal allantoic fluid (NAF) or phosphate-buffered saline (PBS) was injected into the left quadriceps of control mice and in some virus-infected mice. Serum creatinine phosphokinase (CPK) levels rose significantly on days 1 and 2 post-inoculation (PI) in only virus-inoculated mice. On days 2 and 3 PI, right quadriceps muscles developed scattered foci of a predominantly mononuclear inflammation in the perimysial connective tissue often adjacent to degenerating or necrotic muscle fibers. Immunofluorescent staining with specific anti-influenza B virus antisera showed muscle fibers that contained specific staining in nuclei and adjacent cytoplasm. Skip areas of staining within muscle fibers suggested that not all muscle nuclei within an individual muscle fiber were infected. A continuous fall in infectious virus titer in the right quadriceps muscles suggested the initial virus inoculum became inactivated and progeny virions were not produced. Left quadriceps muscle never had muscle necrosis or endomysial inflammation, specific staining of viral antigen, virus isolation, or viral RNA detected by the reverse transcriptase polymerase chain reaction assay. These findings support the hypothesis that a non-permissive influenza viral infection can develop in murine skeletal muscle that can damage specific nuclear domains of muscle fibers producing muscle degeneration or necrosis. A similar type of muscle infection may develop in humans that occasionally develop focal myositis during influenza.

Epidemic typhus meningitis in the southwestern United States

A patient residing in New Mexico had murine typhus diagnosed. A novel molecular assay was performed at the Centers for Disease Control and Prevention, and Rickettsia prowazekii, the agent of epidemic typhus, was found, rather than R. typhi. To our knowledge, this is the first reported case of epidemic typhus confirmed by means of polymerase chain reaction--based testing of cerebrospinal fluid, and it introduces a novel assay for the molecular diagnosis of both epidemic and murine typhus.

Experimental influenza causes a non-permissive viral infection of brain, liver and muscle

To determine whether some constitutional symptoms of influenza, such as headache, myalgia and nausea, could represent a viral infection of brain, muscle, and liver, we inoculated juvenile Balb/c mice intranasally with 103 plaque forming units of influenza B/Lee virus. Blood, brain, liver, skeletal muscle, and lung tissues were removed aseptically and assayed for infectivity by a plaque assay, viral RNA by reverse transcriptase-polymerase chain reaction (RT - PCR), viral antigen by immunoperoxidase staining, and histologic changes by light microscopy. Mice became ill 2 - 3 days post inoculation (PI). A productive viral infection of the lungs developed from days 1 - 8 with maxima of virus titers, pneumonia, and the number of immunoperoxidase staining lung cells occurring on days 2 - 6 PI. Virus isolation from blood was rare and viral RNA was detected intermittently in blood by RT - PCR. In many animals, a non-permissive or abortive infection of brain occurred from days 1 - 8 and peaked on days 3 - 4 PI. Viral RNA was detected in brain tissue and viral antigen was seen in cerebral endothelial cells but infectious virus was rarely isolated from brain. In liver, viral RNA was detected and viral antigen was seen occasionally in hepatocytes. In skeletal muscle, viral RNA was detected but neither infectious virus nor viral antigen was seen. A correlation existed between the severity of the illness, pneumonia, lung virus titer, viral antigen in lung cells, and extent of a non-permissive viral infection of brain and liver but not muscle. These studies demonstrate that following intranasal infection of influenza virus in mice, a viral pneumonia develops with subsequent intermittent viremia and non-permissive or abortive infection of brain, liver and muscle.

Intranuclear inclusions in oculopharyngeal muscular dystrophy contain poly(A) binding protein 2

Intranuclear inclusions are one of the ultrastructural hallmarks of oculopharyngeal muscular dystrophy (OPMD), a disorder caused by small polyalanine (GCG) expansions in the gene that codes for a ubiquitous nuclear protein called poly(A) binding protein 2 (PABP2). We studied OPMD skeletal muscle and found that 1.0 to 10.0% of myocyte nuclei contained discreet PABP2 immunoreactive intranuclear inclusions, providing the first direct evidence of the relation between the proposed gene for OPMD and the pathology of OPMD.

Fungal infections of the central nervous system

This review discusses a practical approach to the patient with possible fungal infection of the central nervous system (CNS). Difficulties in establishing the diagnosis come from the nonspecific clinical syndromes (subacute meningitis, meningoencephalitis, and brain abscess) and the low isolation rate of fungi from cerebrospinal fluid (CSF). Helpful diagnostic clues often come from knowledge of the patient's geographic travels, risk factors, evidence of systemic organ infection, and fungal serologic tests. Standard and new antifungal agents are evaluated and the initial and suppressive drug management of the common fungal infections is presented.

Hemodynamic effects of ionized calcium in horses anesthetized with halothane or isoflurane

OBJECTIVES

To evaluate the effects of halothane and isoflurane on cardiovascular function and serum total and ionized calcium concentrations in horses, and to determine whether administration of calcium gluconate would attenuate these effects.

ANIMALS

6 clinically normal adult Thoroughbreds.

PROCEDURE

Catheters were inserted for measurement of arterial blood pressures, pulmonary arterial blood pressures, right ventricular pressure (for determination of myocardial contractility), right atrial pressure, and cardiac output and for collection of arterial blood samples. Anesthesia was then induced with xylazine hydrochloride and ketamine hydrochloride and maintained with halothane or isoflurane. An i.v. infusion of calcium gluconate was begun 75 minutes after anesthetic induction; dosage of calcium gluconate was 0.1 mg/kg of body weight/min for the first 15 minutes, 0.2 mg/kg/min for the next 15 minutes, and 0.4 mg/kg/min for an additional 15 minutes. Data were collected before, during, and after administration of calcium gluconate.

RESULTS

Halothane and isoflurane decreased myocardial contractility, cardiac index, and mean arterial pressure, but halothane caused greater depression than isoflurane. Calcium gluconate attenuated the anesthetic-induced depression in cardiac index, stroke index, and maximal rate of increase in right ventricular pressure when horses were anesthetized with isoflurane. When horses were anesthetized with halothane, a higher dosage of calcium gluconate was required to attenuate the depression in stroke index and maximal rate of increase in right ventricular pressure; cardiac index was not changed with calcium administration.

CONCLUSIONS AND CLINICAL RELEVANCE

I.v. administration of calcium gluconate may support myocardial function in horses anesthetized with isoflurane.

Myocardial blood flow and coronary reserve in chronically anemic fetal lambs

Chronic fetal anemia produces large compensatory increases in coronary blood flow in the near-term fetal lamb. To determine if increased coronary flow in anemic fetuses is associated with decreased coronary flow reserve or, alternatively, an increase in coronary conductance, we measured maximal coronary artery conductance during adenosine infusion before and during anemia. Isovolemic hemorrhage over 7 days reduced hematocrit from 30.6 +/- 2. 7 to 15.8 +/- 2.4% (P < 0.02) and the oxygen content from 7.3 +/- 1. 4 to 2.6 +/- 0.4 ml/dl (P < 0.001). Coronary blood flow increased from control (202 +/- 60) to 664 +/- 208 ml. min(-1). 100 g(-1) with adenosine to 726 +/- 169 ml. min(-1). 100 g(-1) during anemia and to 1,162 +/- 250 ml. min(-1). 100 g(-1) (left ventricle) during anemia with adenosine infusion (all P < 0.001). Coronary conductance, determined during maximal vasodilation, was 18.2 +/- 7.7 before and 32.8 +/- 11.9 ml. min(-1). 100 g(-1). mmHg(-1) during anemia (P < 0. 001). Coronary reserve, the difference between resting and maximal myocardial blood flow interpolated at 40 mmHg, was unchanged in control and anemic fetuses (368 +/- 142 and 372 +/- 201 ml/min). Because hematocrit affects viscosity, anemic fetuses were transfused with blood to acutely increase the hematocrit back to control, and conductance was remeasured. Coronary blood flow decreased 57.3 +/- 18.9% but was still 42.6 +/- 18.9% greater than control. We conclude that in chronically anemic fetal sheep coronary conductance is increased and coronary reserve is maintained, and this is attributed in part to angiogenesis as well as changes in viscosity.

Techniques for evaluation of right ventricular relaxation rate in horses and effects of inhalant anesthetics with and without intravenous administration of calcium gluconate

OBJECTIVES

To determine the most repeatable method for evaluating right ventricular relaxation rate in horses and to determine and compare effects of isoflurane or halothane with and without the added influence of intravenously administered calcium gluconate on right ventricular relaxation rates in horses.

ANIMALS

6 Thoroughbred horses from 2 to 4 years old.

PROCEDURE

6 models (2 for monoexponential decay with zero asymptote, 3 for monoexponential decay with variable asymptote, and 1 for biexponential decay) for determining right ventricular relaxation rate were assessed in conscious and anesthetized horses. The 2 methods yielding the most repeatable results then were used to determine right ventricular relaxation rates in horses anesthetized with isoflurane or halothane before, during, and after i.v. administration of calcium gluconate. Right ventricular pressure was measured, using a catheter-tip high-fidelity pressure transducer, and results were digitized at 500 Hz from minimum rate of change in ventricular pressure.

RESULTS

2 models that used monoexponential decay with zero asymptote repeatedly produced an estimate for relaxation rate and were used to analyze effects of anesthesia and calcium gluconate administration on relaxation rate. Isoflurane and halothane each prolonged right ventricular relaxation rate, with greater prolongation evident in halothane-anesthetized horses. Calcium gluconate attenuated the anesthesia-induced prolongation in right ventricular relaxation rate, with greater response obtained in isoflurane-anesthetized horses.

CONCLUSIONS AND CLINICAL RELEVANCE

Right ventricular relaxation rate in horses is assessed best by use of a monoexponential decay model with zero asymptote and nonlinear regression. Intravenous administration of calcium gluconate to isoflurane-anesthetized horses best preserves myocardial relaxant function.

Differentiation of atrioventricular blocks

In closing, it has been the purpose of this article to present and elaborate on the types of AV blocks, their clinical significance and causes, nursing interventions, and treatments associated with their management. The nurse that has knowledge of these heart blocks will be well equipped and prepared to promptly treat a patient suffering from AV block.

Autosomal dominant cerebral arteriopathy: neuropsychiatric syndrome in a family

Though familial vascular leukoencephalopathy was described two decades ago, recent studies focus on a disorder termed Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL), a dominantly inherited disorder causing recurrent strokes and eventual dementia. The phenotypic boundaries of CADASIL remain indistinct and novel clinical features continue to arise in the literature. However, the associated histopathology is fairly consistent, typically demonstrating granular thickening of cerebral arterioles. The authors evaluated a 38-year-old man who suffered from progressive change in personality and intellect. His father, paternal aunt, and older sister had succumbed to a similar disorder. The authors examined relatives from three generations, including another sister with transient focal symptoms followed by persisting psychiatric disorder, and reviewed the radiographic studies from the propositus and his siblings. All the siblings showed diffuse white matter signal change on magnetic resonance imaging. Brain biopsy from the propositus revealed normal cortex and white matter but granular sclerosis of leptomeningeal arterioles. While the family's illness likely represents another instance of CADASIL, their presentation is unique because neuropsychiatric disorders predominate over focal ischemic symptoms.

Ascertaining hypoglycorrhachia in an acute patient

A study was undertaken in an urgent clinical setting to determine whether the use of a cerebrospinal fluid (CSF) to blood glucose ratio is appropriate for describing the relationships between CSF glucose and blood glucose in patients who had not fasted. Blood glucose levels were obtained before a lumbar puncture in 79 adults who had normal CSF findings. Regression analysis of CSF glucose and blood glucose levels of these patients who had not fasted, as well as data from four published studies of normal blood and CSF glucose levels, indicated that a ratio was not a valid measure of the normal relationship between CSF and blood. Only when the blood glucose level was between 89 and 115 mg/dL was the relationship within the expected "ratio" of 0.60 to 0.70. In hyperglycemic states, the normal relationship may be substantially lower than 0.50. a nomogram is presented which is useful in determining hypoglycorrhachia when the patient is hyperglycemic.

Office procedures. No-scalpel vasectomy

Vasectomy is a safe, permanent, and inexpensive method of surgical sterilization for men. No-scalpel vasectomy is an innovative approach for exposing the vas deferens that is associated with fewer complications than the standard technique of vasectomy (incisional). It has been used in this country since 1986. The no-scalpel vasectomy, preoperative counseling, management of complications, and evaluation of the postvasectomy semen specimen are described.

Purine metabolism and inhibition of xanthine oxidase in severely hypoxic neonates going onto extracorporeal membrane oxygenation

The effect of allopurinol to inhibit purine metabolism via the xanthine oxidase pathway in neonates with severe, progressive hypoxemia during rescue and reperfusion with extracorporeal membrane oxygenation (ECMO) was examined. Twenty-five term infants meeting ECMO criteria were randomized in a double-blinded, placebo-controlled trial. Fourteen did not receive allopurinol, whereas 11 were treated with 10 mg/kg after meeting criteria and before cannulation, in addition to a 20-mg/kg priming dose to the ECMO circuit. Infant plasma samples before cannulation, and at 15, 30, 60, and 90 min, and 3, 6, 9, and 12 h on bypass were analyzed (HPLC) for allopurinol, oxypurinol, hypoxanthine, xanthine, and uric acid concentrations. Urine samples were similarly evaluated for purine excretion. Hypoxanthine concentrations in isolated blood-primed ECMO circuits were separately measured. Hypoxanthine, xanthine, and uric acid levels were similar in both groups before ECMO. Hypoxanthine was higher in allopurinol-treated infants during the time of bypass studied (p = 0.022). Xanthine was also elevated (p < 0.001), and uric acid was decreased (p = 0.005) in infants receiving allopurinol. Similarly, urinary elimination of xanthine increased (p < 0.001), and of uric acid decreased (p = 0.04) in treated infants. No allopurinol toxicity was observed. Hypoxanthine concentrations were significantly higher in isolated ECMO circuits and increased over time during bypass (p < 0.001). This study demonstrates that allopurinol given before cannulation for and during ECMO significantly inhibits purine degradation and uric acid production, and may reduce the production of oxygen free radicals during reoxygenation and reperfusion of hypoxic neonates recovered on bypass.

Hemodynamic effects of calcium gluconate administered to conscious horses

Calcium gluconate was administered to conscious horses at 3 different rates (0.1, 0.2, and 0.4 mg/kg/min for 15 minutes each). Serum calcium concentrations and parameters of cardiovascular function were evaluated. All 3 calcium administration rates caused marked increases in both ionized and total calcium concentrations, cardiac index, stroke index, and cardiac contractility (dP/dtmax). Mean arterial pressure and right atrial pressure were unchanged; heart rate decreased markedly during calcium administration. Ionized calcium concentration remained between 54% and 57% of total calcium concentration throughout the study. We conclude that calcium gluconate can safely be administered to conscious horses at 0.1 to 0.4 mg/kg/min and that administration will result in improved cardiac function.

Enhanced diallyl trisulfide has in vitro synergy with amphotericin B against Cryptococcus neoformans

Although amphotericin B remains the drug of choice for systemic fungal infections, its use is limited by considerable side effects. In The Peoples' Republic of China, commercial Allium sativum derived compounds are widely used as an antifungal drug to treat systemic fungal infections. To evaluate the scientific merit of using A. sativum derived compounds as antifungal agents, we studied a Chinese commercial preparation, allitridium. This preparation contained mainly diallyl trisulfide as confirmed by high performance liquid chromatography. Allitridium, with and without amphotericin B, was tested to determine its efficacy in killing three isolates of Cryptococcus neoformans. The minimum inhibitory concentration of the commercial preparation was 50 micrograms/ml and the minimum fungicidal concentration was 100 micrograms/ml against 1 x 10(5) organisms of C. neoformans. In addition, the commercial preparation was shown to be synergistic with amphotericin B in the in vitro killing of C. neoformans. This study demonstrates that diallyl trisulfide and other polysulfides possess potent in vitro fungicidal effects and their activity is synergistic with amphotericin B. These observations lend laboratory support for the treatment of cryptococcal infections with both amphotericin B and the Chinese commercial preparation.

Renal responses to amino acids in the sheep fetus

Adult animals and humans are known to increase renal blood flow and glomerular filtration rate (GFR) in response to an acute protein load or amino acid infusion; however, the ontogeny of this phenomenon is not known. This study was designed to test the hypothesis that, despite normally high baseline amino acid levels in the fetus, increases in plasma amino acids stimulate increases in GFR before birth. Eight chronically instrumented fetal sheep (126 +/- 1 days gestation) were infused with a mixture of amino acids (0.15 and 0.30 mmol . kg-1 . min-1 i.v.). Plasma alpha-amino nitrogen levels increased significantly from 7.1 +/- 0.3 to 13.0 +/- 0.9 and 25.5 +/- 2.1 mg/dl, respectively, in response to the two doses, and GFR increased significantly from 3.2 +/- 0.4 to 4.0 +/- 0.5 and 4.6 +/- 0.5 ml/min, respectively. Arterial pressure did not change. Renal amino acid reabsorption was significantly increased at all time points during the amino acid infusion, reaching a value nearly five times that of control by the last clearance period. Na+ reabsorption was also increased throughout the infusion. Na+, K+, and Cl- excretions increased significantly only at the very last time point. These data indicate that the mechanism or mechanisms responsible for amino acid-induced hyperfiltration are present and functional even before birth in the sheep. Because maternal eating patterns and protein intake are known to change maternal plasma amino acid levels and amino acids are actively transported across the placenta, our findings suggest that both acute and chronic changes in maternal protein intake may alter fetal renal function.

Changes in left thoracic duct lymph flow during progressive anemia in the ovine fetus

OBJECTIVE

The purpose of this study was to evaluate the extent to which increased lymph flow can return fluid and protein to the circulation in the chronically anemic fetus.

STUDY DESIGN

Thoracic duct lymph flow rate over a range of outflow pressures was measured in 8 near-term fetal sheep 4 to 5 days after surgery and daily thereafter for 5 days. After each day's study 60 to 150 ml of blood was withdrawn at a rate of 1 ml per minute. Regression analysis was used to establish the lymph flow function curve. Lymph and plasma protein concentrations and lymph flow rate were compared by analysis of variance for repeated measures.

RESULTS

As the hematocrit was reduced from 34.6% +/- 1.3% (mean +/- SE) to 14.4% +/- 1.0%, thoracic duct lymph flow increased from 0.12 +/- 0.01 to 0.28 +/- 0.02 ml/min/kg. Plasma total protein concentration did not change, lymph protein concentration fell (2.6 +/- 0.1 to 2.4 +/- 0.1 gm/dl), and the difference between plasma and lymph protein concentrations increased (1.04 +/- 0.05 to 1.34 +/- 0.10 gm/dl). Protein returned to the circulation increased from 11.5 +/- 0.3 to 23.7 +/- 1.5 mg per minute. Central venous pressure did not change and remained less than the breakpoint pressure. Although the plateau lymph flow rate increased, neither the breakpoint or stopflow pressures of the lymph flow function curve were altered.

CONCLUSIONS

Fetal lymph flow and thereby capillary filtration increased progressively as anemia became more severe. The increase in lymph flow did not appear to be limited by outflow pressure. By returning protein to the circulation, an increase in thoracic duct lymph flow helped to limit expansion of extravascular fluid volume during chronic fetal anemia.

Right ventricular function in chronically anemic fetal lambs

OBJECTIVE

Our purpose was to determine whether the increase in extravascular fluid in chronic fetal anemia occurs either because of heart failure or despite successful cardiac adaptation.

STUDY DESIGN

Right ventricular function curves were obtained in five ovine fetuses at the start, midpoint, and end of 5 to 8 days of anemia induced by isovolemic daily hemorrhage. Least-squares fit of the ascending and plateau lines of stroke volume versus right atrial pressure were used to establish breakpoints (intersection of the ascending and plateau lines), which were compared by analysis of variance for repeated measures. Myocardial blood flow was measured by microspheres.

RESULTS

Carotid arterial oxygen content was reduced from 7.0 +/- 0.3 to 2.1 +/- 0.1 ml/dl and the hematocrit from 29% +/- 1.8% to 13% +/- 0.6%. Breakpoint analysis of function curves showed that although right atrial pressure remained unchanged (3.4 +/- 0.7 and 3.6 +/- 0.6 mm Hg) stroke volume increased from 1.03 +/- 0.14 to 1.62 +/- 0.25 ml/kg. Both right and left ventricular coronary blood flow were increased, 1351 +/- 313 and 1166 +/- 264 ml/min per 100 gm. Excess fluid was present in abdomen and chest of most animals at autopsy.

CONCLUSION

Tissue edema during severe anemia occurs despite normal right atrial pressure, increased stroke volume, and markedly increased coronary blood flow, markers of successful cardiac adaptation.

Clinical Viral Infections and Temporal Bone Histologic Studies of Patients with AIDS

The brain, eye, and inner ear are each protected from blood-borne infectious agents by a barrier that has some anatomic and functional differences. In patients with AIDS, opportunistic infections of the central nervous system and eye are frequent. Little is known about the incidence of middle and inner ear infections in patients with AIDS, but deafness and severe vertigo are uncommon. We studied 14 homosexual men with AIDS, aged 28 to 55 years, for 1 to 2 years until death. No patient had deafness, but one had vertigo. Adenovirus type 6 and cytomegalovirus were isolated from the middle ear cavity in four patients. Temporal bone histology demonstrated acute otitis media in four, chronic otitis media in two, and serous otitis media in three. Adenovirus type 6 and cytomegalovirus, either alone or with herpes simplex virus type 1, were isolated from inner fluids of three patients. Histologic inner ear findings were abnormal in only one patient. Viruses were isolated or histologically identified in the brains of four patients and in the eyes of five patients. In our patients viral infections were nearly as common in the inner ears as in the brain and eye, suggesting that protection from the blood-labyrinth barrier was similar to that from the other barriers. Because the inner ear viral infections were asymptomatic and there was an absence of pathologic damage and inflammation, we suggest that some viral inner ear infections in patients with AIDS are nonpathogenic and elicit no inflammation or that the viral infections occur terminally and elicit no inflammation because of immunosuppression from the AIDS.

Clinical viral infections and temporal bone histologic studies of patients with AIDS

The brain, eye, and inner ear are each protected from blood-borne infectious agents by a barrier that has some anatomic and functional differences. In patients with AIDS, opportunistic infections of the central nervous system and eye are frequent. Little is known about the incidence of middle and inner ear infections in patients with AIDS, but deafness and severe vertigo are uncommon. We studied 14 homosexual men with AIDS, aged 28 to 55 years, for 1 to 2 years until death. No patient had deafness, but one had vertigo. Adenovirus type 6 and cytomegalovirus were isolated from the middle ear cavity in four patients. Temporal bone histology demonstrated acute otitis media in four, chronic otitis media in two, and serous otitis media in three. Adenovirus type 6 and cytomegalovirus, either alone or with herpes simplex virus type 1, were isolated from inner fluids of three patients. Histologic inner ear findings were abnormal in only one patient. Viruses were isolated or histologically identified in the brains of four patients and in the eyes of five patients. In our patients viral infections were nearly as common in the inner ears as in the brain and eye, suggesting that protection from the blood-labyrinth barrier was similar to that from the other barriers. Because the inner ear viral infections were asymptomatic and there was an absence of pathologic damage and inflammation, we suggest that some viral inner ear infections in patients with AIDS are nonpathogenic and elicit no inflammation or that the viral infections occur terminally and elicit no inflammation because of immunosuppression from the AIDS.

Role of endogenous atrial natriuretic peptide in chronic anemia in the ovine fetus: effects of a non-peptide antagonist for atrial natriuretic peptide receptor

Chronic fetal anemia causes polyhydramnios and fetal hydrops and is associated with increased fetal diuresis and natriuresis. To determine the role of atrial natriuretic peptide (ANP) in the renal adaptation to chronic fetal anemia we studied the effects of HS-142-1 (HS), a specific inhibitor of the guanylate cyclase-linked ANP receptor (ANP-GC), in two groups of chronically instrumented unanesthetized sheep fetuses. Seven fetuses were made anemic by serial isovolemic hemorrhage over 1 wk, and five fetuses served as nonanemic controls. Over the 7 d of hemorrhage ANP concentrations increased (45 +/- 7 to 234 +/- 15 fmol/mL). Hematocrit and arterial blood oxygen content were significantly lower in the anemic compared with the nonanemic fetuses (13.8 +/- 0.7 versus 34.6 +/- 2.3% and 0.7 +/- 0.1 versus 2.6 +/- 0.2 mmol/L). Before HS urine flow rate, urinary sodium excretion, fractional excretion of sodium, and renal blood flow were increased in the anemic fetuses, and the extracellular fluid volume (inulin space) was increased (674 +/- 94 versus 497 +/- 71 mL/kg). However, GFR was not different between the groups. HS caused a significant increase in the central venous pressure of the anemic fetuses (0.49 +/- 0.03 to 0.70 +/- 0.05 kPa). Urinary excretion of cGMP was considered to be a marker of endogenous ANP renal effect and was measured before and after a single bolus of HS (5.2 +/- 0.30 mg/kg). HS decreased urinary cGMP excretion to 50 and 37% of baseline levels in anemic and nonanemic fetuses, respectively. Urine flow decreased in both nonanemic and anemic fetuses (0.48 +/- 0.13 to 0.25 +/- 0.06 and 1.30 +/- 0.66 +/- 0.06 mL/min). Sodium excretion decreased in both groups after HS (19 +/- 5 to 9 +/- 2 and 83 +/- 16 to 39 +/- 5 mumol/min). GFR decreased after HS (3.0 +/- 0.8 to 2.4 +/- 0.5 and 3.6 +/- 0.3 to 2.6 +/- 0.2 mL/min. Fraction excretion of sodium also decreased in both groups after HS (4.6 +/- 2.7 to 2.7 +/- 0.5 and 16.1 +/- 2.4 to 11 +/- 1.6). Percent decreases in urine flow, sodium excretion, GFR, and fractional excretion of sodium observed in the anemic fetuses were not statistically different from the nonanemic fetuses. Urine flow and sodium excretion did not decrease to control levels after HS, suggesting that factors in addition to ANP contribute to the natriuresis seen with chronic anemia. After HS a transient increase in renal blood flow was observed in the nonanemic fetuses. An immediate and sustained further increase in renal blood flow was observed in the anemic fetuses (336 +/- 37 to 436 +/- 58 mL/min/100 g of kidney). Decreasing GFR and increasing renal blood flow suggests HS may alter the renal microcirculation by reversing ANP-induced constriction of the glomerular efferent arteriole. We conclude that sustained increases of the central venous pressure suggest that ANP inhibition results in decreased fluid movement into perivascular tissue. Endogenous ANP may help to maintain basal renal function in the normal fetal kidney and participates in the renal adaptation to chronic fetal anemia. ANP may promote urine flow and sodium excretion by its effects on both the renal microcirculation and the sodium reabsorptive capacity of the nephron.

Refined localization of the cerebral cavernous malformation gene (CCM1) to a 4-cM interval of chromosome 7q contained in a well-defined YAC contig

Cerebral cavernous malformations (CCM) are vascular lesions present in some 20 million people worldwide that are responsible for seizures, migraine, hemorrhage, and other neurologic problems. Familial cases ofCCM can be inherited as an autosomal dominant disorder with variable expression. A gene for CCM (CCM/)was recently mapped to a 33-cM segment of chromosome 7q in a large Hispanic family (Dubovsky et al.1995). Here, the collection of several new short tandem repeat polymorphisms (STRPs) within the region of interest on 7q and the refinement of the marker order in this region using both linkage analysis in CEPH families and especially YAC-based STS content mapping are described. Affected members of three Hispanic families share allele haplotypes indicating a common ancestral mutation within these families. Using the shared haplotype information along with analysis of crossovers in affected individuals from both the Hispanic and Caucasian families, the region likely to contain the CCMI gene has been reduced to a 4-cM segment of 7q between D7S2410 and D7S689. All markers within the refined chromosomal segment were located on a single YAC contig estimated to be approximately 2 Mb in size. Four potential candidate genes have been mapped to this region.

A locus for cerebral cavernous malformations maps to chromosome 7q in two families

Cavernous malformations (angiomas) affecting the central nervous system and retina can be inherited in autosomal dominant pattern (OMIM 116860). These vascular lesions may remain clinically silent or lead to a number of neurological symptoms including seizure, intracranial hemorrhage, focal neurological deficit, and migraine. We have mapped a gene for this disorder in two families, one of Italian-American origin and one of Mexican-American origin, to markers on proximal 7q, with a combined maximum lod score of 3.92 (theta of zero) with marker D7S479. Haplotype analysis of these families places the locus between markers D7S502 proximally and D7S515 distally, an interval of approximately 41 cM. The location distinguishes this disorder from an autosomal dominant vascular malformation syndrome where lesions are primarily cutaneous and that maps to 9p21.

An MRI study of lumbar puncture headaches

We studied 11 patients undergoing a routine lumbar puncture to determine if there were cerebrospinal fluid leaks at the puncture site and whether the maximum volume of leakage correlates with a lumbar puncture headache. Patients completed a headache questionnaire before and after the lumbar puncture. Limited magnetic resonance imaging of the lumbar spine was obtained 8 to 36 hours after the lumbar puncture and two patients also had later imaging. In a blinded fashion, the largest diameter of cerebrospinal fluid leakage into the paraspinous area was determined from T2 weighted magnetic resonance images and the maximum possible fluid volume was calculated. Six patients had a small cerebrospinal fluid leakage (< 10 mL), two had a medium leakage (10 to 110 mL), and three had a large leakage (> 110 mL). The volume of cerebrospinal fluid leakage did not correlate with occurrence of a lumbar puncture headache. The study demonstrates that cerebrospinal fluid usually leaks into the paraspinous area after a lumbar puncture, but the volume of escaped fluid does not correlate with a lumbar puncture headache.

The vasculopathy of varicella-zoster virus encephalitis

Varicella-zoster virus (VZV) encephalitis has become more prevalent in the era of acquired immunodeficiency syndrome and other immunosuppressive diseases and poses diagnostic and therapeutic challenges for clinicians, radiologists, and pathologists. Six cases studied at our institutions shed light on the patterns and pathogenesis of the disease. VZV encephalitis is predominantly a vasculopathy, involving small and large vessels, that generates seizures, mental changes, and focal deficits. Brain imaging reveals large and small ischemic or hemorrhagic infarcts, often both, of cortex and subcortical gray and white matter. Deep-seated white matter lesions often predominate and are ischemic and/or demyelinative, depending on the size of blood vessels involved and the amount of additional demyelination caused by infection of oligodendrocytes. The demyelinative lesions are smaller and less coalescent than those seen in progressive multifocal leukoencephalopathy.

Neurologic manifestations of intravascular lymphomatosis

Intravascular lymphomatosis is a rare fatal neoplasm characterized by malignant cells of lymphocytic lineage producing vascular occlusions. The cerebral vasculature is particularly affected. Two patients seen at our institution presented with progressive neurologic deficits including dementia, hemiparesis and myelopathy. Review of an additional 64 reported cases with neurologic involvement indicates that patients developed intermittent fevers, an encephalopathy ranging from acute disorientation to rapidly progressive dementia, and focal signs such as hemiparesis and myelopathy. Common laboratory abnormalities include elevated cerebrospinal fluid protein and a lymphocytic pleocytosis, elevated blood erythrocyte sedimentation rate and serum lactate dehydrogenase. Malignant cells are rarely seen in cerebrospinal fluid, blood or bone marrow. Neuroimaging is usually abnormal with parenchymal lesions seen on cerebral tomography and magnetic resonance imaging along with an occasional meningeal pattern of contrast enhancement. Treatment with corticosteroids, chemotherapy, radiation therapy, or plasmapheresis provided limited benefit. Intravascular lymphomatosis should be considered in the differential diagnosis of unexplained progressive encephalopathy with superimposed focal deficits.

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.

In vitro synergism of concentrated Allium sativum extract and amphotericin B against Cryptococcus neoformans

Allium sativum (garlic) derived preparations are used alone or with amphotericin B in Asia to treat human systemic fungal infections and cryptococcal meningitis. To evaluate the scientific merit of using allicin-derived compounds as an anti-fungal drug, we prepared a concentrated A. sativum extract that contained 34% allicin, 44% total thiosulfinates, and 20% vinyldithiins. We found that the concentrated extract possessed potent in vitro fungistatic and fungicidal activity against 3 different isolates of Cryptococcus neoformans. The minimum inhibitory concentration of the concentrated garlic extract against 1 x 10(5) organisms of C. neoformans ranged from 6 to 12 micrograms/ml. In addition, in vitro synergistic fungistatic activity with amphotericin B was demonstrated against all isolates of C. neoformans. This study lends laboratory support for the treatment of cryptococcal infections with concentrated garlic extracts.

Somatosensory evoked magnetic fields in patients with stroke

We used magnetoencephalography to evaluate areas of sensory cortex in patients with ischemic strokes involving the somatomotor system. We measured somatosensory evoked magnetic fields using a 7-channel neuromagnetometer and estimated the location of cortical responses to median nerve stimulation in 5 patients with cortical or subcortical strokes involving the somatomotor system. All patients underwent quantitative neurological examinations and a high resolution volumetric magnetic resonance imaging. The estimated current dipoles were localized onto the patient's own MRI scan in all patients with measurable responses. The location of the estimated dipole was always in non-infarcted tissue in the anatomical region of the somatosensory cortex. In 1 patient the somatosensory dipole localized to a peninsula of cortex flanked by infarcted tissue. Single photon emission computed tomography found the localized area of cortex to have significant blood flow. The estimated current dipole strengths of somatosensory evoked fields from median nerve stimulation correlated significantly (r = 0.95, P < 0.02) with the patient's ability to recognize numbers written on the involved palm (graphesthesia). The combination of evoked magnetic field recording and magnetic resonance imaging is a promising non-invasive technology for studying brain function in patients with cerebrovascular disease.

The pharmacokinetics of injectable allopurinol in newborns with the hypoplastic left heart syndrome

OBJECTIVE

The purpose of this investigation was to determine the pharmacokinetic disposition of intravenous allopurinol and its metabolite oxypurinol in neonates with the hypoplastic left heart syndrome (HLHS) and to evaluate the subsequent degree of xanthine oxidase inhibition using serum uric acid as a marker.

METHODS

Pharmacokinetic data were evaluated in 12 stable preoperative neonates with HLHS after a single intravenous allopurinol administration of 5 mg/kg or 10 mg/kg. Pharmacokinetic parameters were determined for elimination half-life, clearance, volume of distribution, and mean residence time. Xanthine oxidase inhibition, measured by serum uric acid reduction, was also measured.

RESULTS

Pharmacokinetic parameters revealed no statistically significant differences between a 5-mg/kg and 10-mg/kg dose of intravenous allopurinol on elimination half-life, clearance, volume of distribution, and mean residence time. Mean serum uric acid levels were significantly reduced from baseline by 39.99 and 42.94%, respectively, in the 5- and 10-mg/kg treatment groups.

DISCUSSION

The enzyme xanthine oxidase plays a key biochemical role in the generation of toxic oxygen-derived free radicals during ischemia-reperfusion conditions. Allopurinol and its active metabolite oxypurinol inhibit xanthine oxidase, and significantly reduce the conversion of hypoxanthine to xanthine and xanthine to uric acid. Cell injury may be caused by toxic oxygen free radicals produced by ischemia-reperfusion injury such as could occur during the repair of HLHS under hypothermic total circulatory arrest. We hypothesize that allopurinol may provide protection from cellular injury in this clinical context.

Dizziness in elderly men

OBJECTIVE

To evaluate the causes of dizziness in elderly men.

DESIGN

A descriptive study involving the clinical and laboratory features of elderly men with dizziness.

SETTING

A university-affiliated Veterans Affairs medical center.

PATIENTS

One hundred seventeen consecutive men more than 50 years of age attending a general neurology clinic with the chief complaint of dizziness.

RESULTS

The median duration of dizziness at first office visit was 45 weeks. Forty-nine percent of patients had more than one diagnosis that contributed to their dizziness. Dysfunctions of the peripheral vestibular system were found in 71% and were the principal causes in 56%. Benign positional vertigo was present in 34%. Disorders of the visual system were found in 26% but were the major cause in only 1%. Diagnoses involving the proprioceptive system were present in 17% and were the principal cause in 7%. Structural lesions of the brainstem or cerebellum or metabolic disorders that affected normal brainstem function were identified in 59% and were the major diagnoses in 22%. A psychophysiologic diagnosis was made in 6% but was the major diagnosis in only 3%. At the 6-months follow-up, 55% of patients improved, 34% were unchanged, 4% worsened, and 7% were lost to follow-up.

CONCLUSIONS

Contrary to reports in the literature, dizziness in the elderly is more persistent, has more causes, is less often due to a psychophysiologic cause, and seems to be more incapacitating than dizziness in younger patients.

HIV-1 infection despite immediate combination antiviral therapy after infusion of contaminated white cells

We present a sixth human case in which primary human immunodeficiency virus (HIV-1) infection occurred, despite antiretroviral prophylaxis, after accidental inoculation of infected blood. In the prior five instances, variables such as large virus dose, late administration of antivirals, viral resistance to zidovudine, and pre-existent immunosuppression, may have played a role in the treatment failure. In this case, high-dosage oral zidovudine was given within minutes of the accident and replaced 2 1/2 days later with interferon alpha and dideoxyinosine (ddl). Despite aggressive treatment, HIV-1 infection was demonstrated in blood, spleen, and brain tissue at autopsy 16 days later. Of the tissues studied, detection of HIV-1 was most prominent in the spleen. Double-label immunocytochemistry confirmed the morphologic impression that while some of the infected spleen cells were CD3-positive T cells, the majority were macrophages. Thus, current single or dual (zidovudine, ddl-interferon) therapies for accidental HIV-1 inoculation may not be effective in preventing early infection. Further trials in animals appear warranted to evaluate protection by other strategies, such as passive immunity or combinations of agents that penetrate the brain and attack HIV-1 viral replication at differing sites.