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.

Cisplatin: a clinical review. Part I--Current uses of cisplatin and administration guidelines

Cisplatin is one of the most active cancer treatment agents available. Unfortunately, however, cisplatin causes many untoward side effects. Nurses play a major role in administering cisplatin and in preventing and managing the adverse effects associated with this drug. In order to maximize the quality of life of patients undergoing cisplatin treatment, nurses need a thorough knowledge of its uses, administration, and side effects. This article is the first of a two-part series about cisplatin. Part I will provide a review of the mechanism of action, current uses, and administration guidelines. Part II will discuss the most common side effects of cisplatin and the appropriate nursing assessment and management of patients undergoing treatment with this agent. In addition, future directions for the use of cisplatin and the use of alternative agents will be discussed.

Danger of corticosteroid administration in meningitis due to misdiagnosed agent

A 3 1/2-year-old child with acute tuberculous meningitis was misdiagnosed as having "partially treated" meningitis and was treated with ampicillin, chloramphenicol, and dexamethasone. She developed obstructive hydrocephalus and miliary spread of tuberculosis which led to death. It is likely that failure to consider alternative diagnoses promptly and the use of corticosteroids along with ineffective antibiotics contributed to the outcome. Although they may lessen some complications of bacterial meningitis, the indiscriminate use of corticosteroids in misdiagnosed bacterial meningitis may be detrimental.

Renal function during chronic anemia in the ovine fetus

Our purpose was to determine how prolonged anemia alters fetal renal function and acid-base balance. In seven ovine fetuses made progressively anemic over 1 wk by serial isovolemic hemorrhage, hematocrit was reduced from 33.3 +/- 4.5 to 14.0 +/- 1.0%. Femoral arterial oxygen content was less and renal plasma flow was greater in anemic fetuses (1.5 +/- 0.1 ml/dl and 339 +/- 58 ml.min-1.100 g kidney-1) than in 6 control fetuses (7.0 +/- 1.3 ml/dl and 160 +/- 34 ml.min-1.100 g kidney-1). Urine flow and sodium excretion were also greater in anemic fetuses (1.2 +/- 0.6 ml/min and 79 +/- 49.5 mumol/min) than in controls (0.5 +/- 0.2 ml/min and 16 +/- 9.8 mumol/min). This higher sodium excretion was apparently due to a lower fractional sodium reabsorption in anemic fetuses compared with controls (84.1 +/- 5.8 vs. 96.5 +/- 1.7%), rather than to differences in either glomerular filtration rate or amount of filtered sodium. In addition, the higher sodium excretion in anemic fetuses was associated with greater urinary lactate and inorganic phosphate excretions and larger amniotic fluid volumes than in controls. From these data we conclude that when fetal renal oxygen delivery is limited by a prolonged reduction in hematocrit, excretions of sodium and water, as well as other osmotically active solutes, increase, and this results in an increase in amniotic fluid volume.

Methylmercury poisoning: long-term clinical, radiological, toxicological, and pathological studies of an affected family

For 3 months in 1969 a family in the United States that included a pregnant mother consumed pork containing methylmercury. Children, aged 20, 13, and 8 years and a neonate, developed severe neurological signs. Twenty-two years later, the 2 oldest had cortical blindness or constricted visual fields, diminished hand proprioception, choreoathetosis, and attentional deficits. Magnetic resonance images showed tissue loss in the calcarine and parietal cortices and cerebellar folia. The youngest had quadriplegia, blindness, and severe mental retardation until their deaths. The brain of the 8-year-old who died at age 30 showed cortical atrophy, neuronal loss, and gliosis, most pronounced in the paracentral and parietooccipital regions. The total mercury level in formalin-fixed, left occipital cortex was 1,974 ng/gm as measured by atomic absorption. Regional brain mercury levels correlated with extent of brain damage. A control patient had 38.5 ng of mercury/gm in the occipital cortex. Systemic organs in the patient and a control subject had comparable mercury levels. In mercury-intoxicated rats, we found that only 5 to 10% of total brain mercury was lost by formalin fixation. Brain inorganic mercury in the patient ranged from 82 to 100%. Since inorganic mercury crosses the blood-brain barrier poorly, biotransformation of methyl to inorganic mercury may have occurred after methylmercury crossed the blood-brain barrier, accounting for its persistence in brain and causing part of the brain damage.

The challenge of racial difference: skills for clinical practice

Just as racial injustice negatively affects the plight of minorities in society, racial tensions impede professional helping. Often, the racially dissimilar social worker and client approach each other with little understanding of each other's social realities and with unfounded assumptions. Unfortunately, professionals find it difficult to acknowledge such differences or their effect on their relationships. Yet the fruitfulness of the helping encounter often depends on the ability to develop and invest in a trusting relationship. This article identifies the societal roots of the stresses associated with cross-racial relationships. Three concerns commonly experienced by clients whose workers are racially different are identified: (1) Is the helper a person of goodwill? (2) Is the helper trained and skilled? (3) Is the help offered valid and meaningful for me and my social reality? Case vignettes are used to illustrate how each concern is typically mishandled. The importance of successfully managing each concern is stressed, and skills for successful management are illustrated.

Effect of atrial natriuretic peptide on vascular permeation in the ovine fetus

To study the effect of atrial natriuretic peptide (ANP) on vascular permeation of albumin in the fetus, ANP (167-600 ng/min) was infused into eight ovine fetuses and saline vehicle was infused into eight twin controls (gestational age 127 +/- 3 d) over a 50-min period. Using two different radiolabeled albumin markers, we determined the tissue to blood isotope ratio (TBIR), an index of albumin permeation, and the albumin clearance. Although ANP had no hemodynamic effect, a marked increase in the hematocrit was observed in ANP-infused fetuses compared with initial values (0.37 +/- 0.04 vs 0.42 +/- 0.04, p < 0.005) but was unchanged in the twin fetuses receiving saline vehicle (0.35 +/- 0.03 versus 0.35 +/- 0.02). TBIR and albumin permeation were increased in combined tissues of ANP-infused fetuses compared with saline controls (TBIR: 1.49 +/- 0.58 versus 1.29 +/- 0.3, p < 0.001; albumin clearance: 1091 +/- 1279 versus 827 +/- 1464 nL/g/min, p < 0.01). In individual tissues, TBIR was significantly increased in skin (2.88 +/- 0.67 versus 1.55 +/- 0.35, p < 0.02), muscle (1.6 +/- 0.27 versus 1.24 +/- 0.26, p < 0.02), adrenal (1.33 +/- 0.10 versus 1.13 +/- 0.15, p < 0.02), bone (1.67 +/- 0.45 versus 1.20 +/- 0.40, p < 0.02), kidney (1.52 +/- 0.25 versus 1.24 +/- 0.26, p < 0.03), and gut (1.69 +/- 0.20 versus 1.39 +/- 0.34, p < 0.03).(ABSTRACT TRUNCATED AT 250 WORDS)

An assessment of practitioner cross-racial treatment experiences

This study sought to determine differences in the cross-racial practice experiences of white and minority social services practitioners. Fifty-three counselors in a Veterans Administration outreach center evaluated various aspects of their cross-racial practice experiences. Both white and minority counselors perceived themselves to work equally well with white clients, but white counselors perceived themselves to be less effective when working with minority clients. The majority of white and minority counselors reported identifying the source of white clients' problems as being internal and that of minority clients' problems as being external. This finding was interpreted as being a possible bias against white clients on the part of both white and minority practitioners. White counselors reported experiencing less client credibility, and minority counselors reported more incidents of racism. Implications for social work are discussed.

Cortical organization in adulthood is modified by neonatal infarct: a case study

PURPOSE

To assess anomalous cortical organization of somatosensory function in a 23-year-old man who had had a neonatal infarct involving the left middle cerebral artery.

MATERIALS AND METHODS

The infarct destroyed the primary and secondary somatosensory areas of the subject's left hemisphere but caused only mild perturbation of somatosensation on the right side of his body. With magnetic source imaging, the authors integrated magnetoencephalographic data with magnetic resonance imaging data to create magnetic source localization images that showed the mapping between brain function and structure.

RESULTS

Electrical stimulation of the right median nerve evoked activity in two nontraditional areas: (a) an intact region of the left inferior temporal gyrus and (b) the ipsilateral right medial parietal cortex.

CONCLUSION

These data suggest that bilateral neural reorganization can be induced by unilateral neonatal damage.

The effect of dietary protein depletion on hepatic 5-fluorouracil metabolism

BACKGROUND

Protein calorie malnutrition, which is highly prevalent in tumor-bearing hosts, increases toxicity to 5-fluorouracil (5-FU), but the mechanisms are unclear. This study investigated the effects of protein depletion on 5-FU in vivo hepatic metabolism using F19-nuclear magnetic resonance spectroscopy (19F-NMRS).

METHODS

Rats received normal (21.5%) or low (2.5%) protein diet for 25 days. 5-FU was injected intraperitoneally, and hepatic fluorine spectra were obtained. Parallel experiments were conducted to determine serum 5-FU pharmacokinetics using high-performance liquid chromatography (HPLC) and to measure hepatic dihydropyrimidine dehydrogenase (DPD) activity.

RESULTS

The mean time of initial detection of fluoro-beta-alanine and the mean duration of the 5-FU signal in the liver were significantly prolonged in the low-protein group. 5-FU clearance and hepatic DPD activity were significantly lower in the low-protein group. Low-protein animals demonstrated increased toxicity, with diarrhea, weight loss, leukopenia (P < 0.001), and an 85% mortality, compared with regular diet animals, who had mild diarrhea and weight loss but no leukopenia and a 12% mortality.

CONCLUSION

Protein depletion results in increased toxicity to 5-FU, which is associated with a significantly decreased rate of hepatic metabolism and clearance of 5-FU and a significant decrease in hepatic DPD activity. 19F-NMRS can noninvasively identify these alterations of 5-FU metabolism in vivo and may serve as a useful guide to determining chemotherapy dosage adjustments to reduce toxicity.