Corticosteroid therapy for the treatment of optic neuritis

Optic neuritis is frequently the first clinical sign of multiple sclerosis (MS). Study results indicate that methylprednisolone pulse therapy reduces the rate of development of MS over a two year period. Patients also experience quicker recovery of vision. This short duration therapy presents immediate and intense nursing care challenges. Coordination of care between three departments at the University of Michigan Medical Center enables many patients to complete IV [intravenous] pulse therapy at home. Although coordination is challenging for providers, ambulatory care and home care benefit patients and their families with potential healthcare cost savings.

Mechanisms of proton-induced stimulation of CGRP release from rat antrum

Mechanisms of acid-evoked CGRP release from gastric afferent nerves were investigated in rat antral mucosal/submucosal tissues. Low pH (pH 4.0, 5.0 and 6.0) stimulated antral CGRP release significantly and dose-dependently from rat antral fragments. Removal of extracellular calcium from the incubation medium resulted in significant inhibition (59%, P < 0.001) of acid (pH 4.0)-stimulated CGRP release. Conotoxin (1 x 10(-7) M), the selective blocker of N-type calcium channels, also significantly inhibited proton (pH 4.0)-induced CGRP release to values that were 74% below net stimulated levels. Neither nifedipine (1 x 10(-6) M), the L-type Ca(2+)-channel antagonist, nor indomethacin (1 x 10(-5) M), inhibitor of prostaglandin synthesis, altered acid-induced CGRP release. In contrast, ruthenium red (1 x 10(-5) M), capsaicin antagonist, almost completely prevented acid (pH 4.0)-stimulated CGRP release. Capsazepine (1 x 10(-4) M), a specific capsaicin receptor antagonist, also completely abolished acid-induced CGRP release. In conclusion, the results of these studies indicate that hydrogen ions are capable of evoking CGRP release from peripheral sensory neurons in rat antral mucosal/submucosal tissues. Proton-evoked CGRP release requires extracellular calcium and involves N-type calcium channels. Furthermore, acid appears to exert a capsaicin-like effect to evoke sensory neuropeptide release that is sensitive to capsazepine and ruthenium red. These data suggest that proton-induced antral CGRP release represents a direct action of hydrogen ions on mucosal/submucosal sensory dendritic nerve endings to effect local release of neuropeptide.

Beta 2-microglobulin, HIV-1 p24 antibody and acid-dissociated HIV-1 p24 antigen levels: predictive markers for vertical transmission of HIV-1 in pregnant Ugandan women

OBJECTIVES

To evaluate the clinical utility of plasma beta 2-microglobulin (beta 2M) levels, acid-dissociated HIV-1 p24 antigen, and HIV-1 p24-antibody titers in predicting HIV-1 vertical transmission in 227 HIV-1-infected Ugandan pregnant women.

DESIGN

Plasma beta 2M levels, acid-dissociated HIV-1 p24-antigen positivity, and HIV-1 p24-antibody titers were determined using commercial enzyme immunoassays (EIA) in a Ugandan cohort of 52 HIV-1-seropositive transmitting mothers, 175 HIV-1-seropositive non-transmitting mothers, and 52 seronegative mothers within 6 weeks prior to delivery.

RESULTS

Transmitter mothers had significantly higher plasma concentrations of beta 2M (1.80 +/- 1.13 mg/l) than non-transmitter seropositive mothers (1.32 +/- 0.81 mg/l; P = 0.0013). Similarly, a significantly higher proportion of transmitter mothers had detectable p24 antigen than non-transmitter mothers [six out of 51 (11.8%) versus six out of 173 (3.5%); P = 0.03]. Compared with the vertical transmission rate of 23% in the seropositive group, the positive predictive values of a beta 2M level > 1.5 mg/l or detectable HIV-1 p24 antigen for vertical transmission were 34 and 50%, respectively. Five of six (83.3%) seropositive mothers with both a beta 2M level > 1.5 mg/l and detectable p24 antigenemia transmitted HIV-1 infection to their infants compared with 25 of 124 (20.2%) seropositive mothers with values below the cut-off values for both tests (P = 0.00249). However, beta 2M was not found to be a significant independent predictor of vertical transmission when analyzed in a multivariate model with p24 antigenemia. There was no significant difference in HIV-1 p24-antibody titers in transmitter mothers versus non-transmitter mothers (P = 0.299).

CONCLUSION

beta 2M levels and acid-dissociated HIV-1 p24-antigen assays may be used to predict which HIV-1-infected pregnant women are at greatest risk for vertical transmission. However, only the p24-antigen test was independently predictive of vertical transmission and its clinical utility is limited.

Combined administration of a gonadotropin-releasing hormone antagonist and testosterone in men induces reversible azoospermia without loss of libido

GnRH antagonists suppress pituitary and gonadal function by competing with endogenous GnRH for binding to receptors on pituitary gonadotrophs. We studied the effects of GnRH antagonist administration to men in a protocol simulating a likely male contraceptive regimen combined with a low dose of testosterone. The GnRH antagonist Nal-Glu was given daily (10 mg, sc) for 20 weeks to eight normal men, and a low dose of testosterone enanthate (25 mg, sc) was given every week. Sperm counts started declining during week 4, and complete azoospermia was reached within 6-12 weeks in six of the eight subjects. Subjects 7 and 8, whose sperm counts and serum gonadotropin levels were not suppressed after 10 weeks, were given 20 mg Nal-Glu starting at week 10. One became azoospermic at week 16, while the other's total sperm counts continued declining and reached a nadir of 1.4 million by week 20. Sperm motility and viability in this subject were completely suppressed after week 14. Sperm counts returned to baseline levels 12-14 weeks after the end of Nal-Glu administration. The mean serum LH level of the first six subjects decreased from 3 +/- 03. U/L at baseline to less than 0.1 U/L until week 20, and then levels returned to baseline. FSH levels similarly decreased from a combined mean of 3.6 +/- 0.9 U/L at baseline to below 0.3 U/L after 4 weeks of Nal-Glu administration. Serum mean testosterone levels between weekly injections of testosterone enanthate ranged from 27.4 +/- 5.9 to 4.8 +/- 1.4 nmol/L, but remained in the hypogonadal range (less than 10 nmol/L) for 4 of the 7 days. None of the subjects, however, complained of decreased libido or potency, as assessed by a questionnaire. No systemic or significant local side-effects were observed, other than a minimal reaction at the injection site. These data suggest that complete sustained azoospermia can be achieved in man, without loss of libido, by chronic administration of a GnRH antagonist plus testosterone.

Intracarotid hydroxyethyl methacrylate solution causing stroke in dogs

Hydroxyethyl methacrylate (HEMA) has been advocated as a polymerizing solution with which to prevent deflation of detachable balloons in interventional neuroradiology. It is pertinent to know if unpolymerized HEMA would have untoward effects if accidentally released into the carotid artery by balloon rupture or deflation. Seven mongrel dogs underwent transfemoral catheterization of the common carotid artery and subsequent injection of HEMA solution in volumes of 1 cc in five dogs, 2 cc in one, and 4 cc in one. Angiography performed at the time of injection revealed evidence of intravascular thrombosis as well as possible spasm. Three surviving animals were sacrificed at 48 hours; the brains were fixed and examined histopathologically. One brain was normal and one was autolyzed and could not be examined. Five of the seven animals had histopathologically documented cerebral infarctions of varying size. No foreign substance was seen within the blood vessels to suggest intravascular polymerization. The animals injected with 2 or 4 cc HEMA solution did not survive 48 hours. Literature review reveals little documentation of the toxicology of intravascular HEMA. With its increasing popularity as a compound for polymerization in detachable balloons introduced into the brain, further investigations are warranted to understand the physical properties of the compound and potential risks of its use.

Immunocytochemical analysis of embryonic compartmentation with a monoclonal antibody against a cytokeratin-related antigen

Mab 113F4, a monoclonal antibody recognizing an antigen in the outer synaptic layer of the chick neural retina, also recognizes an antigen appearing in all three germ layers of the gastrulating chick embryo. However, as neurulation proceeds, the antigen is down-regulated in three distinct patterns. First, the antigen is lost specifically from those trunk ectodermal cells destined to form the neural plate and, later, the neural tube. It remains absent from any neural derivative until day 13 when it appears in the outer synaptic layer of the neural retina, coincident with synaptogenesis in this region. Second, the entirety of the head ectoderm loses this antigen as the head lifts off the blastoderm. This down-regulation is followed later by a similar loss of antigen expression in the trunk ectoderm. Third, expression in the mesoderm becomes limited to the lateral plate and extraembryonic epithelia. Endodermal derivatives continue to express the antigen throughout development. Antigen 113F4 is localized within the cytoplasm and is organized in a fibrillar pattern. The intracellular localization of this antigen and its characteristic spatio-temporal tissue distribution are consistent with the antigen being a cytokeratin or cytokeratin-related antigen. The changes in tissue distribution suggest a possible role in tissue modelling in response to inductive interactions during development.

Reversible middle cerebral artery embolization in dogs without intracranial surgery

Using dogs, we developed an intravascular model for reversible middle cerebral artery occlusion that does not involve intracranial surgery or enucleation. Using silicone plastic plugs with a suture embedded within them, we embolized the middle cerebral artery in 19 dogs via the cervical carotid artery. The free end of the suture remained accessible in the neck, and after variable dwell times traction was placed on the suture and the plug was withdrawn. Placement of the plug in the middle cerebral artery produced ischemia in the basal ganglia. The degree and distribution of cortical ischemia were variable as evidence by the pathologically documented scattered nature of infarcts that resulted when the plug was left permanently in the middle cerebral artery and when it was removed after 1 or 2 hours. Angiography demonstrated occlusion of the middle cerebral artery with the plug in place as well as reperfusion when the plug was withdrawn. This modification of a previously described model of middle cerebral artery occlusion provides an opportunity to study structural, physiologic, and biochemical events occurring in acutely hypoperfused cerebral tissue as well as critical changes leading to irreversible injury without the disadvantages of surgical manipulation required by all previous models of reversible cerebral ischemia.

St Paul and temporal lobe epilepsy

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