Fite stain positivity in Rhodococcus equi: yet another acid-fast organism in respiratory cytology--a case report

Rhodococcus equi is an aerobic Gram-positive and acid-fast coccobacillus that may cause cavitary pneumonia in immunocompromised hosts such as HIV-infected patients. Numerous Grocott's methenamine silver (GMS)-positive organisms were initially noted on the direct smear; a minor number of acid-fast organisms were seen in the Thin-Prep slide. Since the abundant mucous material with the attached organisms seen in conventional smears may be lost in liquid-based preparations, more sensitive stains such as Fite, as well as a more diligent search for organisms, is needed. This case illustrates the importance of careful selection and evaluation of special stains in sputum specimens.

Effect of chronic treatment with the GABA transaminase inhibitors gamma-vinyl GABA and ethanolamine O-sulphate on the in vitro GABA release from rat hippocampus

1. The effects of 2, 8 and 21 day oral treatment with the specific gamma-aminobutyric acid transaminase (GABA-T) inhibitors gamma-vinyl GABA (GVG) and ethanolamine O-sulphate (EOS) on brain GABA levels, GABA-T activity, and basal and stimulated GABA release from rat cross-chopped brain hippocampal slices was investigated. 2. Treatment with GABA-T inhibitors lead to a reduction in brain GABA-T activity by 65-80% compared with control values, with a concomitant increase in brain GABA content of 40-100%. 3. Basal hippocampal GABA release was increased to 250-450% of control levels following inhibition of GABA-T activity. No Ca2+ dependence was observed in either control or treated tissues. 4. GVG and EOS administration led to a significant elevation in the potassium stimulated release of GABA from cross-chopped hippocampal slices compared with that of controls. Although stimulated GABA release from control tissues was decreased in the presence of a low Ca2+ medium, GVG and EOS treatment abolished this Ca2+ dependency. 5. GABA compartmentalization, Na+ and Cl- coupled GABA uptake carriers and glial release may provide explanations for the loss of the Ca2+ dependency of stimulated GABA release observed following GVG and EOS treatment. 6. Administration of GABA-T inhibitors led to increases in both basal and stimulated hippocampal GABA release. However, it is not clear which is the most important factor in the anticonvulsant activity of these drugs, the increased GABA content 'leaking' out of neurones and glia leading to widespread inhibition, or the increase in stimulated GABA release which may occur following depolarization caused by an epileptic discharge.

Extracellular levels of glutamate and aspartate in the entopeduncular nucleus of the rat determined by microdialysis: regulation by striatal dopamine D2 receptors via the indirect striatal output pathway?

This study used intracerebral microdialysis to monitor the outputs of excitatory amino acids in the entopeduncular nucleus (EPN) of conscious or halothane-anaesthetized rats, in an attempt to obtain direct biochemical evidence for the theory that neuronal inputs to the EPN by the indirect striatal output pathway are glutamatergic and regulated primarily by dopamine D2 receptors in the striatum. In dopamine-intact animals, both glutamate and asparate were readily detectable in EPN dialysates. Recoveries of both amino acids were increased bilaterally by local perfusion with veratridine (100 microM, given under halothane anaesthesia), pretreatment with reserpine (4 mg/kg, i.p., 24 h beforehand), unilateral pretreatment of the medial forebrain bundle with 6-OHDA (8 microg/4 microl), and by the systemic (1 mg/kg, i.p.) or bilateral intrastriatal (7 microg/0.5 microl under halothane anaesthesia) administration of the dopamine D2 receptor antagonist haloperidol, but not raclopride (2 mg/kg, i.p.). The dopamine D1 receptor antagonist SCH 23390 was ineffective both systemically (0.25 mg/kg, i.p.) and intrastriatally (0.125 microg/0.5 microl/side), as also were control intrastriatal injections of saline (0.5 microl/side). By contrast, the dopamine D2/3 receptor agonist quinpirole (4 mg/kg, i.p.) lowered the outputs of glutamate and aspartate in the EPN of reserpine-treated and normal individuals, whilst the dopamine D1 receptor agonist SKF 38393 (30 mg/kg, i.p.) was inactive; however, both drugs caused behavioural arousal. The dopamine D2/3 receptor agonist RU 24213 reversed reserpine-induced akinesia, yet paradoxically increased glutamate (not aspartate) output in the EPN still further. The combination of benserazide (30 mg/kg, i.p.) and L-DOPA (50 mg/kg, i.p.) evoked intense contraversive circling in unilaterally 6-OHDA-lesioned rats, together with a drop in EPN glutamate (but not aspartate) output in the intact but not lesioned hemisphere. These results offer biochemical support for the hypothesis that excitatory neurones innervating the EPN via the indirect striatal output pathway, may utilise glutamate and/or aspartate as their neurotransmitter. They further endorse the view that the EPN receives information from striatal D2 and not D1 receptors via excitatory synapses, which become hyperactive following dopamine depletion or inactivation, and which are subject to control by the contralateral as well as by the ipsilateral hemisphere. The results obtained with RU 24213 and L-DOPA, however, indicate that dopaminergic behaviours can also occur independently of glutamate or aspartate release in the EPN.

AMPA receptors modulate extracellular 5-hydroxytryptamine concentration and metabolism in rat striatum in vivo

We have investigated the effects of infusing the excitatory amino acid agonist alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) on extracellular levels of 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) in rat striatum using in vivo microdialysis. AMPA (50-500 microM) caused a concentration-dependent increase in extracellular 5-HT, while having the converse effect on 5-HIAA. At the highest agonist dose the decrease in dialysate 5-HIAA was followed by a significant increase in this metabolite. Two hundred micromolar 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), a competitive non-NMDA glutamate receptor antagonist, reversed the effects of a 100 microM AMPA on dialysate 5-HT and 5-HIAA. Co-infusion of AMPA with tetrodotoxin (TTX) abolished the effects of 100 microM AMPA, but only partially reversed the effect of 500 microM AMPA on 5-HT release. We have also investigated whether AMPA receptor desensitization, a well documented event, plays a role in AMPA receptor modulation of striatal 5-HT release. Diazoxide (500 microM), a drug which prevents AMPA receptor desensitization, failed to augment the effect of 100 microM AMPA on 5-HT release. Diazoxide alone significantly decreased 5-HT release, as did the drug cromakalim (100 microM), probably as a result of their common action as activators of ATP-dependent K+ channels. It is concluded that AMPA receptors play a role in regulating both 5-HT release and metabolism in rat striatum. However, AMPA receptor desensitization does not appear to play a role in this process in this structure.

Effects of chronic oral treatment with GABA-transaminase inhibitors on the GABA system in brain, liver, kidney, and plasma of the rat

The inhibitory neurotransmitter gamma-aminobutyric acid (GABA) is not solely located in the CNS, it and the enzymes responsible for its synthesis (glutamic acid decarboxylase, GAD, EC 4.1.1.15) and catabolism (GABA-transaminase, GABA-T, EC 2.6.1.19) are also present in non-neuronal organs. Following 2, 8 and 21 day oral administration of ethanolamine-O-sulphate (EOS) and gamma-vinyl GABA (GVG), two irreversible inhibitors of GABA-T, the GABA content and activities of GAD and GABA-T in rat brain, liver and kidney, and the GABA content of plasma were determined: GABA-T activity was significantly decreased (over 80%) in liver, brain and kidney, although there was 2-3 times the residual activity left in the brain compared with the peripheral organs. GABA content was subsequently significantly elevated in the liver (300-1500%), plasma (200-300%) and brain (200-300%), although, surprisingly, the kidney GABA content was reduced (by 60-70%) compared with control. GAD activity was decreased following 8 day treatment in liver and brain. Kidney GAD was reduced at all time points. These two compounds are anticonvulsant, GVG is used clinically for the treatment of epilepsy but it seems that these drugs have significant peripheral effects.

Effects of preoperative chemotherapy on the morphology of resectable breast carcinoma

We examined pathologic specimens from 43 patients with Stage T1-T3 lesions who were treated preoperatively with four cycles of doxorubicin/cyclophosphamide, followed by segmentectomy/mastectomy and axillary node dissection (the National Surgical Adjuvant Breast and Bowel Project B-18 protocol). Specimens from 46 patients treated post-operatively with the same regimen served as histologic controls. The initial diagnosis was made by core needle biopsy (28%) or by fine-needle aspiration (72%). Six changes were noted in 36 patients (84%), with complete regression in 10, but histologic evidence of regression and characteristic cytologic changes occurred in only one-half of the 43 patients, and there was poor correlation between histologic regression and clinical response; (2) an increased nuclear grade occurred in 32% of the cases; (3) unusually prominent intraductal and/or intralymphatic tumor was observed in 40%; (4) histologic evidence of tumor regression in axillary lymph nodes was noted in nine cases; (5) regressive changes also occurred in non-neoplastic breast tissue and in lymphoid populations of lymph nodes; and (6) difficulty was noted in evaluating residual atypical intraductal proliferations. These findings add a quantitative dimension to previously published descriptions and emphasize the need for pathologic staging in these patients. In addition, they provide histopathologic evidence of downstaging in axillary lymph nodes and of relative treatment resistance by intraductal and intralymphatic tumor.

Apocrine metaplasia in gynecomastia by fine needle aspiration as a possible indicator of anabolic steroid use. A report of two cases

BACKGROUND

The fine needle aspiration finding of apocrine metaplasia in association with the usual cytologic findings of gynecomastia is distinctly unusual. Previous reports do not mention any historical clinical association.

CASES

Two otherwise healthy adult males presented for fine needle aspiration (FNA) of new-onset breast masses. Both showed apocrine metaplasia associated with the typical clinical and cytologic features of gynecomastia on FNA. Additional questioning revealed that both patients reported recent anabolic steroid use as part of their body-building routines.

CONCLUSION

The fine needle aspiration finding of apocrine metaplasia in association with the usual cytologic and clinical findings of gynecomastia in otherwise healthy adult males without a medication history may be an indicator of illicit anabolic steroid use. Anabolic steroid use often has serious consequences, so its possibility should prompt further evaluation by the patient's clinician.

Tetanus toxin-induced effects on extracellular amino acid levels in rat hippocampus: an in vivo microdialysis study

Tetanus toxin is a potent neurotoxin that is widely considered to produce its effect through impairment of inhibitory neurotransmission. We report the effect of a single unilateral intrahippocampal injection of tetanus toxin on extracellular levels of neuroactive amino acids in freely moving rats, at times ranging between 1 and 7 days posttreatment. Tetanus toxin treatment did not alter extracellular levels of aspartate, glutamate, and taurine at any time during the study. However, although extracellular GABA levels were unaffected by toxin injection 1, 2, and 3 days after treatment, they were reduced (45 +/- 8% of contralateral vehicle-injected level) at day 7. Challenge with a high K+ concentration, 7 days after treatment, produced elevations in extracellular levels of taurine and GABA in both vehicle- and toxin-injected hippocampi, with evoked levels of GABA being lower in the toxin-treated side (39 +/- 16% of contralateral vehicle-injected level). Aspartate and glutamate levels were not increased by high-K+ infusion. These findings are discussed in relation to the possible role that an imbalance in excitatory/inhibitory tone may play in the production of tetanus toxin-induced neurodegeneration.

Evidence for release of glutamic acid, aspartic acid and substance P but not gamma-aminobutyric acid from primary afferent fibres in rat spinal cord

In vitro superfusion release experiments and autoradiography were carried out on spinal cords of neonatally capsaicin-treated rats. Electrical and chemical stimulations significantly increased the release of aspartate, glutamate and gamma-aminobutyric acid (GABA) from hemisected dorsal horn slices of vehicle-treated animals. In capsaicin-treated rats, the evoked release of aspartate, glutamate and substance P but not GABA, were significantly lower. Capsaicin (1 microM) stimulated the release of aspartate and glutamate, as reported for substance P, in control slices but this effect was not as apparent in tissues from capsaicin-treated rats. Evoked GABA release was not affected in either case. alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), kainate, dizocilpine and GABAB binding sites were highly localised in the substantia gelatinosa. Capsaicin treatment did not affect the affinity of the binding sites in all four cases but significantly reduced the density of kainate, dizocilpine and GABAB binding sites. The data suggest that capsaicin-sensitive primary afferent fibres release aspartate, glutamate and Substance P following high-intensity stimulations and that this release might be modulated by presynaptic glutamate and GABAB receptors present on these terminals.

NMDA receptor antagonists increase the release of dopamine in the substantia nigra of reserpine-treated rats

Microdialysis of the substantia nigra pars reticulata in freely moving rats disclosed a steady release of dopamine and its metabolites which was greatly reduced after reserpine (4 mg/kg s.c.) and alpha-methyl-p-tyrosine (200 mg/kg i.p.) pretreatments. Local infusion of high K+ (100 mM) or L-3,4-dihydroxyphenylalanine (L-DOPA, 10 microM) significantly increased dialysate levels of dopamine and 3,4-dihydroxyphenylacetic acid (DOPAC), but not homovanillic acid (HVA) in this model. Intranigral application of the non-competitive NMDA receptor antagonist dizocilpine (150 nM), or the competitive NMDA receptor antagonist R-DL-(E)-2-amino-4-methyl-5-phosphono-3-pentanoate (CGP 40116, 10 microM), via the dialysis probe, did not affect the release of dopamine or its metabolites in intact rats, but further suppressed these releases in reserpine plus alpha-methyl-p-tyrosine-treated animals. When the same amounts of dizocilpine or CGP 40116 were coinfused with L-DOPA, however, they potentiated the recovery of dopamine 12-24 times, and of DOPAC 5-10 times (but not HVA), as well as producing detectable behavioural arousal. The facilitation of dopamine formation from L-DOPA by NMDA receptor antagonists in the substantia nigra pars reticulata could explain the enhancement of L-DOPA's antiparkinsonian activity by these compounds in behavioural experiments.

Effect of lamotrigine on the electrically-evoked release of endogenous amino acids from slices of dorsal horn of the rat spinal cord

The novel anti-epileptic, lamotrigine (LTG) has been shown to exhibit antinociceptive effects in the rat. In the present study, the effect of LTG on the electrically-evoked release of endogenous amino acids from rat isolated spinal dorsal horn slices with intact dorsal roots has been examined and compared with those of morphine in the same preparation. LTG (0.1-300 microM) inhibited the release of aspartate, glutamate and GABA in a concentration-dependent manner. The lowest concentrations of morphine (0.001-0.01 microM) enhanced the stimulated release of aspartate and glutamate while the higher concentrations inhibited their release. Stimulated GABA release was reduced in a concentration-dependent manner. The anticonvulsant was more potent at inhibiting the release of glutamate (IC50 = 20 microM) than that of GABA (IC50 = 44 microM) supporting the previous suggestion that lamotrigine is a selective inhibitor of glutamate release. This suggests that the reduction in glutamate release could be one of the mechanisms by which lamotrigine exerts its antinociceptive effect.

Diagnosis of Epstein-Barr virus associated nasopharyngeal carcinoma using fine-needle aspiration biopsy and molecular diagnostics

Molecular technology is being utilized increasingly for diagnostic purposes by practicing pathologists. Techniques such as Southern blot, in situ hybridization, and polymerase chain reaction have recently been introduced to the clinical laboratory setting. We describe a case of nasopharyngeal carcinoma that highlights the potential utility of DNA technology to secure an accurate diagnosis of a fine-needle aspiration biopsy. In this patient, cytologic examination of a cervical lymph node aspirate strongly suggested the possibility of a nasopharyngeal carcinoma. Needle aspirate material was submitted for molecular genetic detection of the Epstein-Barr virus (EBV) genome. Nine micrograms of DNA were isolated, and the presence of clonal EBV DNA was detected by the Southern blot technique. The presence of clonal EBV supported the cytologic diagnosis of nasopharyngeal carcinoma. Subsequent biopsy of a nasopharyngeal mass revealed undifferentiated carcinoma, and in situ hybridization revealed that EBV was restricted to the malignant epithelial cells. This case illustrates how molecular technology can provide new information that is useful in diagnostic cytopathology.

alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionate receptors modulate dopamine release in rat hippocampus and striatum

The effects of infusing the glutamate receptor agonist alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) on the release of dopamine (DA) has been studied in rat hippocampus and striatum in vivo. In hippocampus, AMPA (1-10 microM) produced a dose related increase in dialysate DA, but at 100 microM AMPA a sustained decrease in extracellular DA was observed. However, when samples were collected at 5-min intervals 100 microM AMPA infusion revealed a brief increase in hippocampal dialysate DA. Infusion of 100 microM AMPA and 500 microM diazoxide, which blocks AMPA receptor desensitization, led to a marked increase in extracellular DA, as did diazoxide alone, although to a lesser extent. The AMPA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3,-dione (CNQX; 200 microM) reversed the effect of AMPA and/or diazoxide infusion on dialysate DA and when infused alone, CNQX also decreased hippocampal dialysate DA. AMPA (50-500 microM) increased striatal DA release. The effect of AMPA on extracellular DA was reversed by CNQX (200 microM). Diazoxide infusion caused a decrease in striatal DA release, and this was not affected by CNQX. These data suggest that hippocampal, but not striatal AMPA receptor desensitization may play a role in regulating DA release.

Impulse-dependent and tetrodotoxin-sensitive release of GABA in the rat's substantia nigra measured by microdialysis

gamma-Aminobutyric acid (GABA) release in the rat substantia nigra pars reticulata (SNR) was studied by microdialysis coupled with high-performance liquid chromatography and fluorimetric detection. Electrical stimulation of striatonigral axons in the internal capsule (IC) increased nigral GABA release in conscious and halothane-anaesthetized rats. This was prevented by intranigral infusion of tetrodotoxin (TTX) while basal GABA release was unaffected. Calcium-free, cobalt-containing (2 mM CoCl2) artificial cerebrospinal fluid reduced basal GABA overflow but not that evoked with high K+ (100 mM). Extracellular levels of glutamate (GLU) and taurine (TAU) were not modified by IC stimulation, TTX or 0 Ca2+ although high K+ promoted GABA and TAU release but not that of GLU. These data demonstrate an impulse-and sodium-dependent release of GABA from nigral afferent neurones which contribute little to the extracellular concentration of GABA under steady-state conditions.

The effect of chronic treatment with the GABA transaminase inhibitors gamma-vinyl-GABA and ethanolamine-O-sulphate on the in vivo release of GABA from rat hippocampus

The effects of chronic treatment with the specific, mechanism-based, irreversible inhibitors of 4-aminobutyrate aminotransferase (EC 2.6.1.19; GABA transaminase), ethanolamine O-sulphate (EOS), and 4-aminohexenoate [vigabatrin; gamma-vinyl-GABA (GVG)] on the extracellular concentrations of GABA in the hippocampus have been studied using in vivo microdialysis in conscious animals. Oral dosing [3 mg/ml of drinking water, giving doses of GVG of 194 +/- 38 mg/kg/day and of EOS of 303 +/- 42 mg/kg/day (mean +/- SD)] was followed by microdialysis at 2, 8, and 21 days. The basal outflow of GABA (in the range of approximately 1-2 pmol/30 microliters/30-min sample) after 2 and 8 days of treatment was not significantly different from that in control animals, but the 21-day treatment gave significant rises in the extracellular GABA concentration (up to approximately 6-8 pmol/30 microliters/30-min sample). Both inhibitors gave similar results. Depolarisation with 100 mM K+ gave large increases in GABA release in control (approximately 20-60 pmol/30 microliters/30-min sample) and treated animals. The 8- and 21-day-treated animals showed significant increases in the stimulated release compared with control animals (approximately 80-100 pmol/30 microliters/30-min sample). Excluding Ca2+ had no significant effect on either basal or stimulated release. The significant increases in K(+)-evoked release of GABA show that the increased intracellular pool of GABA is available for release, and this may be related to the anticonvulsant action of these compounds.

Minimally invasive Paget's disease of the vulva with extensive lymph node metastases

Optimal treatment for intraepithelial and invasive Paget's disease of the vulva has been previously evaluated. The treatment of disease with minimal invasion (< or = 1 mm) represents an even greater dilemma. We report a case of Paget's disease of the vulva with 1-mm depth of invasion presenting with extensive inguinofemoral lymph node metastases documented by fine-needle aspiration biopsy.

Effect of isonicotinic acid hydrazide on extracellular amino acids and convulsions in the rat: reversal of neurochemical and behavioural deficits by sodium valproate

We have studied the effect of isonicotinic acid hydrazide (INH), a convulsant agent, on the extracellular levels of amino acids in the hippocampus, and the effect of sodium valproate (VPA) administration in INH-treated rats. INH (250 mg/kg) caused a rapid and sustained decrease in basal levels of GABA, and during this period convulsions of increasing severity were observed. Basal levels of glutamine, taurine, aspartate, and glutamate were unchanged by INH. When VPA was coadministered with INH, basal GABA levels were increased and no convulsions were observed. When transmitter release was evoked using 100 mM K+, the increase in dialysate GABA observed in INH-treated animals was less than that seen in controls and convulsions increased in frequency. K(+)-evoked release of glutamate and aspartate tended to be higher following INH treatment, and in the case of aspartate, this increase was significant. VPA reversed the changes in evoked release of glutamate and aspartate, and release of GABA was considerably greater than that seen in control or INH-treated rats. No drug effect on evoked changes in taurine or glutamine level was seen. These are the first data to show decreased extracellular GABA in conjunction with convulsions in freely moving animals in vivo.

Tonic desensitization of hippocampal alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors regulates 5-hydroxytryptamine release in vivo

Strong evidence implicates glutamate as an excitatory neurotransmitter in the central nervous system. In the present study we have investigated the effects of different concentrations of the excitatory amino acid agonist alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid on release of 5-hydroxytryptamine in rat hippocampus using in vivo microdialysis. Infusion of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid at 1 microM led to an increase in dialysate 5-hydroxytryptamine. In contrast 100 microM alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid decreased extracellular 5-hydroxytryptamine, collected in 30 min samples, and this decrease was sustained for several hours. alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor desensitization is well documented in vitro, and is reversed by the drug diazoxide. We therefore studied the possibility that this was occurring in hippocampus in vivo. Collection of dialysates at 5 min time intervals revealed a brief increase in dialysate 5-hydroxytryptamine in response to 100 microM alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, although basal level of 5-hydroxytryptamine was below the level of detection. When 100 microM agonist was co-infused with 500 microM diazoxide, a substantial and prolonged increase in dialysate 5-hydroxytryptamine was seen. Diazoxide alone was observed to cause an increase in extracellular 5-hydroxytryptamine. Diazoxide is known to active ATP-dependent K+ channels, however, cromakalim (100 microM), an activator of ATP-dependent K+ channels, reduced hippocampal 5-hydroxytryptamine release, suggesting that the effect of diazoxide is not the result of such an action.(ABSTRACT TRUNCATED AT 250 WORDS)

Human alveolar macrophage-56 and carcinoembryonic antigen monoclonal antibodies in the differential diagnosis between primary ovarian and metastatic gastrointestinal carcinomas

The immunohistochemical expression and localization of monoclonal antibodies to carcinoembryonic antigen (CEA) and human alveolar macrophage (HAM-56) were evaluated in primary ovarian and metastatic gastrointestinal (GI) carcinomas. Immunohistochemistry was performed using an avidin-biotin-peroxidase complex method with capillary gap technology on formalin-fixed, paraffin-embedded tissues from 41 primary ovarian epithelial neoplasms, 17 metastatic gastrointestinal malignancies, and 10 tumors of uncertain primary origin. Overall, immunostaining for HAM-56 was positive in 35 (85%) ovarian epithelial neoplasms compared with only two (12%) gastrointestinal cancers. Carcinoembryonic antigen was positive in 16 (39%) ovarian versus 13 (76%) GI tumors. Of the primary ovarian neoplasms, 22 were positive for HAM-56 only, 13 were positive for both HAM-56 and CEA, three were positive for CEA only (all mucinous neoplasms), and three were negative for both. Of the primary GI neoplasms, 12 were positive for CEA only (including all eight colon cancers), one was positive for both HAM-56 and CEA, one was positive for HAM-56 only, and three were negative for both. Of the 10 neoplasms of unknown origin at initial presentation, six were positive for HAM-56 only, three were positive for CEA only, none was positive for both HAM-56 and CEA, and one was negative for both. Only three of these 10 neoplasms remained of indeterminate origin after pathological review and clinical follow-up. When positive, CEA was usually strong and generalized in GI cancers but weak and focal in ovarian neoplasms. The HAM-56 positivity in ovarian neoplasms was typically focal and largely limited to areas with glandular or papillary differentiation with apical linear accentuation. We conclude that an immunohistochemical panel using both HAM-56 (Enzo Diagnostics, Syosset, NY) and CEA monoclonal antibodies is helpful in differentiating primary ovarian neoplasms from metastatic gastrointestinal malignancies, and in evaluating metastatic adenocarcinoma of unknown primary site.

N-methyl-D-aspartate receptors modulate extracellular 5-hydroxytryptamine concentration in rat hippocampus and striatum in vivo

The effects of infusing N-methyl-D-aspartate (NMDA) and the specific NMDA receptor antagonist D-2-amino-5-phosphonopropionic acid (D-AP5) into rat hippocampus and striatum on extracellular 5-hydroxytryptamine (5-HT) and its metabolite 5-hydroxy-indoleacetic acid (5-HIAA) were studied using intracerebral microdialysis. In striatum, NMDA (1-100 microM) caused a concentration-dependent increase in 5-HT. D-AP5 (10 microM) infusion caused increased extracellular 5-HT. When the two drugs were co-infused, no effect on extracellular 5-HT was seen. D-AP5 alone was found to cause a delayed but sustained increase in dialysate 5-HIAA. In hippocampus, NMDA infusion caused a dose-dependent decrease in extracellular 5-HT while D-AP5 produced a transitory increase in 5-HT level. NMDA caused a decrease in dialysate 5-HIAA. In striatum, the effect of 10 microM NMDA infusion was abolished by co-infusion with tetrodotoxin (TTX; 1 microM). In hippocampus, 1 microM TTX caused a slight but non-significant augmentation of the effect of 10 microM NMDA alone. These data indicate that NMDA receptors mediate control over 5-HT release and metabolism in different brain regions and may in part explain the behavioural effects of non-competitive NMDA receptor antagonists.

N-methyl-d-aspartate receptors modulate extracellular dopamine concentration and metabolism in rat hippocampus and striatum in vivo

The effects of infusing N-methyl-D-aspartate (NMDA), and the specific NMDA receptor antagonist D-2-amino-5-phosphono-propionic acid (D-AP5) into rat hippocampus and striatum on extracellular dopamine (DA) and its metabolites dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) were studied using intracerebral microdialysis. In striatum NMDA increased DA extracellularly in a concentration-dependent manner. Against a 10 microM concentration of NMDA the increase in striatal DA was opposed by D-AP5 (10 microM in all experiments), which when infused alone significantly reduced DA concentration. Infusion of NMDA altered DOPAC level in a complex manner, with 10 microM concentration causing a significant increase 2 h after infusion, while 100 microM NMDA caused a transient decrease in the metabolite. None of treatments altered striatal dialysate HVA. In hippocampus NMDA infusion decreased dialysate DA in a concentration-dependent manner, and the decrease caused by 10 microM NMDA was reversed by D-AP5. When given alone the antagonist was without effect. NMDA infusion elevated hippocampal dialysate DOPAC and HVA, while HVA was decreased following D-AP5 infusion. These data indicate that DA release is regionally controlled by excitatory amino acids, but in differential manner.

Regional effects of sodium valproate on extracellular concentrations of 5-hydroxytryptamine, dopamine, and their metabolites in the rat brain: an in vivo microdialysis study

The effects of sodium valproate (VPA; 100, 200, and 400 mg/kg, i.p.) on ventral hippocampal and anterior caudate putamen extracellular levels of dopamine (DA) and 5-hydroxytryptamine (5-HT) were examined using in vivo microdialysis. VPA induced dose-related increases in dialysate DA, 3,4-dihydroxyphenylacetic acid, and 5-HT in the ventral hippocampus. Anterior caudate putamen dialysate 5-HT was also dose dependently elevated by the drug, whereas DA levels tended to decrease with increasing VPA dose. In contrast, VPA (200, 400, and 800 mg/kg, i.p.) produced no significant elevation of DA in posterior caudate putamen dialysates, although 5-HT levels were significantly elevated at the 400- and 800-mg/kg doses. In all three regions studied, dialysate concentrations of 5-hydroxyindoleacetic acid and homovanillic acid remained at basal levels following VPA treatments. The results are discussed with regard to the possible anticonvulsant mode of action of VPA.

The effect of sodium valproate on extracellular GABA and other amino acids in the rat ventral hippocampus: an in vivo microdialysis study

We report the effects of i.p. administration of sodium valproate (VPA) on extracellular concentrations of various amino acids in the rat ventral hippocampus studied using in vivo microdialysis, followed by HPLC with fluorometric detection. At the doses used (100, 200 and 400 mg/kg), VPA had no effect on extracellular aspartate, glutamine and taurine, whilst inducing a small, but not statistically significant increase in glutamate at 200 and 400 mg/kg. In contrast, VPA administration produced a biphasic effect on extracellular GABA levels which was dependent on the dose used. At 100 mg/kg, VPA reduced GABA concentrations by 50% when compared to basal. 200 mg/kg VPA had virtually no effect, whilst 400 mg/kg VPA raised extracellular GABA levels to 200% of basal. The results are discussed in relation to the known pharmacological and anticonvulsant actions of VPA.

Regional effects of MK-801 on dopamine and its metabolites studied by in vivo microdialysis

The non-competitive N-methyl-D-aspartate receptor antagonist MK-801 was observed to have regionally specific effects on the extracellular concentration of dopamine and its metabolites. In rat anterior striatum, MK-801 transiently decreased extracellular dopamine, in spite of inducing intense circling behaviour which is generally associated with an increase in this neurotransmitter. In contrast, hippocampal extracellular dopamine was increased in a dose-related manner by MK-801. The possible significance of these data is discussed in relation to some of the known behavioural actions of MK-801.

MK-801 Increases Extracellular 5-Hydroxytryptamine in Rat Hippocampus and Striatum In Vivo

The effect of MK-801 (0.25 or 0.5 mg/kg) on the extracellular concentration of 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) in rat hippocampus and striatum was studied using intracerebral dialysis. The dialysate 5-HT concentration was dose-dependently increased by MK-801 in both regions. In the hippocampus, at the higher drug dose a slow increase in the 5-HIAA level was observed, and this became significant 3 h after treatment. In contrast to this, the extracellular 5-HIAA content in the striatum was significantly decreased 150 min after administration of both doses of MK-801. The data are discussed in the light of the known behavioural effects of MK-801 and possible N-methyl-D-aspartic acid receptor regulation of 5-HT release.

Putative Neurotoxicity of SKF 38393 and Other D1Dopaminergic Drugs Investigated in Rat Striatum

The recently alleged neurotoxicity of the D1 receptor agonist, SKF 38393, was investigated in rat striatum by measuring the enzymes acetylcholinesterase (AChE) and glutamate decarboxylase (GAD). First, unilateral intrastriatal microinjection of the excitotoxin kainic acid (2 micrograms in 1 microliter) was shown to evoke vigorous contraversive circling, followed 1 or 2 weeks later by profound decreases in striatal AChE (24 and 54%), GAD (51 and 75%), and protein (36 and 47%), as well as loss of GAD (45% at 2 weeks) in the ipsilateral substantia nigra. Similar striatal treatments with SKF 38393 (30 micrograms in 0.5-1 microliter), the related benzazepines SKF 82526 (D1 agonist, 30 micrograms in 1 microliter) and SCH 23390 (D1 antagonist, 5 micrograms in 1 microliter), or the phenanthridine D1 agonist CY 208-243 (5 micrograms in 1 microliter) failed to affect the rats' behaviour or their striatal levels of AChE, GAD, and protein. Intrastriatal SKF 38393 (30 micrograms in 0.5 microliter) also had no influence on these enzymes in the substantia nigra. It is concluded that none of the D1 dopaminergic compounds examined here was neurotoxic toward the many different cell groups that contain AChE and/or GAD in the striatum.

The effect of valproic acid on 5-hydroxytryptamine and 5-hydroxyindoleacetic acid concentration in hippocampal dialysates in vivo

The effect of valproic acid (100, 200 and 400 mg/kg i.p.) on extracellular 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) has been studied using intracerebral microdialysis of the ventral hippocampus. Valproate caused a dose-dependent increase in dialysate 5-HT, but in contrast no effect on 5-HIAA level was observed. These findings are considered with regard to a possible role of 5-HT in mediating the anticonvulsant action of valproate.

Fetal death from chlamydial infection across intact amniotic membranes

We report a case of a fetal death at 34 weeks' gestation with intact membranes. An autopsy confirmed intrauterine pneumonia as a result of Chlamydia trachomatis. Staining of the lung tissue with a direct fluorescein-conjugated Chlamydia-specific monoclonal antibody assay revealed a pattern typical of a Chlamydia trachomatis infection. This case supports the thesis that Chlamydia crosses fetal membranes and produces disease.

Micro-vacuolation in rat brains after long term administration of GABA-transaminase inhibitors. Comparison of effects of ethanolamine-O-sulphate and vigabatrin

Two "suicide" inhibitors of GABA-aminotransferase which are known to raise the concentration of GABA in vivo and to have anti-convulsant properties, have been compared for the extent to which they produce micro-vacuoles in the brains of rats. The compounds gamma-vinyl-GABA (Vigabatrin) and ethanolamine-O-sulphate were administered orally for six months to rats at doses that produced the same increase in brain GABA levels. Micro-vacuolation was found to be present in the brains of animals treated with either compound but to be more severe in those treated with Vigabatrin. A quantitative assessment using computerised image analysis revealed that both the number of vacuoles, and the area occupied by them, was twice as high in the Vigabatrin treated animals as in those treated with ethanolamine-O-sulphate. This quantitative difference could be seen to be due to the fact that in the Vigabatrin treated animals the vacuoles extended into the white matter tracts between the cerebellar folia whereas in those animals treated with ethanolamine-O-sulphate it was confined to the roof nucleus.

Purification and properties of rabbit brain and liver 4-aminobutyrate aminotransferases isolated by monoclonal-antibody immunoadsorbent chromatography

The use of a monoclonal-antibody immunoaffinity column for the rapid isolation of 4-aminobutyrate aminotransferases (EC 2.6.1.19) from rabbit brain and liver is described. Homogeneous enzyme protein is eluted from the immunoadsorbent with 100mM-citrate buffer, pH5, and remains stable at 4 degrees C for several days. One such column (bed volume 8 ml) has been used 40 times in a 9-month period to isolate 10-15 units of enzyme activity (specific activity approx. 3.5-7.5 units/mg) per extraction. Kinetic and spectral analysis of the enzymes from the two tissues revealed a close similarity. Sodium dodecyl sulphate/polyacrylamide-gel electrophoresis showed the isolated enzyme to have a monomeric Mr of 52 000, and this was confirmed by h.p.l.c. gel exclusion at pH 5.0. The results of Sephadex G-100 chromatography at different pH values are taken to indicate that the enzyme behaves as a dimer at pH 7.0 and above, but as a monomer at pH 5.0. 4-Aminobutyrate aminotransferase isolated from the brain by the procedure of Fowler & John [(1981) Biochem. J. 197, 149-152] is more stable than the immunoaffinity-purified material, and has been shown to contain a contaminant protein of Mr 84 000 that exhibits succinic semialdehyde dehydrogenase activity.

A monoclonal antibody to rabbit brain GABA transaminase

A monoclonal antibody of class IgG (subclass IgG1) has been prepared to rabbit brain GABA transaminase (GABA-T). This antibody reveals a single band of molecular weight 52,000 on a nitrocellulose filter blotted with purified GABA-T. On a filter blotted with unfractionated rabbit brain supernatant a major band of molecular weight 58,000 is revealed. An immunoaffinity column was prepared by coupling proteins from ascites fluid containing anti-rabbit GABA-T antibody to Bio-Rad Affi-Gel 15. This column bound purified GABA-T and extracted from unfractionated rabbit brain supernatant a protein of molecular weight 58,000, which was almost homogeneous and which had GABA-T enzyme activity. Using immunoaffinity chromatography, therefore, a high degree of purification of GABA-T may be achieved in a single step. Further, this technique may preserve an authentic form of the enzyme that is lost during the conventional purification procedure. The antibody inhibits GABA-T enzyme activity, up to a maximum of 35%.

Reaction of muscimol with 4-aminobutyrate aminotransferase

The reaction of muscimol as amino donor substrate for GABA transaminase (GABA-T) has been studied using enzyme purified from rabbit brain. Enzyme activity was assayed by measuring the glutamate produced using glutamate dehydrogenase. Kinetic parameters determined at 37 degrees C were for GABA, Km (app) = 1.92 +/- 0.24 mM, specific activity = 7.33 +/- 0.27 mumol/min/mg (kcat = 13.7s-1), and for muscimol, Km (app) = 1.27 +/- 0.15 mM, specific activity = 0.101 +/- 0.009 mumol/min/mg (kcat = 0.19s-1). Addition of muscimol to the enzyme caused the spectral changes associated with conversion of the pyridoxaldimine form to the pyridoxamine form, and the first-order rate constant for the reaction showed a dependence on muscimol concentration that followed saturation kinetics, with a K = 1.1 +/- 0.18 mM and kmax = 0.065 +/- 0.004 s-1 (19 degrees C). The rate of spectral change observed on addition of muscimol to ornithine transaminase was extremely slow--at least an order of magnitude slower than that seen with GABA-T.

The effects of sodium valproate on gamma-aminobutyrate metabolism and behaviour in naive and ethanolamine-O-sulphate pretreated rats and mice

Sodium valproate was injected acutely (400 mg/kg i.p.) into naive and ethanoloamine-O-sulphate chronically pretreated rats and mice, in an attempt to gain further insight into the effects of this anticonvulsant on GABA metabolism. Sodium valproate significantly enhanced the activity of GAD in the medulla and pons, cerebellum and midbrain regions of rats, and partially relieved the suppression of GAD activity caused by chronic GABA-transaminase inhibition in whole mouse brain. In combination with EOS, sodium valproate caused behavioural excitation in mice which was similar to that sometimes seen with high doses of some GABA-T inhibitors. Pretreatment with EOS potentiated the characteristic abstinence behaviour caused by sodium valproate in rats, though no further significant rise in cerebral GABA levels was observed. In view of the neuronal location of GAD, the elevation of cerebral GABA levels at least in part by potentiation of GAD activity could be involved in the mediation of the anticonvulsant activity of sodium valproate.

A regional study of 4-aminobutyrate metabolism and amino acid levels in rat brain following chronic oral administration of ethanolamine O-sulphate

Ethanolamine O-sulphate (EOS) dissolved in the drinking water (5 mg . ml(-1) was administered ad libitum to rats for 26 days. At the end of this period, glutamate decarboxylase (GAD) and GAA-transaminase (GABA-T) activities, 4-aminobutyrate (GABA) concentration, and the levels of six other amino acids were measured in various brain regions. Significant inhibition of GABA-T accompanied by significant increases in GABA content were observed throughout the brain, although the magnitudes of these effects varied according to region. GAD activity was significantly reduced in most brain regions, although this effect was apparently not related to cofactor availability or the direct actions of EOS or increased GABA concentration. Glutamine levels were significantly reduced to approximately 72% of control values in all brain regions. Aspartate levels were significantly reduced to approximately 84% of control values in all regions except the striatum and cerebellum. Minor changes in other amino acid levels were also detected. These neurochemical changes which accompanied the primary effect of EOS on GABA-T are discussed in terms of indirect secondary metabolic changes rather than nonspecific enzyme inhibition by EOS.

The reaction of ornithine aminotransferase with ornithine

Rat liver ornithine aminotransferase is found to exchange the pro-S hydrogen on the delta-carbon atom of ornithine exclusively, thus showing that the mammalian enzyme transfers the delta-amino group and not the alpha-amino group as has been demonstrated with the plant enzyme [Mestichelli, Gupta & Spenser (1979) J. Biol. Chem. 254, 640-647]. The enzyme also transfers the alpha-amino group of glutamate and the kinetics of the half reactions between the enzyme and both amino acids are compared. Rate and dissociation constants for both reactions are determined.

The reaction of ethanolamine O-sulphate with 4-aminobutyrate aminotransferase

The enzyme-induced or 'suicide' step by which the substrate analogue ethanolamine O-sulphate inactivates 4-aminobutyrate aminotransferase occurs at a rate that is one-tenth that observed for the release of the products of beta-elimination, namely ammonia, acetaldehyde and sulphate. An additional reversible reaction not leading to inactivation can be detected spectrally and this decreases the rates of both beta-elimination and inactivation. This reaction is ascribed to a step on the normal transamination path, although complete transamination does not occur significantly. The 14C moiety of radiolabelled ethanolamine O-sulphate is stably bound to the inactive enzyme in the proportion of 1 mol/mol of active site. The 35S-labelled sulphate moiety is not bound after inactivation, showing that beta-elimination must precede inactivation.

Enzyme-induced inactivation of transminases by acetylenic and vinyl analogues of 4-aminobutyrate

The reactions of two analogues of 4-aminobutyrate, namely 4-aminohex-5-ynoate and 4-aminohex-5-enoate, with three transaminases were studied. Three pure enzymes were used, aminobutyrate transaminase (EC 2.6.1.19), ornithine transaminase (EC 2.6.1.13) and aspartate transaminase (EC 2.6.1.1), and the course of the reactions was studied by observing changes in the absorption spectrum of the bound coenzyme and by observing loss of activity. All of the enzymes were inactivated by either inhibitor, but amino-hexenoate showed a marked specificity for aminobutyrate transaminase. Aminohexynoate was most potent towards ornithine transaminase, and with this enzyme transamination of the inhibitor is an important factor in protecting the enzyme. Most of the reactions could be analysed as first order, with the observed rate constant showing a hyperbolic dependence on inhibitor concentration.

Kinetic and spectral properties of rabbit brain 4-aminobutyrate aminotransferase

Purification and 4-aminobutyrate-2-oxoglutarate aminotransferase (EC 2.6.1.19) from rabbit brain is described. The method was used as a routine to give between 5 and 10mg of pure enzyme from 750 g of rabbit brain. The enzyme is a dimer made up of subunits each with a mol. wt. of 58000. An absorption spectrum of the freshly prepared enzyme shows peaks at 415 and 330 nm. Treatment of the enzyme with the substrate 4-amino-butyrate or glutamate produces a decrease in the 415 nm and an increase in the 330 nm peak. This conversion, which is attributed to an aldimine into ketimine step in the reaction, is sufficiently slow when 4-aminobutyrate is the substrate to allow it to be followed by stopped-flow spectrophotometry. A first-order rate constant was determined for this step (12s-1) and compared with the turnover number for the enzyme derived by steady-state methods (9.5S-1). The first-order rate constant when glutamate was used as substrate was estimated to be approx. 30s-1.