Contrasting baroreflex effects of muscimol versus bicuculline injected into the nucleus tractus solitarius in anesthetized rats

To examine how the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) affects baroreflex regulation, reflex heart rate and renal nerve responses were recorded in anesthetized rats after bilateral injections of muscimol or bicuculline into the nucleus tractus solitarius (NTS). Blood pressure, heart rate, and renal nerve activity were increased by the GABA agonist muscimol and decreased by the GABA antagonist bicuculline. Control injections of the vehicle alone were ineffective. More importantly, all reflex responses later induced by infusing phenylephrine or sodium nitroprusside intravenously were reduced by muscimol. The magnitude of the reflex bradycardia and sympathoinhibition caused by phenylephrine, as well as that of the reflex tachycardia and sympathoexcitation caused by sodium nitroprusside, diminished after NTS injections of muscimol. By contrast, the same reflex responses tended to be enhanced after NTS injections of bicuculline, but most changes were not significant. If GABA acts on receptors located on second-order neurons in the NTS, then muscimol would inhibit those neurons, whereas bicuculline would prevent endogenous GABA from reaching them. Thus muscimol would reduce reflex responsiveness by inhibiting all second-order neurons, whereas bicuculline would enhance it by protecting the same neurons from inhibition by endogenous GABA.

Nucleotide sequence of a principal sigma factor gene (hrdB) of Streptomyces griseus

The hrdB homologue was isolated from a streptomycin-producing Streptomyces griseus 2247 strain, which is independent of A-factor. The nucleotide sequence of the cloned DNA fragment revealed the presence of an open reading frame (ORF) of 1,542bp, which predicted a primary product of 514 amino acids and Mr 56,100. The N-terminal sequence of the purified HrdB protein of S. griseus was identical to the amino acid sequence deduced from the nucleotide sequence. The deduced amino acid sequence contains an "rpoD box" conserved in the principal sigma factors of eubacteria, and shows high similarity to the hrdB products of S. coelicolor A3(2)(89.9%) and S. aureofaciens (88.1%). The cloned gene encodes a principal sigma factor of S. griseus. The promoter region was identified by using a promoter-probe vector and by means of primer extensions experiments. The transcription start point is located 158-bp upstream of the initiation codon.

The potent and selective inhibition of estrogen production by non-steroidal aromatase inhibitor, YM511

YM511 inhibited aromatase activities in microsomes from rat ovary and human placenta competitively (IC50s: 0.4 and 0.12 nM, respectively). YM511 was about 3 times more potent than other aromatase inhibitors, such as CGS 16949A, CGS 20267 and R 76713. YM511 decreased the contents of estradiol stimulated by pregnant mare's serum gonadotropin in rat ovary with an ED50 of 0.002 mg/kg, indicating that YM511 was equipotent to CGS 20267 and 3 times more potent than the other two inhibitors. Serum estradiol levels in female rats were reduced by YM511 at 0.01 mg/kg into the ovariectomized range. YM511 at 1 mg/kg for 2 weeks decreased rat uterine weight to levels comparable to ovariectomy, showing it was 10 times more potent than other inhibitors. But the maximal inhibitory effect of tamoxifen failed to reach ovariectomized level. YM511 slightly inhibited production of other steroid hormones in vitro and in vivo. The IC50s of YM511 for aldosterone and cortisol production from adrenal cells were from 5500 to 9800 times higher than that for rat ovarian aromatase and 130,000 times higher for testosterone production, indicating that YM511 is a highly specific aromatase inhibitor. The data suggest that YM511 may be a potent and selective agent for suppressing estrogen-dependent action without affecting serum levels of other steroid hormones.

A human monoclonal antibody to a human self-antigen, CD2 derived from human peripheral blood lymphocytes engrafted in SCID mice

To establish human hybridoma lines, production of human immunoglobulin (Ig) and behavior of the implanted human peripheral blood lymphocytes (PBL) were characterized in severe combined immunodeficiency (SCID) mice. Human PBL from healthy donors were injected into the peritoneal cavity of SCID mice, and they were immunized with self-antigen, CD2. CD45+ cells (human PBL) migrated to lymphoid tissues in the mice as early as 4 days, accounting for more than half the lymph node cells and thymocytes. The number of cells releasing human IgG specific to the antigen increased 3.5 weeks after immunization without the usual constraint that production of the IgG, an autoantibody, is prohibited by immunological tolerance in humans. Therefore, we established several human hybridomas secreting human IgG to CD2, since splenocytes and lymph node cells from the implanted SCID mice at 3.5 weeks were fused with a human B lymphoblastoid cell line. A human anti-CD2 monoclonal antibody (MAb) was confirmed to bind to natural CD2 on human T cells by flow cytometric analysis. The epitope for the MAb was identical with a portion that the ligand LFA-3 binded, so that the MAb might reduce the inflammatory reaction caused by preventing activation of human T cells. Here, we report that the human immune system could be reconstituted in SCID mice to develop human hybridomas producing human MAb to a human self-antigen.

[A case of papillary muscle rupture associated with acute inferior myocardial infarction]

A sixty-year-old man was admitted to our hospital due to prolonged left anterior chest oppression and hypotention. The electrocardiogram revealed acute inferior myocardial infarction, confirmed by the coronary angiography which showed occluded right coronary artery (RCA) at the segment 4AV. The intra-coronary pro-urokinase infusion and coronary angioplasty successfully revascularized the occluded 4AV segment. Although the 4AV segment perfused small area, he developed severe pulmonary edema on the second hospital day. A transesophageal echocardiography revealed severe mitral regurgitation due to posterior mitral valve prolapse by the ruptured tendineae with a mobile mass. The damaged mitral valve was replaced by the prosthetic mechanical valve (SJM 25M), resulted in stable hemodynamic state. He discharged one month after the operation.

Dopaminergic system mediation of stimulatory effect of melatonin on secretion of prolactin

OBJECTIVE

The purpose of the present study was to clarify the mechanism of the stimulatory effect of melatonin on the secretion of prolactin.

METHODS

Determination was made of the levels of dopamine (DA), 3,4-dihydroxyphenlacetic acid (DOPAC), serotonin (5-HT), and 5-hydroxyindoleacetic acid (5-HIAA) in the median eminence of rats following intravenous melatonin (100 micrograms) administration.

RESULTS

Administration of 100 micrograms of melatonin to rats resulted in a significant increase in prolactin secretion (p < 0.01, analysis of variance). Administration of melatonin also resulted in significant decreases in the DOPAC content (p < 0.05) and in the DOPAC/DA ratio (p , 0.05) in the median eminence 1 hour after melatonin administration, at which time serum prolactin was maximal. However, no significant changes were detected in the content of 5-HT or 5-HIAA or in the 5-HIAA/5-HT ratio in the median eminence.

CONCLUSION

These results suggest that the stimulatory effect of melatonin on the secretion of prolactin might be mediated by dopaminergic mechanisms.

Genomic organization and isoforms of the mouse ELP gene

Analysis was made on the genomic structure, functions, and expression of the mouse ELP gene, which codes for the embryonal long terminal repeat binding protein. Extensive screening of the cDNA library of embryonal carcinoma cells (EC cells) identified four isoforms of ELP: ELP1 (the original ELP isolate), ELP2, ELP3, and Ad4BP/SF1. Analysis of the genomic sequences revealed that these ELP isoforms were generated by alternative promoter usage and differential splicing. The mRNAs of isoforms initiated at four transcription start sites distributed on three exons. Sequence analysis of the four isoforms identified three polypeptides. The N-terminal portion of ELP1 and ELP2 was longer than ELP3, and Ad4BP/SF1 by 77 aa. The DNA-binding domain and region II were shared by all four isoforms. The C-terminal portion shared by ELP2, ELP3, and Ad4BP/SF1 was 131 aa in length, and that specific to ELP1 was 57 aa in length. The ELP3 and Ad4BP/SF1 isoforms were identical for the coding sequence, but the two differed at the 5' noncoding region. Region II and III domains of nuclear receptors were thought to be involved in ligand-binding and transcriptional activation. ELP1, which lacked region III, functioned as a repressor. The isoforms carrying intact region II and region III functioned as transactivators. Expression of the four isoforms was studied in mouse tissues and in tissue culture cells by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. Complex patterns of expression of these isoforms were observed in various tissues. All four ELP isoforms were expressed only in EC cells.

Establishment of canine pulmonary hypertension with dehydromonocrotaline. Importance of larger animal model for lung transplantation

Single lung isografting in rats with pulmonary hypertension has been reported. However, it is hard to evaluate cardiopulmonary hemodynamics accurately or to use circulatory assists during procedures using rats. Therefore, we tried to establish a model of pulmonary hypertension in the beagle. Twenty young beagles were randomized into 3 groups. An injection of dehydromonocrotaline of 1.5 mg/kg (group 1, n = 7), 3.0 mg/kg (group 2, n = 10), or 4.5 mg/kg (group 3, n = 3) was performed via the right atrium. Two dogs in group 2 and all the dogs in group 3 died of acute pulmonary edema. During the 8 weeks after injection, the systolic pulmonary arterial pressure and pulmonary vascular resistance index increased significantly in group 2 from 21 +/- 2 to 56 +/- 9 mmHg and from 106 +/- 39 to 826 +/- 176 dynes.sec.cm-5.m2, respectively (P < 0.01). The changes in group 1 were less pronounced. The dogs in group 2 also had a rise in their plasma endothelin-1. Pathologic analysis revealed thickening of the media in small pulmonary arteries and hypertrophy of the right ventricular myocardium. Our data indicate that beagles treated with 3.0 mg/kg dehydromonocrotaline produced a unique, relatively noninvasive model of pulmonary hypertension. In the model, right ventricular failure prevented us from clamping one pulmonary artery. These relatively large animals with pulmonary hypertension will be valuable for further studies of lung transplantation.

Acute left atrial thrombus causing cardiogenic shock following mitral valve replacement: report of a case

We report herein the rare case of a 53-year-old woman who developed cardiogenic shock due to an acute left atrial thrombus following replacement of the mitral valve. A definitive diagnosis was not able to be made using precordial echocardiography because of the broad, flat shape of the thrombus; however, transesophageal echocardiography imaged the thrombus in detail. The patient was initially stabilized by percutaneous cardiopulmonary support after which a thrombectomy was successfully performed.

Correlation between anti-ubiquitin immunoreactivity and region-specific neuronal death in N-methyl-D-aspartate-treated rat hippocampal organotypic cultures

Neuronal degeneration appears to be associated with changes in anti-ubiquitin immunoreactivity (UIR). To elucidate the relationship between the two events, we examined the time course of changes in UIR in pyramidal neurons of hippocampal organotypic cultures following exposure to an excitotoxin, N-methyl-D-aspartate (NMDA). In nontreated cultures, weak UIR was confined to the nucleus. Exposure to 100 microM NMDA for 15 min induced degeneration of pyramidal neurons, within 24 h, in the CA1 and CA3c regions. In these neurons, the nuclear UIR was reduced, and instead, UIR developed in the cytoplasm. In response to the same procedure, CA3a,b pyramidal neurons showed slight shrinkage but otherwise virtually normal morphological features. Little perikaryal (cytoplasmic) UIR developed in CA3a,b neurons. Both degeneration and perikaryal UIR were observed in CA3a,b neurons, however, when the culture was exposed to 300 microM NMDA. Immunoblot analysis showed that changes in the amount of a ubiquitin protein conjugate (24 kDa), presumably ubiquitinated histone, are similar to those of nuclear UIR in the same time course. We propose that the changes in the expression of nuclear and perikaryal ubiquitinated proteins represent some process closely related to neuronal death.

Role of endothelin-1 in beagles with dehydromonocrotaline-induced pulmonary hypertension

BACKGROUND

Although plasma levels of endothelin-1 (ET-1) increase in patients with pulmonary hypertension (PH), its role in PH is unknown. We investigated the contribution of endogenous ET-1 to cardiopulmonary changes in beagles with dehydromonocrotaline (DMCT)-induced PH.

METHODS AND RESULTS

Eight 3-month-old beagles were given a single injection of 3 mg/kg DMCT via the right atrium. During the 8 weeks after injection, the mean pulmonary arterial pressure (PAP) and plasma ET-1 level increased significantly from 11.6 +/- 2.3 to 35.9 +/- 7.1 mm Hg and from 1.24 +/- 0.25 to 3.25 +/- 0.94 pg/mL, respectively. In controls, ET-1 infusion elevated the systemic arterial pressure (SAP) but did not alter PAP. In PH beagles, ET-1 infusion increased SAP, which was attenuated by FR139317 (an endothelin type [ET] A receptor antagonist), and produced a dose-dependent decrease in PAP, which was attenuated by RES-701-1 (an ETB receptor antagonist). In PH beagles, FR139317 infusion decreased PAP, and RES-701-1 infusion increased PAP. Sarafotoxin S6c (an ETB agonist) infusion decreased PAP in PH beagles.

CONCLUSIONS

These results suggest that endogenous ET-1 is elevated in PH disease and may mitigate PH by acting on ETB receptors.

[Use of epicardial leads for transvenous pacing lead insufficiency with venous thrombosis: a case report]

Recent progress in the electrode tip to prevent dislodgement makes difficult to extract itself in some patients. And when multiple leads are placed through a transvenous route, more frequent occurrence of venous thrombosis is easily suspected. We experienced a case of transvenous lead insufficiency with venous thrombosis. In this patient, two of unextractable transvenous leads were already placed, and venous thrombosis was detected by venography, so we implanted the new epicardial leads instead. In case of long-term placement of transvenous leads, especially when multiple, the possibility of venous thrombosis is ever thought, and the use of the extractable leads or anticoagulant therapy is recommended.

Vitamin B6 modulates expression of albumin gene by inactivating tissue-specific DNA-binding protein in rat liver

The level of albumin mRNA in the liver of vitamin B6-deficient rats was found to be 7-fold higher than that of control rats. Since the transcriptional activity of the albumin gene, as measured by a nuclear run-on assay, was increased 5-fold in vitamin B6 deficiency, the higher concentration of albumin mRNA in the liver of vitamin-deficient rats could be attributed to the enhanced rate of transcription. The promoter proximal sequences of the albumin gene interact with a number of tissue-specific transcription factors including HNF-1 and C/EBP. We determined the binding activities of liver nuclear extracts to the HNF-1- and C/EBP-binding sites by gel mobility-shift assay and found that the activities of the extract prepared from liver of vitamin B6-deficient rats were greater than those of controls. As the concentrations of C/EBP in nuclear extracts from control and vitamin-deficient rats, estimated by Western-blot analysis, were essentially the same, the lower binding activity of the extract from control liver is probably due to inactivation of tissue-specific factors by pyridoxal phosphate and/or its analogues. We therefore examined the effect of pyridoxal phosphate and its analogues on the binding activity of nuclear extract in vitro and found that only pyridoxal phosphate effectively inhibited the binding. These observations indicate that vitamin B6 modulates albumin gene expression through a novel mechanism that involves inactivation of tissue-specific transcription factors by direct interaction with pyridoxal phosphate.

Abolition of suppressive effect of acute myeloid leukemia cells on normal granulocyte-macrophage colony formation induced by interleukin-5 associated with eosinophilic cell induction

The effects of recombinant interleukin-5 (rIL-5) on leukemic blasts obtained from 22 acute myeloid leukemia (AML) patients were investigated. Recombinant IL-5 stimulated leukemic colony formation in the leukemic blasts of 50% of the patients (11/22), and in 7 of these 11 cell cultures leukemic eosinophilic colonies were induced. Eosinophilic cell induction was associated with cellular proliferation, that is, colony or cluster formation. Leukemic blasts cultured with rIL-5 and forming eosinophilic colonies no longer suppressed normal granulocyte-macrophage colony formation, suggesting that functional differentiation of these leukemic blasts took place. Induction of this type of functional differentiation of leukemic blasts may be of clinical value in promoting normal hematopoiesis.

[A surgical case of aortic dissection Stanford type A caused by blunt chest trauma--a report of a successful case]

A case of successfully repaired traumatic aortic dissection was reported. A 66-year-old woman with a blunt chest trauma from the car accident was transferred to our hospital. The radiological examination revealed Stanford type A aortic dissection without aortic regurgitation. Because of disturbance of consciousness and respiratory failure due to the associated blunt lung injury, she was treated in the intensive care unit, and, after 1 month, a graft replacement of the ascending aorta by using deep hypothermia with retrograde cerebral perfusion was carried out. The postoperative course was uneventful. Blunt chest trauma is very rare to cause aortic dissection, and the operative indication should be determined with careful consideration of the associated organ injuries.

Indocyanine green videoangiographic findings in choroidal metastatic tumor

BACKGROUND

Indocyanine green videoangiography (ICGV) has recently advanced and become widely available as a clinical tool. We tested the efficacy of ICGV in evaluating metastatic choroidal tumors.

METHODS

ICGV using Topcon 50-IA was performed in five patients with clinically diagnosed choroidal metastatic tumors. The findings were compared with those of conventional fluorescein angiography (FAG).

RESULTS

Compared with FAG, ICGV demonstrated more smooth and regular hypofluorescent lesions, precisely indicating the exact size of the tumor. In all cases, no tumor vessels were found. The choroidal vascular integrity around the tumors was observed. FAG, however, was more sensitive in detecting the tumor development than ICGV when the extent of the hypofluorescent lesion could be seen clearly in the early phase. FAG provided more information regarding retinal pigment epithelial dysfunction in the outer blood retinal barrier overlying the tumor.

CONCLUSION

Since ICGV enables visualization of tumors through the retina, it is very useful, particularly in cases of associated secondary retinal detachment around the tumors. ICGV combined with FAG provides more precise assessment of the tumors themselves and their response to treatment than FAG alone.

Pharmacologic intervention for ischemic brain edema after retrograde cerebral perfusion

Retrograde cerebral perfusion has recently been the focus of interest as a simple new technique of brain protection during aortic arch operations. We undertook the experimental protocol of 120 minutes of retrograde cerebral perfusion followed by antegrade reperfusion. Eighteen mongrel dogs were used. Retrograde cerebral perfusion was maintained at a flow rate of 150 to 250 ml/min to keep the perfusion pressure from 15 to 25 mm Hg. Animals were divided into three groups as follows: in group I, no treatment was received during and after retrograde cerebral perfusion; in group II, mannitol (2 gm/kg) was administered before cardiopulmonary bypass was restarted; and in group III, antivasospastic substance (1,2-bis nicotinamido]-propane) was continuously injected during and after retrograde cerebral perfusion (1 mg/kg per minute). Cerebral blood flow decreased during retrograde cerebral perfusion in all three groups. Cerebrovascular resistance showed marked increases 30 and 60 minutes after cardiopulmonary bypass was restarted in group I compared with the values in groups II and III (group I: 3.35 +/- 0.73 and 5.00 +/- 1.57 mm Hg/ml per 100 gm per minute; group II: 1.30 +/- 0.33 and 1.03 +/- 0.17 mm Hg/ml per 100 gm per minute; group III: 1.24 +/- 0.41 and 0.98 +/- 0.24 mm Hg/ml per 100 gm per minute). The oxygen extraction level was reduced by cooling, but it rose to a higher level as a result of significant desaturation of returned blood even in deep hypothermia during retrograde cerebral perfusion. Both cerebral metabolic rate of oxygen and cerebral metabolic rate of glucose remained at low levels during retrograde cerebral perfusion. Ratios of cerebral blood flow to cerebral metabolic rate of oxygen and cerebral blood flow to cerebral metabolic rate of glucose were markedly reduced during retrograde cerebral perfusion. Intracranial pressure showed significant increases 30 and 60 minutes after cardiopulmonary bypass was restarted in group I compared with values in group II or group III (group I: 22.7 +/- 2.8 and 20.6 +/- 5.1 mm Hg; group II: 6.3 +/- 1.8 and 5.3 +/- 1.3 mm Hg; group III: 4.2 +/- 1.7 and 7.7 +/- 2.8 mm Hg). Water content of the brain tissue in group I (77.54% +/- 0.29%) was significantly higher than that in group II (74.71% +/- 0.76%) or group III (74.14% +/- 0.48%). These data suggest that the supply of oxygen or glucose by retrograde cerebral perfusion is not enough to maintain sufficient cerebral metabolism, which may cause brain edema during antegrade reperfusion.(ABSTRACT TRUNCATED AT 400 WORDS)

Pyridoxal 5'-phosphate modulates expression of cytosolic aspartate aminotransferase gene by inactivation of glucocorticoid receptor

The level of mRNA for cytosolic aspartate aminotransferase (cAST) in the liver of vitamin B6-deficient rats was found to be 7-fold higher than that of the control rats. The administration of hydrocortisone to adrenalectomized vitamin B6-deficient rats induced expression of hepatic cAST mRNA and the induction was suppressed by the simultaneous administration of pyridoxine. Since the 5' regulatory region of the rat cAST gene contains several sequences showing homology to glucocorticoid-responsive elements, we synthesized an oligonucleotide probe of glucocorticoid-responsive element sequence and assayed the binding activity of liver nuclear extract to the oligonucleotide by gel mobility shift analysis. We found that the binding activity of nuclear extract prepared from the liver of vitamin B6-deficient rats was far greater than that of the control rats, indicating that the DNA-binding activity of glucocorticoid receptor was enhanced by vitamin B6 deficiency. We further found that preincubation of the nuclear extract from the vitamin-deficient liver with pyridoxal 5'-phosphate brought about a rapid and extensive decrease in the binding of the extract to the glucocorticoid-responsive element. Congeners of pyridoxal phosphate, such as pyridoxamine 5'-phosphate, pyridoxal, pyridoxamine and pyridoxine, did not show an inhibitory effect. These observations suggest that pyridoxal 5'-phosphate modulates cAST gene expression by inactivating the binding activity of glucocorticoid receptor to glucocorticoid-responsive elements.

Possible inhibitory effect of lithium on peripheral conversion of thyroxine to triiodothyronine: a prospective study

The effect of lithium on thyroid function was studied in 18 neuroleptic-treated male chronic schizophrenic in-patients. Lithium carbonate was administered for 8 weeks at a dosage giving a mean serum level of 0.79 mmol/l. Blood was obtained just before and after 8 weeks of lithium administration to determine the serum free thyroxine (free T4) levels, free triiodothyronine (free T3) levels and thyrotropin (TSH) levels. Overall, free T4 and TSH levels significantly increased whereas free T3 levels did not change. Two (11%) patients had abnormally increased free T4 levels and abnormally decreased free T3 levels after 8 weeks of lithium administration. These findings suggest that lithium may inhibit the peripheral conversion of free T4 to free T3 in some susceptible patients.

Evoked otoacoustic emissions and electrocochleography in a patient with multiple sclerosis

A 24-year-old woman with multiple sclerosis had right-sided hearing impairment with tinnitus. She underwent electrocochleography (ECochG) and examination of evoked otoacoustic emissions (EOAEs) to assess cochlear function. An acoustic probe to measure EOAEs was inserted into the external ear canal. The ECochG action potential and cochlear microphonics were recorded by a transtympanic needle electrode technique. Both fast and slow components of EOAEs appeared in either the period of deteriorated hearing acuity or when it was improved. They showed normal detection thresholds and input-output curves during both periods. Cochlear microphonics with almost normal detection thresholds and input-output functions were obtained during the period of deteriorated hearing acuity. Action potential (N1) input-output curves during relapse with hearing loss were notably lower in amplitude and longer in latency than those obtained at the time hearing impairment showed improvement. The EOAE and ECochG findings suggested that this patient had almost normal cochlear function, and we assumed from the magnetic resonance imaging and auditory brain stem response findings as well as the ECochG that the hearing impairment was caused by dysfunction of auditory pathways in the brain stem, including structures that contribute to generation of the N1 potential of the ECochG.

Mislocalization of oskar product in the anterior pole results in ectopic localization of mitochondrial large ribosomal RNA in Drosophila embryos

Mitochondrial large ribosomal RNA (mtlrRNA) was identified as a cytoplasmic factor that induces pole cells in uv-irradiated embryos and is localized on polar granules in normal embryos at early stages. Here, we report that mtlrRNA is localized in the anterior pole if oskar products are forced to be localized there. This clearly shows, contrary to the previous report by Ding et al. (1994, Developmental Biology 163, 503-515), that localization of mtlrRNA depends on oskar function even at the anterior pole.

Long-term spatial cognitive impairment following middle cerebral artery occlusion in rats. A behavioral study

Behavioral changes in the chronic phase of permanent occlusion of the right middle cerebral artery (MCA) in rats were investigated. One month after MCA occlusion, 23 rats were unable and 7 rats were able to solve a radial 8-arm maze task during a 1-month period. Three months after occlusion, 19 MCA-occluded rats failed to solve the task successfully again during at least a 1-month period (the cognitively impaired rats), and 11 MCA-occluded rats were able to solve it (the cognitively unimpaired rats). When a delay of 60 min was imposed for this task, five cognitively unimpaired rats failed to solve it. The locomotor activity of the cognitively impaired rats increased significantly 2 months after occlusion, and this increase showed good correlation with spatial cognitive deficit. However, the mean time a rat spent at each arm remained unchanged among the cognitively impaired, unimpaired, and sham-operated rats. There was no significant difference in the ratio between the cognitively impaired and unimpaired rats for disturbed motor coordination. These results suggest that MCA occlusion is capable of producing long-term spatial cognitive disturbance in rats. In addition, this spatial cognitive deficit does not seem to be primarily due to hypermotility or a disturbance in motor coordination.

A further prospective evaluation of an equation to predict daily lithium dose

BACKGROUND

Recently, one prospective study confirmed the safety and accuracy of a lithium-dose prediction equation created by Zetin et al., but no definitive conclusion on the reliability of the equation has been established as yet.

METHOD

The authors applied the Zetin et al. equation to 18 chronic male schizophrenic inpatients. Predicted doses to reach the serum lithium concentration of 0.4 mmol/L were calculated and prescribed in the form of lithium capsules. At Weeks 1 and 3 after treatment initiation, morning blood samples were collected about 12 hours after the last lithium dose for the measurement of serum lithium concentrations.

RESULTS

None of the 18 patients achieved the desired concentration (0.4 mmol/L) exactly. The mean +/- SD of serum lithium concentrations at Week 1 was 1.01 +/- 0.29 mmol/L (range, 0.2-1.5) and at Week 3 was 0.94 +/- 0.35 mmol/L (range, 0.2-1.8). Lithium concentrations were lower than 0.4 mmol/L in only 1 patient and were higher than 0.4 mmol/L in the other 17 patients. The deviations from the unexpected value were significantly correlated with the renal function (blood urea nitrogen and serum creatinine levels) but not with the neuroleptic doses administered to the patients. Moreover, our patients were relatively older and weighed relatively less than the patients described in the previous prospective study.

CONCLUSION

The Zetin et al. equation cannot always accurately predict a required lithium dose. Renal function data, even when they range within normal values, may be useful to improve the accuracy of the equation, particularly in patients who are older or weigh less than the norm.