Cerebellum of the adult reeler mutant mouse contains two Purkinje cell populations with respect to gene expression for the N-methyl-D-aspartate receptor channel

Recent studies have identified five NMDA receptor subunits, which exhibit distinct cellular expressions in the normal rodent brain. The purpose of this investigation is to clarify the molecular-anatomical organization in the cerebellum of the reeler mutant mouse, in which various categories of the Purkinje cells are present as to the cell position and synaptic connectivity. In comparison with the distribution of the inositol 1,4,5-trisphosphate receptor mRNA, a molecular marker specific to the Purkinje cells, the epsilon 1 subunit mRNA of the NMDA receptor channel was found in the adjacent sections to be expressed in a subset of the Purkinje cells. In the rostrocaudal extent, the Purkinje cells expressing the epsilon 1 subunit mRNA were distributed preferentially in the rostral cerebellum, irrespective of the normal and heterotopic positions. In the mediolateral extent, they formed segregated cell clusters, interposed by epsilon 1 subunit mRNA-negative clusters. Hybridizing signals for the zeta 1 subunit mRNA were found in all the Purkinje cell population, whereas those for the epsilon 2, epsilon 3, and epsilon 4 subunit mRNAs were not detected in the cells. These findings suggest that the reeler cerebellum is topographically compartmentalized by two subpopulations of the Purkinje cells, one expressing the epsilon 1 and zeta 1 subunit mRNAs, and the other expressing the zeta 1 subunit mRNA alone.

Neural crest cell-cell adhesion controlled by sequential and subpopulation-specific expression of novel cadherins

We identified two cadherins, c-cad6B and c-cad7, expressed by neural crest cells at their premigratory and migratory stages, respectively, in chicken embryos. cDNA transfection experiments showed that both were homophilic adhesion molecules, endowing cells with specific adhesiveness. During development, c-cad6B appeared in the neural fold, localizing at the future neural crest area. This expression was maintained during neural tube closure, but disappeared after neural crest cells had left the neural tube, suggesting its role in neural fold fusion and/or in the formation and maintenance of the presumptive neural crest domain in the neural plate/tube. Crest cells emerging from the neural tube lost c-cad6B, and a subpopulation of them began to express c-cad7. This subpopulation-specific expression of c-cad7 persisted during their migration. The migrating c-cad7-positive cells clustered together, and eventually populated restricted regions including the dorsal and ventral roots but very little ganglia. The latter was populated with N-cadherin-positive crest cells. Migrating neural crest cells expressed alpha- and beta-catenin at cell-cell contacts, indicating that their cadherins are functioning. These results suggest that the migrating crest cells are grouped into subpopulations expressing different cadherins. The cadherin-mediated specific interaction between crest cells likely plays a role in intercellular signaling between homotypic cells as well as in sorting of heterotypic cells.

Ascorbic acid stimulates barrier function of cultured endothelial cell monolayer

The macromolecular permeability of cultured bovine aortic, bovine venous, and human umbilical vein endothelial cell monolayers was decreased significantly in culture medium containing L-ascorbic acid (Asc Acid; 0.01-0.1 mM) and L-ascorbic acid 2-phosphate (Asc 2-P). Dithiothreitol, which shows reducing activity equivalent to that of Asc Acid, did not affect endothelial permeability. Asc Acid induced a sixfold increase in collagen synthesis by the endothelial cells. The coexistence of L-azetidine 2-carboxylic acid, an inhibitor of collagen synthesis, attenuated the effect of Asc 2-P in a dose-dependent manner. Another collagen synthesis inhibitor, ethyl-3,4-dihydroxybenzoate, also inhibited collagen synthesis and increased endothelial permeability. The decrease in permeability of the endothelial monolayer was dependent on a reduction of the permeability coefficient of the endothelial monolayer. These findings indicate that endothelial barrier function is stimulated by Asc Acid via an increase in collagen synthesis.

Molecular design of hybrid tumour necrosis factor alpha with polyethylene glycol increases its anti-tumour potency

This study was conducted to increase the anti-tumour potency and reduce the toxic side-effects of tumour necrosis factor alpha (TNF-alpha). Natural human TNF-alpha was chemically conjugated with monomethoxy polyethylene glycol (PEG) using succinimidyl coupling of lysine amino groups of TNF-alpha. The number-average molecular weight of PEG-modified TNF-alpha (PEG-TNF-alpha) increased with an increase in the reaction time and the initial molar ratio of PEG relative to TNF-alpha. The resulting modified TNF-alpha was separated into fractions of various molecular weights. The specific activity of separated PEG-TNF-alpha s relative to that of native TNF-alpha gradually decreased with an increase in the degree of PEG modification, but the plasma half-life was drastically increased with the increase in molecular weight of modified TNF-alpha. PEG-TNF-alpha s, in which 29% and 56% of lysine residues were coupled to PEG, had anti-tumour activity approximately 4 and 100 times greater than unmodified TNF-alpha in the murine Meth-A fibrosarcoma model. Extensive PEG modification did not increase its in vivo activity. A high dose of unmodified TNF-alpha induced toxic side-effects, but these were not observed with the modified TNF-alpha s. Optimal PEG modification of TNF-alpha markedly increased its bioavailability and may facilitate its potential anti-tumour therapeutic use.

Multiple neurofibromas of the spinal nerve roots

This report describes a rare case of a suspected neurofibromatosis type 1 patient who had multiple bilateral spinal neurofibromas from the cervical to the sacral spinal dorsal nerve roots. The lesions were readily detected by MR imaging and the largest tumour was successfully resected. We provide a brief review of the literature, emphasising the usefulness of MR imaging in the diagnosis and evaluation of spinal neurofibromas.

[Evaluation of surgical treatment for bone metastatic lesion in renal cell carcinoma]

Ten renal cell carcinoma (RCC) patients with bone metastatic lesions were treated in the Kyoto Prefectural University of Medicine between January, 1977, and December, 1992. Surgical treatment for the metastatic lesion was performed on 4 patients, while conservative treatment was performed on the other 6 patients. Surgical treatment made the patients painless consecutively, resulting in higher activities of daily life. However, recurrence of RCC developed in all the cases between 2 and 7 years later. Surgical treatment for the metastatic lesion was considered to be only a palliative therapy for RCC with bone metastasis and the indication should be limited to patients expected to have a good prognosis.

Nucleotide sequence of the FAD synthetase gene from Corynebacterium ammoniagenes and its expression in Escherichia coli

The nucleotides of a bifunctional enzyme FAD synthetase gene, which showed both flavokinase and ATP:FMN adenylyltransferase activities, from Corynebacterium ammoniagenes were sequenced. The FAD synthetase gene product consisted of 338 amino acids and had a calculated molecular weight of 37,712. The deduced protein sequence of the FAD synthetase shared a homology with those of the protein X of Escherichia coli, which has been reported to have both flavokinase and ATP:FMN adenylyltransferase activities like the FAD synthetase of C. ammoniagenes, and the protein X of Pseudomonas fluorescens. From the analysis of the flanking sequences of the FAD synthetase gene, the gene organization and the operon structure around the FAD synthetase gene of C. ammoniagenes were thought to be different from those of Gram-negative bacteria. An over-expression system of the FAD synthetase of C. ammoniagenes was constructed in E. coli to study the structure and function of the protein. Under the tandem tryptophan promoter, the FAD synthetase activity increased 2231 times compared to that of non-transformed C. ammoniagenes.

Light- and electron-microscopic localization of the glutamate receptor channel delta 2 subunit in the mouse Purkinje cell

The localization of the glutamate receptor channel delta 2 subunit was investigated by immunohistochemistry. The delta 2-immunoreactivity was observed exclusively in the molecular layer of the cerebellar cortex. The electron microscopic analysis showed that the delta 2 subunit was localized in the dendritic spines of the Purkinje cells. The immunopositive spines often formed synaptic contacts with parallel fiber varicosities. As for the Purkinje cells ectopically localized in the cerebellar nuclei and brain stem, the dendritic shafts and cell bodies were strongly labeled. These ectopic Purkinje cells also formed asymmetrical synapses at the delta 2-immunopositive dendritic spines. Considering the specific localization of the delta 2 subunit in the postsynaptic site of the Purkinje cells, the subunit is suggested to be involved in the excitatory synaptic transmission in the cells, as a component of the glutamate receptor channel.

Lobectomy for traumatic pulmonary pseudocysts with disseminated intravascular coagulation: case report

A 10-year-old boy was injured in a traffic accident, and computed tomography revealed cavitary pulmonary lesions in the left lower lobe. Although there was no evidence of bacterial infection, thrombocytopenia due to disseminated intravascular coagulation progressed. We performed a left lower lobectomy, and the patient improved rapidly.

Tumor-conditioned medium increases macromolecular permeability of endothelial cell monolayer

The permeation of macromolecular FITC-labeled dextran (molecular weight 70,000) through bovine aortic endothelial cells (BAEC) monolayer, which were cultured for 5 days with conditioned medium prepared from mouse melanoma B16, was increased. However, when BAEC, which were cultured with normal medium until confluent, were treated with B16 conditioned medium (B16-CM) for 30 min, the permeability did not increase. The B16-CM also increased the permeability of the endothelial monolayers of bovine veins and the human umbilical vein, but did not increase that of the epithelial monolayer. The B16-CM did not alter the distribution or content of F-actin on the BAEC. BAEC cultured in the presence of B16-CM for 5 days were detached from the dish, and then seeded into a chamber at one-fifth of confluent cell density. After 5 days of culture in normal medium, the BAEC were grown to confluence and their permeability was increased. These findings suggest that B16-CM increased the endothelial permeability irreversibly without the decrease of F-actin, and that soluble factor(s) which were secreted from the tumor cells participate in the construction of the hyperpermeable structure of tumor vessels in vivo.

Isolation and properties of tumor-derived endothelial cells from rat KMT-17 fibrosarcoma

Rat KMT-17 fibrosarcoma-derived endothelial cells were isolated by Percoll gradient centrifugation with an attaching-speed separation technique, and their properties in culture were examined. The primary cultured tumor-derived endothelial cells (TEC) showed angiotensin-converting enzyme activity, positivity for Factor VIII-related antigen staining, and typical capillary-like formation on Matrigel. The primary cultured TEC monolayer showed greater permeability than normal tissue-derived endothelial cell (aorta, vena cava and epididymal fat capillary) monolayers on FITC-dextran diffusion (molecular weight 70,000). Leukocyte adhesion to TEC was reduced compared to that to fat-derived capillary endothelial cells. These characteristics resembled those of tumor vascular endothelium, and were observed both in the primary and first-passage cell cultures, but not in the fourth-passage cell cultures. Our findings indicate that primary or subcultured TEC are applicable for studies of the physiological characteristics of tumor endothelial cells.

Synergistic actions of stem cell factor and other burst-promoting activities on proliferation of CD34+ highly purified blood progenitors expressing HLA-DR or different levels of c-kit protein

We studied the synergistic effects of stem cell factor (SCF) and other burst-promoting activities (BPAs) such as interleukin-3 (IL-3), granulocyte-macrophage colony-stimulating factor (GM-CSF), or IL-9 on proliferation of human peripheral blood-derived highly purified progenitors. SCF, IL-3, GM-CSF, and IL-9 showed significant BPA when CD34+HLA-DR+ cells were used as the target population. IL-3 exerted the most potent BPA, and GM-CSF supported approximately 40% to 70% of the erythroid burst-forming units that are responsive to IL-3. SCF and IL-9 showed much weaker BPA than that of IL-3 or GM-CSF. Combinations of IL-3 with other BPAs did not show synergistic actions supporting erythroid-burst formation. However, GM-CSF showed a significant additive effect with IL-9 or SCF. When CD34+c-kithigh cells were used as the target, SCF showed a much stronger BPA. Also, a distinct additive effect between SCF and IL-3 or GM-CSF on erythrocyte-containing mixed colony formation was observed. On the other hand, when CD34+c-kitlow cells were used as the target, SCF, IL-3, and GM-CSF could express BPA. In contrast, IL-9 alone failed to support erythroid-burst formation. Because CD34+c-kithigh cells weakly expressed CD34 antigen, these cells appeared to be more mature progenitors than CD34+c-kitlow cells. These results suggest that IL-9 acts on more mature progenitors than those of SCF, IL-3, or GM-CSF and that the primary target of SCF is multipotential progenitors at the very early stage of development.

Functional morphology of lesions of psoriasis vulgaris transplanted into nude mice at an early stage

We examined the growth and differentiation of transplanted psoriatic skin in nude mice at an early stage. Psoriatic lesions from three patients were biopsied. Each biopsied specimen was cut into five blocks, which were individually transplanted to nude mice by the embedding method. Two weeks later, growth and differentiation of transplanted specimens were examined by bromodeoxyuridine (BrdU) labelling method and by electron microscopy. Electron microscopically, basal cells were longitudinally high, and the cellular processes were elongated. Basal laminae were multilayered. In the cytoplasm of the basal cells, many mitochondria, endoplasmic reticula, and ribosomes were seen, and tonofibrillar formation was poor. In cell groups in the upper parts of these lesions, both nuclei and cytoplasm showed degeneration. Psoriatic skin transplanted to nude mice exhibited newly formed psoriatic skin and initial epidermal necrosis. The BrdU labelling method labelled cells scattered in the lower part of the epidermis. Psoriatic skin transplanted to nude mice resembled that before transplantation in both ultrastructural findings and growth pattern.

Intravenous administration of polyethylene glycol-modified tumor necrosis factor-alpha completely regressed solid tumor in Meth-A murine sarcoma model

Complete regression of solid tumors was achieved by plural intravenous (i.v.) administrations of polyethylene glycol (PEG)-modified tumor necrosis factor-alpha (TNF-alpha), prepared by covalently modifying natural human TNF-alpha with N-succinimidyl succinate PEG. The anti-tumor efficacy of PEG-modified TNF-alpha (MPEG-TNF-alpha), in which 56% of the TNF-alpha-lysine residues were coupled with PEG, was compared with that of native TNF-alpha in the Meth-A murine fibrosarcoma model. MPEG-TNF-alpha and native TNF-alpha were given as i.v. injections twice a week for 2 weeks. The anti-tumor activity of MPEG-TNF-alpha was dose-dependent and was far superior to that of native TNF-alpha. Complete regression was observed in 3 of the 8 mice administered native TNF-alpha at the dose of 10,000 JRU (Japan reference unit), but 4 of the 5 remaining mice died during the therapeutic period. At 5,000 JRU of native TNF-alpha, no case of complete regression was observed. By contrast, complete regression was obtained in all 10 mice given 200 JRU of MPEG-TNF-alpha. No side-effects were observed at the dose of 500 JRU of MPEG-TNF-alpha, which was 2.5 times the minimal dose (200 JRU) of MPEG-TNF-alpha required for complete regression in all treated mice. MPEG-TNF-alpha appears to have potential as a candidate anti-tumor therapeutic agent.

Expression of hepatocyte growth factor in normal and carbon tetrachloride-treated monkeys

We examined hepatocyte growth factor-producing organs in normal and carbon tetrachloride-treated Japanese monkeys, a species more related to human beings than rats, by measuring hepatocyte growth factor protein and hepatocyte growth factor mRNA in various tissues. Hepatocyte growth factor protein and hepatocyte growth factor mRNA levels were determined by use of an enzyme-linked immunosorbent assay for human hepatocyte growth factor and Northern-blot analysis using human hepatocyte growth factor cDNA as a probe, respectively. Although very slight amounts of hepatocyte growth factor protein were found in various organs of normal monkeys, the hepatocyte growth factor protein levels were remarkably increased only in the livers and spleens of carbon tetrachloride-treated monkeys. Hepatocyte growth factor mRNA was distinctly detected in the livers, spleens, lungs, intestinal tracts, adrenal glands and aortas of normal monkeys. After the administration of carbon tetrachloride, the hepatocyte growth factor mRNA levels in the liver, spleen and gastrointestinal tract were markedly increased; the level in the lung was unchanged, differing from the findings in rats; and the levels in adrenal gland and aorta were unaltered. These results indicate that the liver is an important hepatocyte growth factor-producing organ in monkeys during liver regeneration and that hepatocyte growth factor induced in the liver may stimulate hepatocyte proliferation by way of a paracrine mode.

A longitudinal study from prepuberty to puberty of gingivitis. Correlation between the occurrence of Prevotella intermedia and sex hormones

A longitudinal study of 24 subjects progressing normally from prepuberty to puberty was undertaken to evaluate the effects of sex hormone levels on clinical and microbiologic parameters and on serum antibodies. During elementary school, at the beginning of the longitudinal monitoring, 2 groups, 12 subjects with gingivitis and 12 gingivitis-free subjects, were selected and observed through puberty. Bone ages and self-assessment of secondary sex characteristics were used to confirm puberty. A statistically significant increase in the proportions of Prevotella intermedia including Prevotella nigrescens and serum antibody levels against P. intermedia was seen in gingivitis group throughout the longitudinal study. Serum levels of testosterone in boys and estradiol and progesterone in girls was positively correlated with levels of P. intermedia and P. nigrescens. In puberty, a slight but significant increase in GI scores over prepuberty has been shown; however, there was no significant change in PlI from prepuberty to puberty. Our study confirmed that there was a statistically significant increase in gingival inflammation and in the proportion of P. intermedia and P. nigrescens in puberty relative to the baseline value, except in the gingivitis-free male group. Our findings suggest that these increases are correlated with elevation in systemic levels of the sex hormones.

[Single-dose toxicity study and twenty-eight-days intravenously repeated dose toxicity study of desethyl-piperacillin in rats]

Desethyl-piperacillin (desethyl-PIPC) is an active metabolite of PIPC which was newly found in clinical field. We carried out a single intravenous toxicity study at the dosage of 2000 mg/kg, and 28-days intravenous toxi-city study at the daily dosage of 400 mg/kg followed by 28-days recovery study using both sexes of rats. The following results were obtained. In the single dose toxicity study, no deaths occurred in rats injected 2000 mg/kg of desethyl-PIPC, therefore it is presumed that minimal lethal dose of desethyl-PIPC is over 2000 mg/kg in both sexes. As clinical signs, decrease in locomotor activity, deep breath and loose stool were observed. In the patho-logical study, dilatation of cecal lumen was observed macroscopically, but no significant changes were observed histologically. In the repeated dose toxicity study, loose stool, increase in water consumption, dilatation of cecal lumen and increase in its weight were noted. These abnormal findings were considered to be due to antimicrobial activity of desethyl-PIPC. In addition, decrease in the ratio of serum gamma-globulin and increase in the ratio of alpha 1-globulin were observed, but A/G ratio was not affected. After withdrawal of desethyl-PIPC administration, these abnormal findings tended to disappear. As mentioned above, the minimal lethal dose of desethyl-PIPC is over 2000 mg/kg in the single dose toxicity study and abnormal signs were slight in the repeated dose toxicity study at the dosage of 400 mg/kg of desethyl-PIPC for 28 days in rats. It is, therefore, concluded that desethyl-PIPC is a low toxic metabolite of PIPC.

Construction from a single parent of baker's yeast strains with high freeze tolerance and fermentative activity in both lean and sweet doughs

From a freeze-tolerant baker's yeast (Saccharomyces cerevisiae), 2,333 spore clones were obtained. To improve the leavening ability in lean dough of the parent strain, we selected 555 of the high-maltose-fermentative spore clones by using a method in which a soft agar solution containing maltose and bromocresol purple was overlaid on yeast colonies. By measuring the gassing power in the dough, we selected 66 spore clones with a good leavening ability in lean dough and a total of 694 hybrids were constructed by crossing them. Among these hybrids, we obtained 50 novel freeze-tolerant strains with good leavening ability in all lean, regular, and sweet doughs comparable to that of commercial baker's yeast. Hybrids with improved leavening ability or freeze tolerance compared with the parent yeast and commercial baker's yeasts were also obtained. These results suggest that hybridization between spore clones derived from a single parent strain is effective for improving the properties of baker's yeasts.

Morphology and synaptic connections of slowly adapting periodontal afferent terminals in the trigeminal subnuclei principalis and oralis of the cat

Previous studies suggest that sensory information from primary afferent fibers is processed in a distinct manner in the individual subnuclei of trigeminal sensory nuclear complex. The present study has addressed this issue by using intra-axonal labeling with horseradish peroxidase to examine the ultrastructure and synaptic organization of axon terminals from slowly adapting (SA) periodontal afferents in the ventral subdivision (Vpv) of principalis and the rostro-dorsomedial part (Vo.r) of oralis. Our observations are based on complete or near-complete reconstructions of 139 synaptic boutons in Vpv and 105 in Vo.r. All the labeled boutons contained clear, spherical, synaptic vesicles and were presynaptic to unlabeled dendrites, and they were frequently postsynaptic to unlabeled axon terminals containing pleomorphic synaptic vesicles (P-endings). The P-endings frequently formed axodendritic synapses on dendrites which received axodendritic synapses from labeled boutons (synaptic triads). On the basis of the number of contacts, synaptic arrangements associated with the labeled boutons could be subgrouped into simple (one or two contacts), intermediate (three or four contacts), and complex (five or more contacts) types. The labeled boutons varied from round to elongated forms with smooth to more irregular or scalloped contours. The boutons with scalloped contour were much more frequent in the complex type. The boutons of the intermediate type were significantly smaller than the complex type and larger than the simple type. The SA periodontal afferent terminals participated in each type of synaptic arrangements in Vpv, but were mostly of the simple type in Vo.r. The size of labeled boutons was significantly larger in Vpv than in Vo.r. The total number of axodendritic and axoaxonic contacts per labeled bouton was significantly higher in Vpv than in Vo.r. Another difference was the more frequent occurrence of synaptic triads in Vpv than in Vo.r. These observations provide evidence that sensory information from primary afferent fibers is processed in a different manner in the two subnuclei.

Insulin treatment in Japan

The therapeutic methods of treating Japanese cases of diabetes with insulin have been developed following the lead of the USA and European countries. With support from the National Health Care System, most clinics have been able to provide relatively good care of diabetic patients under treatment, but judging from the increase in the number of patients with chronic diabetic complications, the development of better methods of treatment and their wider application is a matter of great urgency.

A comparison of drug transport through cultured monolayers of bovine brain capillary and bovine aortic endothelial cells

To examine how efficient primary cultured brain capillary endothelial cells are as an in vitro blood-brain barrier (BBB) system with regard to drug transport, we compared bovine brain capillary endothelial cells (BBCEC) with bovine aortic endothelial cells (BAEC). Paracellular and transcellular transport were examined. [14C]Sucrose and fluorescein isothiocyanate-dextran (FITC-dextran)(average molecular weight about 4400 and 71200) were used as indices of paracellular transport. The permeability coefficients of [14C]sucrose and FITC-dextran through BBCEC monolayers were about 3 and 30-40 fold lower than those through BAEC monolayers, respectively. Transcellular transport was examined by means of [3H]leucine and [3H]alanine uptake studies. The Km value (Michaelis constant) of the amino acid uptake was lower in BBCEC than in BAEC. BBCEC had higher alkaline phosphatase (ALP) and gamma-glutamyl transpeptidase (gamma-GTP) activity than BAEC when cultured in vitro. These results suggest that BBCEC are suitable for drug transport studies across the BBB in vitro.

Phenotypic characteristics of bone marrow cells in patients with rheumatoid arthritis

OBJECTIVE

Our previous study showed the presence of abnormal myeloid lineage cells in the epiphyseal bone marrow adjacent to joints affected with severe rheumatoid arthritis (RA). Now, we investigated whether there were any changes of other marrow cell populations related to RA, and whether there were any pathologically characteristic changes in the iliac bone marrow, which is one of the major systemic hematopoietic organs.

METHODS

2-Color flow cytometry was carried out to analyze the phenotypes of mononuclear cells (MNC) fractions in bone marrow aspirates and venous blood from 56 patients with RA and 7 non-RA controls.

RESULTS

The absolute number of MNC in the iliac bone marrow was increased by 3-fold in the RA patients compared with the non-RA controls. In contrast, no significant increase of MNC was observed in the tibial epiphyseal bone marrow or peripheral blood. The ratio of each MNC fraction in the iliac bone marrow did not differ significantly between the RA patients and the non-RA controls. In lymphocyte subsets, the percentage of HLA-DR+CD8+ cells to all CD8 cells in the iliac bone marrow increased significantly in the RA patients compared with the non-RA controls. Abnormal myeloid cells (MX-GA+MY4+ cells), specific to severe RA, were found to be more concentrated in the iliac bone marrow than in the tibial epiphyseal bone marrow.

CONCLUSION

Characteristic pathologic changes of the iliac bone marrow suggest an important role of systemic bone marrow in the progression of RA.

NADPH diaphorase neurones are evenly distributed throughout cat neocortex irrespective of functional specialization of each region

Using NADPH diaphorase histochemistry as a marker for nitric oxide synthase we investigated the possible sites of nitric oxide synthesis in cat cerebral neocortex. Intensely stained neurones were found mainly in the deep layers of the neocortex and underlying medulla. Virtually all neurones in the cerebral medulla were NADPH diaphorase positive. The density of diaphorase neurones was estimated in the cortex/medulla border zones of each neocortical gyrus. Diaphorase neurones were evenly distributed throughout the neocortex and no significant statistical difference between gyri was observed. These findings indicate that the density of diaphorase neurones is irrespective of functional specialization of each region and are more in line with the hypothesis that NADPH diaphorase neurones are involved in the control of local cortical blood flow.