Isolation and genetic characterization of Staphylococcus aureus from wild animal feces and game meats

The populations of Japanese deer and boar have increased dramatically and have a serious impact on farming and mountain villages. Although the Japanese government promotes the use of captured wild animals, game meat is not subject to sanitary control considering that it is not subject to meat inspection or quality control. Here, we have attempted to isolate Staphylococcus aureus, a typical foodborne pathogen, as a part of an investigation of contamination in the meats of wild animals and their processing stages. We examined 390 samples of deer feces, 117 samples of wild boar feces, and 75 samples of disemboweled deer meat for isolation of S. aureus; ultimately, 30 (positive rate: 7.7%), 2 (1.7%), and 21 (28.0%) strains were isolated, respectively, from the samples. The genome sequences of these isolates were analyzed and were subjected to multilocus sequence typing. We identified 12 new sequence types (STs) and a dominant population of S. aureus with a characteristic genetic background in wild animals, namely, the ST groups derived from CC121 (number of strains = 39). These strains did not harbor the enterotoxin gene or only harbored egc-related enterotoxin, which is of low involvement in Staphylococcal food poisoning. However, one ST2449 strain, which produces causative enterotoxins, was isolated from a deer's feces. Since there are several common STs isolated from feces and dismembered meat and because fecal contamination during dismemberment is suspected, continuous monitoring and guidance for improving sanitary management conditions during processing and handling of the meat are highly warranted with immediate effect.

Development of monoclonal antibodies against Rhodococcus equi virulence-associated protein N and their application to pathological diagnosis

IMPORTANCE

Rhodococcus equi can cause infection in ruminants, and its pathogenicity is suggested to be associated with VapN. Despite its wide distribution, no immunological diagnostic method has been developed for VapN-producing R. equi. Against this background, we attempted to develop monoclonal antibodies targeting VapN and assess their application in immunostaining. In the study, mice were immunized with recombinant VapN, and cell fusion and cloning by limiting dilution permitted the generation of three antibody-producing hybridomas. The utility of the antibodies produced from the hybridomas in immunostaining was demonstrated using an infected mouse model, and the antibodies were further applied to previously reported cases of R. equi infection in goats and cattle. Although the 4H4 antibody induced the strongest reactions, the reactivity of two other antibodies was improved by antigen retrieval. Our monoclonal antibodies will be utilized to support the definitive diagnosis of suspected R. equi infection, including cases that were previously missed.

Flat and depressed lesions of the colon and rectum: Pathogenesis and clinical management

INTRODUCTION

It is not clear whether flat lesions play a role in the pathogenesis of colorectal carcinoma. Flat lesions are being increasingly recognised with new colonoscopic techniques.

MATERIALS AND METHODS

A total of 10,939 consecutive colonoscopies were performed over a 9-year period. After bowel preparation with polyethylene glycol electrolyte lavage solution, high-resolution video colonoscopy and indigocarmine spraying were performed to detect flat lesions. All lesions suggesting neoplastic change were removed by polypectomy or surgery. Cancers invading beyond the submucosal layer were excluded from this analysis. The gross appearance of flat-type lesions was classified as flat elevated type or flat depressed type based on the presence or absence of central depression.

RESULTS

A total of 5408 neoplastic lesions were index lesions, including 5035 adenomas and 373 carcinomas (124 with submucosal invasion). The prevalence of flat depressed and flat elevated lesions were 2.8% and 18.1%, respectively. Submucosal invasion rates were 17.1% in the flat depressed, 0.8% in the flat elevated, 1.6% in the sessile, 4.0% in pedunculated lesions and 9.3% in creeping lesions. The submucosal invasion rate in the flat depressed lesions was significantly higher than in any others, except for creeping lesions (P = 0.06). The percentage of flat elevated and flat depressed carcinomas among all carcinomas invading the submucosa was 6.5% and 21.0%, respectively.

CONCLUSION

Flat lesions were common during routine colonoscopy. One-quarter of colorectal cancers may be derived from flat lesions. Training in dye spray technique may result in a higher detection rate of flat colonic lesions.

Microsatellite instability in inflamed and neoplastic epithelium in ulcerative colitis

BACKGROUND

Several genetic alterations have been documented in dysplasia and cancer developing in ulcerative colitis (UC). However, the microsatellite instability (MSI) status has rarely been described, especially in the inflamed epithelium of UC.

AIMS

To study MSI status during neoplastic and inflammatory changes in UC.

METHODS

Seventy five surgically resected samples of colorectal mucosa, taken from 16 colectomy specimens of patients with UC were examined: five patients had a long duration with dysplasia or cancer (UC-LD with neoplasm), seven patients had a long duration without neoplastic changes (UC-LD without neoplasm), and four patients had a short duration without neoplastic changes (UC-SD). In addition to MSI status examined by six microsatellite markers, p53 expression was compared among the three groups.

RESULTS

With regard to non-neoplastic inflamed epithelium, MSI in two or more loci (MSI> or =2) was seen more frequently in the UC-LD without neoplasm group than in the UC-SD group (six of 14 v one of 12; p = 0.060), and significantly more often than in the UC-LD with neoplasm group (six of 14 v two of 23; p = 0.016). In the UC-LD without neoplasm group, MSI> or =2 was detected significantly more frequently in patients with severe inflammation than in those with mild inflammation (six of nine v none of five; p = 0.028). With regard to neoplastic epithelium in the UC-LD with neoplasm group, MSI in two or more loci was found in three of 17, and p53 overexpression was seen in 11 of 17 of the neoplastic lesions.

CONCLUSIONS

A high incidence of MSI in long standing UC with severe inflammation probably reflects genomic instability caused by repeated inflammatory stress. Thus, the influence of inflammation should be considered when estimating MSI in UC. It is possible that changes in p53 expression are important in the development of cancer in UC.

Brain ischemia following bilateral carotid occlusion during development of hypertension in young spontaneously hypertensive rats--importance of morphologic changes of the arteries of the circle of Willis

The present study was designed to examine the effect of morphologic changes of the arteries of the circle of Willis on cerebral blood flow (CBF) and metabolism in young spontaneously hypertensive rats (SHR). CBF in the parietal cortex was measured by the hydrogen clearance method before and during a one-hour bilateral carotid artery occlusion (BCO), and supratentorial brain metabolites were determined by standard enzymatic methods at a one-hour BCO. The internal diameters of the main arteries of the circle of Willis were estimated morphologically. With increase in age, systemic arterial pressure at rest was significantly raised, while cortical CBF tended to decrease and calculated cerebral vascular resistance increased. During BCO, CBF and supratentorial metabolism (adenosine triphosphate and lactate/pyruvate ratio) tended to be better preserved in two-month-old rats as compared with those in one- or three-month-old rats. The internal diameter of the posterior communicating artery (PcomA) was significantly smaller in the one-month-old group than in the other groups, while the diameter of the internal carotid artery was significantly smaller in rats aged three months than those in rats aged one or two months. It is indicated that cortical CBF reduction and impairment of supratentorial metabolism following occlusion of carotid arteries, at least in part, depend on the morphologic changes of the arteries of the circle of Willis associated with age and development of hypertension in young SHR.

[A case of idiopathic hemochromatosis associated with gastric cancer]

A 76-year-old male was admitted to our hospital because of general fatigue in June 1987. He had received total gastrectomy against gastric carcinoma two years previously. The examinations revealed the elevation of GOT, GPT and gamma-GTP, and increased CT number of the liver. Specimen of the liver biopsy showed deposition of iron and slight fibrosis. He was diagnosed as idiopathic hemochromatosis. He was given deferoxamine, and his elevated GOT, GPT and gamma-GTP were normalized. Idiopathic hemochromatosis is frequently associated with various malignancies including hepatic carcinoma. However, only a few cases of idiopathic hemochromatosis associated with gastric carcinoma have been reported.

Effects of acute superior cervical ganglionectomy on cerebral blood flow and metabolism in stroke-prone spontaneously hypertensive rats subjected to cerebral ischaemia

1. The effects of acute bilateral superior cervical ganglionectomy on cerebral blood flow and metabolism were investigated in stroke-prone spontaneously hypertensive rats (SHRsp), before and during cerebral ischaemia. 2. The resting cerebral blood flow was comparable between the control and denervated animals. 3. There was no significant difference in cerebral blood flow or concentration of tissue energy metabolites (adenosine triphosphate [ATP], lactate and pyruvate) between the sham-operated control and denervated animals during ischaemia. 4. The results suggest that sympathetic innervation of cerebral vessels originating from superior cervical ganglia may not play a major role in the progression of cerebral ischaemia in SHRsp.

Meningioma developed 25 years after radiation therapy for Cushing's disease

A 44-year-old woman who had been therapeutically irradiated with 45 Gy to the sellar lesion for Cushing's disease has been in remission for 25 years. A large but asymptomatic brain tumor was accidentally found in the right middle fossa by a routine follow-up computed tomography. Upon surgical removal of the tumor, the histology revealed a fibroblastic meningioma. Although the incidence of meningioma following irradiation to pituitary adenoma is rare, a follow-up computed tomography should be taken to any possible late onset, and curable complication.

Disseminated intravascular coagulation in a patient with progressive systemic sclerosis associated with necrotizing angiitis and generalized lymphadenopathy

A 47-year-old woman with progressive systemic sclerosis developed disseminated intravascular coagulation in the course of her terminal illness. She also had complicating necrotizing angiitis and generalized lymphadenopathy. The likely relationship between disseminated intravascular coagulation and vasculitis is discussed.

[A case of hepatocellular carcinoma associated with chronic renal failure on haemodialysis]

A 36 years old man with chronic renal failure on haemodialysis therapy presented with a hepatic mass which was diagnosed by ultrasonography, and was admitted to our hospital. Computer tomography and hepatic angiography revealed hepatocellular carcinoma of the right anterior superior segment of the liver. His liver function test, alpha-fetoprotein (AFP) and carcinoembryonic antigen levels in the serum were within the normal range. HBs antigen was also negative. Resection of right antero-superior segment was done following transcatheter arterial embolization. The tumor was homogeneous and light yellowish in color, and well demarcated by the capsule. Nontumorous tissue did not show either fibrosis or any inflammatory reaction. In general, hepatocellular carcinoma is associated with a positive HBs antigen and altered liver function. We here report a rare case of hepatocellular carcinoma in a man who was undergoing haemodialysis treatment for chronic renal failure with normal liver function test and negative HBs antigen.

[A case of alcoholic cirrhosis demonstrating long-term poor-visualization of the hepatic image on 99mTc-phytate scintigraphy]

A 27-year-old female patient with alcoholic cirrhosis was reported. She was admitted to the hospital because of jaundice and ascites after heavy drinking. She had a history of drinking Japanese Sake in quantities of more than 5 go/day (900 ml/day) for 7 years. On admission, she was icteric, and had both hepatosplenomegaly and ascites. Laboratory data showed an elevation of serum transaminase and bilirubin, and a decrease in the albumin and prothrombin values. A biopsy specimen of the liver showed pericellular fibrosis, fatty change, Mallory bodies and regenerative nodules, and revealed findings compatible with alcoholic cirrhosis. A 99mTc-N-pyridoxyl-5-methyltryptophan scintigram showed hepatomegaly. On the 99mTc-phytate scintigram, the uptake of radioisotope to the liver was markedly decreased with the increased uptake to the spleen and bone marrow. Even 6 months after the onset, poor visualization of the hepatic image on 99mTc-phytate scintigram continued. This is the first report of alcoholic cirrhosis demonstrating a long-term poor visualization of the hepatic image on 99mTc-phytate scintigraphy.

Effect of thromboxane synthetase inhibitor on cerebral circulation and metabolism during experimental cerebral ischemia in spontaneously hypertensive rats

The protective effect of thromboxane synthetase inhibitor, OKY-046, on brain ischemia was studied in spontaneously hypertensive rats. Cerebral ischemia was developed by bilateral carotid artery ligation (BCL) for 1 or 3 h and thereafter, circulation was restored for 15 min. OKY-046, 5 or 30 mg/kg, or saline as control was administered i.v. before BCL. Neither blood pressure nor blood gases were altered by OKY-046 or saline injection. During BCL, cerebral cortical blood flow was reduced to 25 and 15% of the resting value at 30 and 60 min, respectively, and these changes were not different among the groups. In rats with ischemia longer than 1 h, the blood flow was well preserved by OKY-046, 30 mg/kg, to 10-17% of the resting level, thus significantly higher than that (less than 5%) in non-treated rats. After 15 min recirculation, the supratentorial lactate level was lower and adenosine triphosphate (ATP) was higher in OKY-046-treated rats than in the saline-treated ischemic rats. Plasma thromboxane B2 was increased markedly in 1 h ischemic-reperfused rats without treatment and the increase was almost completely inhibited by OKY-046. In contrast, 6-keto-prostaglandin F1 alpha was increased 8.5-fold after ischemia and the increase was not affected by the treatment. OKY-046 seems to have an antiischemic effect on acutely induced cerebral ischemia. Selective inhibition of thromboxane A2 production and an inversely high level of prostaglandin I2 may be an important contribution to protection of the microcirculation during ischemia and preservation of ischemic cerebral metabolism.

Regional cerebral blood flow and metabolism in patients with transient global amnesia: a positron emission tomography study

In four patients who experienced transient global amnesia (TGA), clinical features and neuroradiological findings including positron emission tomography (PET) were studied within three months of the episodes, and compared with those in seven cases with cerebral transient ischaemic attacks (TIA). None of TGA patients had a previous history or significant risk factors for the cerebrovascular diseases. Their electroencephalogram, brain CT and angiogram for the head and neck were almost normal. PET study showed better preserved cerebral blood flow and oxygen metabolism in each area of the brain in patients with TGA compared with those with TIA in whom focal reductions of flow and metabolism were evident. These observations suggest that TGA is caused by reversible circulatory and/or metabolic disturbance, of which mechanism might be different from that in TIA.

Cerebrospinal fluid lactate in patients with diabetes mellitus and hypoglycaemic coma

Cerebrospinal fluid (CSF) lactate and pyruvate concentrations were determined in 20 patients with diabetes mellitus but without disturbance of consciousness and five who recovered from hypoglycaemic coma. CSF lactate was slightly but significantly higher in diabetes mellitus (1.78, SEM 0.04 m mol/l) than that in 15 control subjects (1.40, SEM 0.05 m mol/l). In those who recovered from hypoglycaemic coma, CSF lactate was markedly elevated to 2.45-4.43 m mol/l. CSF glucose concentrations, however, were substantially the same between treated hypoglycaemic and diabetes mellitus groups. These findings indicate that CSF lactate levels increase with glycaemic levels in diabetes mellitus owing to enhanced glucose influx into glycolytic pathway of the brain, and also increases in treated hypoglycaemic coma probably due to mitochondrial dysfunction or damage.

Mortality and histological findings of the brain during and after cerebral ischemia in male and female spontaneously hypertensive rats

Mortality and pathological changes of the brain during and after cerebral ischemia induced by bilateral carotid artery occlusion (BCO) were studied in male and female spontaneously hypertensive rats (SHR). Systolic arterial blood pressure at rest was significantly higher in male SHR (228 +/- 13 mm Hg, mean +/- S.E.M.) than female (192 +/- 12) (P less than 0.05). The average survival time during permanent occlusion was 11 +/- 6 h (mean +/- S.D.) in male SHR and 17 +/- 7 in female (P less than 0.005), though the cumulative mortality during 24-h ischemia was not different between male (88%) and female SHR (84%). Severe ischemic changes of nerve cells in the brain, especially in the cortex and hippocampus, were observed in 50% of male SHR at 3-h ischemia, while only 15% was observed in female SHR even after 7-h ischemia. After the temporary ischemia followed by reperfusion for 24 h, the mortality was varied between male and female SHR; 0, 31 and 100% after 1-, 3- and 5-h ischemia, respectively, in male SHR and 0% after 1- to 3-h ischemia and 33% after 5- to 7-h ischemia, respectively, in female. Ischemic changes of the brain tissue, such as acidophilic cytoplasm, nuclear degeneration and intercellular edema, were more frequent and severe in male SHR than female after recirculation following 3- or 5-h ischemia. It is concluded that the mortality and post-ischemic viability seem to be determined by the duration of ischemia and also by the degree of the neuronal damage, and female SHR is more tolerated for ischemic insult in comparison to male SHR.

Massive striatal dopamine release in acute cerebral ischemia in rats

Extracellular dopamine, 3,4-dihydroxyphenylacetic acid (DOPAC) and cerebral blood flow were simultaneously determined using in vivo brain dialysis and a hydrogen clearance method in the striatum of spontaneously hypertensive rats during ischemia and after recirculation. Massive striatal dopamine release was demonstrated in acutely induced ischemic brain.

Effect of recirculation on the recovery of cerebral metabolism after experimental cerebral ischemia in male and female spontaneously hypertensive rats

Lactate, pyruvate and adenosine triphosphate (ATP) concentrations in the brain were measured at the end of various periods of cerebral ischemia induced by bilateral carotid occlusion at 1-hour recirculation after the ischemia in spontaneously hypertensive rates (SHR). In both male and female SHR, a progressive and consistent increase in lactate and lactate/pyruvate ratio and a concomitant decrease in ATP were observed in the ischemic periods of 1, 3 or 5 h. Changes of these cerebral metabolites in females were two thirds to one half of those in males at corresponding periods of ischemia. At 1 h after recanalization of the occluded carotid arteries, metabolic derangements of the ischemic brain were little recovered in male SHR exposed to only 1-hour ischemia, whereas in female SHR the decreased ATP levels were recovered close to the nonischemic control level even after 7-hour ischemia. Furthermore, the increased lactate in female was attenuated to only one sixth of that in male at 1-hour recirculation after 5-hour ischemia. It is concluded that the recovery of the cerebral ischemic metabolism by reperfusion is better in female than male SHR, probably because of the smaller metabolic changes during the ischemic insult, and the fact that the degree as well as the duration of ischemia seem to be important factors for sufficient recovery from ischemic impairment of the brain.

Role of adrenal catecholamines in cerebrovasodilation evoked from brain stem

We studied whether adrenal medullary catecholamines (CAs) contribute to the metabolically linked increase in regional cerebral blood flow (rCBF) elicited by electrical stimulation of the dorsal medullary reticular formation (DMRF). Rats were anesthetized (alpha-chloralose, 30 mg/kg), paralyzed, and artificially ventilated. The DMRF was electrically stimulated with intermittent trains of pulses through microelectrodes stereotaxically implanted. Blood gases were controlled and, during stimulation, arterial pressure was maintained within the autoregulated range for rCBF. rCBF and blood-brain barrier (BBB) permeability were determined in homogenates of brain regions by using [14C]iodoantipyrine and alpha-aminoisobutyric acid (AIB), respectively, as tracers. Plasma CAs (epinephrine and norepinephrine) were measured radioenzymatically. DMRF stimulation increased rCBF throughout the brain (n = 5; P less than 0.01, analysis of variance) and elevated plasma CAs substantially (n = 4). Acute bilateral adrenalectomy abolished the increase in plasma epinephrine (n = 4), reduced the increases in flow (n = 6) in cerebral cortex (P less than 0.05), and abolished them elsewhere in brain (P greater than 0.05). Comparable effects on rCBF were obtained by selective adrenal demedullation (n = 7) or pretreatment with propranolol (1.5 mg/kg iv) (n = 5). DMRF stimulation did not increase the permeability of the BBB to AIB (n = 5). We conclude that the increases in rCBF elicited from the DMRF has two components, one dependent on, and the other independent of CAs. Since the BBB is impermeable to CAs and DMRF stimulation fails to open the BBB, the results suggest that DMRF stimulation allows, through a mechanism not yet determined, circulating CAs to act on brain and affect brain function.

Cerebrospinal fluid lactate in patients with hepatic encephalopathy

Cerebrospinal fluid (CSF) lactate and pyruvate concentrations were determined in 16 patients with hepatic encephalopathy before and/or after treatment. CSF lactate was significantly increased to 1.92 +/- 0.11 mmol/l in hepatic encephalopathy before the treatment in comparison to 1.40 +/- 0.05 mmol/l in control subjects. In 9 of 11 patients with moderate or stage 2 encephalopathy, CSF lactate levels were below 2 mmol/l. In contrast, in 4 of 5 patients with stage 3-4 encephalopathy, CSF lactate levels were higher than 2 mmol/l. CSF lactate was decreased with the recovery of neurological symptoms by the treatment. These findings indicate that CSF lactate levels reflect the severity of metabolic impairment of the brain. Hypocapnia was frequently observed in these encephalopathic patients, and arterial PCO2 correlated inversely with CSF lactate and linearly with CSF HCO3-, suggesting that CSF lactic acidosis contributes to hyperventilation in hepatic encephalopathy. It is concluded from present results that metabolic disorder of neuronal cells might be one of the important factors for the development of hepatic encephalopathy.

Lesions of nucleus tractus solitarii globally impair cerebrovascular autoregulation

We studied the effects of acute bilateral electrolytic lesions of the nucleus tractus solitarii (NTS) on regional cerebral blood flow (rCBF) and its autoregulation in rats anesthetized (alpha-chloralose, 40 mg/kg), paralyzed (tubocurarine), and artificially ventilated. rCBF or regional cerebral glucose utilization (rCGU) was measured 30 min after NTS lesions, by the 14C-iodoantipyrine technique or 2-deoxyglucose method, respectively. Cerebrovascular autoregulation was assessed in groups of 4-5 rats at three levels of arterial pressure (AP): 90, 125, and 140 mmHg. AP was lowered by hemorrhage or elevated by intravenous infusion of phenylephrine. NTS lesions did not alter rCBF at 125 mmHg (P greater than 0.05) but resulted in loss of autoregulation (P less than 0.05, analysis of variance). In contrast, lesions of the cuneate nucleus or transection of the baroreceptor afferents did not alter autoregulation. NTS lesions did not affect the reactivity of the cerebrovascular bed to hypercarbia (PaCO2 57.4 +/- 1; n = 5) or hypocarbia (PaCO2 24.4 +/- 1; n = 5) nor the rCGU in any brain regions (P greater than 0.05; n = 5). We conclude that lesions of the NTS impair cerebrovascular autoregulation. The effect is not due to changes in metabolism, nonspecific effects of the lesions, vasoparalysis, or interruption of the baroreceptor reflex arch. Neural pathways originating in or passing through the NTS can regulate the cerebrovascular autoregulation of the entire brain.

Effects of intravenous glycerol on cerebral blood flow and tissue metabolism in acute cerebral ischemia in spontaneously hypertensive rats

The effects of antiedematous agent with intravenous 10% glycerol on cerebral blood flow (CBF) and metabolism were studied in acute cerebral ischemia experimentally induced by bilateral carotid artery occlusion in spontaneously hypertensive rats (SHR). CBF was measured by the hydrogen clearance technique and brain tissue metabolites such as lactate, pyruvate and ATP in the ischemic brain frozen in situ were determined by the enzymatic method. In comparison with saline-infused SHR, the reduction of CBF in the thalamus following carotid occlusion was significantly small in the glycerol treated SHR. Supratentorial ATP concentration in the 3 hr-ischemic brain was reduced in both groups of rats, but its reduction was significantly smaller in the glycerol-infused group than the other. Lactate and lactate/pyruvate ratio tended to be less increased in the glycerol rats, indicating that ischemic metabolism was restrained by the treatment. The present results strongly suggest that intravenous glycerol is effective against acute cerebral ischemia from the view point of cerebral hemodynamic and metabolism.

Effects of hematocrit on brain metabolism in experimentally induced cerebral ischemia in spontaneously hypertensive rats (SHR)

Brain tissue lactate, pyruvate, and adenosine triphosphate (ATP) were measured 60 min after bilateral carotid ligation in spontaneously hypertensive rats, of which hematocrit (HCT) was varied by exchanging with isovolemic homologous red cells, plasma or whole blood. Supratentorial lactate of the ischemic brain was increased more in high HCT (greater than or equal to 50%) and less in low HCT (30-39%) compared with normal HCT (40-49%). In very low HCT (less than 30%), however, lactate was increased to further extent compared with any other group of HCT (ANOVA p less than 0.0001). Lactate/pyruvate (L/P) ratio of the ischemic brain showed similar changes, namely U-shaped correlation to HCT. In contrast, supratentorial ATP was decreased more markedly in very low HCT, followed by high and normal HCT, and minimally decreased in low HCT, demonstrating an inverse U-shaped relationship to HCT. Mean arterial pressure and arterial acid-base parameters in ischemic animals did not differ among HCT groups. There were no HCT-related changes of brain metabolites in non-ischemic control rats. These findings indicate that cerebral ischemia following carotid ligation is more severe in high HCT but less in low HCT, probably due to hemodynamic effects of HCT changes. When HCT is reduced to below 30%, however, insufficient oxygen supply to the brain or anemic hypoxia may superimpose on ischemia, resulting in more markedly impairment of brain metabolism. The role of HCT as a cause of cerebral ischemia and its severity is discussed.

Intrinsic gamma-aminobutyric acid neurons in the nucleus of the solitary tract and the rostral ventrolateral medulla of the rat: an immunocytochemical and biochemical study

Sympathoexcitatory neurons in the C1 adrenergic area of the rostral ventrolateral medulla (RVL) are tonically inhibited by gamma-aminobutyric acid (GABA). To identify the source of this GABAergic input, the distribution of neurons containing glutamate decarboxylase (GAD) was determined immunocytochemically in rats treated with colchicine. Numerous GAD-stained neurons were located in the nucleus of the solitary tract (NTS) and in RVL. Unilateral lesions in NTS did not alter GABA content or GAD activity in RVL, indicating that the afferent projection from NTS to RVL is not GABAergic. Intrinsic GABAergic neurons in RVL may provide tonic inhibition of vasomotor neurons in the C1 area.

Pulmonary hemorrhage in experimental cerebral ischemia in mongolian gerbils. Brain metabolism and lung pathology

Pulmonary changes in acute cerebral ischemia were studied in anesthetized Mongolian gerbils, in which both carotid arteries were occluded simultaneously. Lactate, pyruvate and adenosine triphosphate (ATP) in the brain were measured as indicators of the severity of cerebral ischemia. Microscopic changes in the lung were arbitrarily scored from 0 (normal) to 3 points (severely affected) by the grade and the extent of lesions. Mean arterial pressure (MAP) was also measured through the cannulated femoral artery before and after carotid artery occlusion in a separate group of animals. Cerebral lactate was increased while ATP decreased in ischemic animals in which pulmonary changes such as intra-alveolar hemorrhages were prominent and frequent. The lung pathology score averaged 1.3 in animals with severe ischemia (lactate greater than or equal to 10 mM/Kg), 0.7 in moderate ischemia (5-10 mM/Kg) and 0.3 in mild or no ischemia (less than 5 mM/Kg), respectively, suggesting that severe brain ischemia may cause fulminant pulmonary changes. The mechanism of pulmonary lesions in acute cerebral ischemia is discussed.

[Protective effects of 4-(o-benzylphenoxy)-N-methylbutylamine hydrochloride (bifemelane) on acutely induced cerebral ischemia in Mongolian gerbils and spontaneously hypertensive rats (SHR)]

Effects of new antihypoxic agent (bifemelane) on survival and brain metabolism were studied in acute cerebral ischemia induced by bilateral carotid artery ligation in mongolian gerbils and SHR. Either 10 mg/kg or 30 mg/kg body weight of bifemelane solved in distilled water was intraperitoneally administered 1 hr in gerbils and 1.5 hrs in SHR prior to carotid ligation, and same amount of vehicle was also given in similar manner for control animals. Brain tissue metabolites such as lactate, pyruvate and ATP were determined by using the enzymatic technique in the ischemic brain frozen in situ 1 hr after carotid ligations in SHR. Mean survival times following carotid ligations were 186 +/- 255 min (+/- SD) in control gerbils, 429 +/- 455 min in those with 10 mg/kg of bifemelane, and 310 +/- 429 min in those with 30 mg/kg respectively, its difference between control and 10 mg/kg group being significant (P less than 0.05). Supratentorial lactate concentrations in the ischemic brains of SHR were substantially the same among the groups, whereas ATP levels were 0.62 +/- 0.24 mM/kg in control animals, 1.10 +/- 0.67 mM/kg in rats with 10 mg/kg of the drug, and 1.13 +/- 0.42 mM/kg in those with 30 mg/kg, respectively. In animals with a high dose pretreatment, the reduction of ATP was significantly smaller than that in control (P less than 0.02), indicating that this agent prevents a decline of high energy phosphate in the ischemic brain although anaerobic metabolites increase similarly in animals of all experiment groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebrospinal fluid lactate and pyruvate concentrations in patients with malignant hypertension

Lactate and pyruvate concentrations and acid-base parameters in cerebrospinal fluid (CSF) and arterial blood were measured in 21 patients with malignant hypertension ( MHT ), 19 with benign hypertension (BHT) and 21 normotensive subjects (NT). Average values for CSF lactate and lactate/pyruvate (L/P) ratio were significantly higher in MHT (1.90 +/- 10 mM/1, 19.2 +/- 1.0) than in either BHT (1.50 +/- 0.05 mM/l, 15.7 +/- 0.7) or NT (1.44 +/- 0.04 mM/1, 15.7 +/- 0.4). There was a linear correlation between CSF lactate and CSF pressure (r = 0.565, P less than 0.01), and the latter was also related to mean arterial pressure exceeding 150 mm Hg (r = 0.553, P less than 0.01). Such increases in the acid metabolites in CSF indicate that brain metabolism becomes anaerobic in MHT , probably due to increased intracranial pressure. Increased cerebrovascular permeability is also discussed as participating in causal mechanisms.

Sex difference of barbiturate-protection in experimental cerebral ischemia in spontaneously hypertensive rats (SHR)

Survival time following bilateral carotid occlusion was significantly longer in spontaneously hypertensive rats (SHR) anesthetized with barbiturate than in those with ether. Under barbiturate anesthesia, female SHR survived longer (16.6 h) than did males (10.9 h), whereas such sex difference was not found in those with ether anesthesia. The present results indicate sex difference of barbiturate-protection in cerebral ischemia.

Effects of hyperventilation on cerebral blood flow and brain tissue metabolism in normotensive and spontaneously hypertensive rats

Cerebral vascular carbon dioxide (CO2) reactivities were compared in normotensive (NTR) and hypertensive (SHR) rats. Cerebral blood flow (CBF) in cortex and thalamus were evaluated before and during one hour of hyperventilation. After one hour of hyperventilation brain lactate, pyruvate, and ATP concentrations were also determined. Significant and similar reductions of CBF due to hyperventilation induce hypocapnia were found in both NTR and SHR groups. In contrast the percent increase in cerebrovascular resistance (CVR) per unit decrease in paCO2 was significant, indicating that hypocapnia induced vasoconstriction is greater in NTR than in SHR groups. During hyperventilation the average value for lactate in the NTR group was 3.98 mM/kg. In contrast it was 3.15 mM/kg in the SHR group, a significant difference (p less than 0.05). When paCO2 fell below 15 mm Hg the cerebral lactate increased strikingly in the NTR group and cortical CVR was reduced suggesting that an accumulation of the ischemic metabolites caused dilatation of the constricted cerebral vessels. In contrast the SHR group disclosed no such changes. The increase CVR characteristic of SHR appeared to diminish the cerebral vasoconstrictive response to hypocapnia. As a result ischemic metabolites in the brain do not increase in this group to the degree that they do in NTR.

Stroke-prone spontaneously hypertensive rats as an experimental model of malignant hypertension. A pathological study

A light-microscopic study of various organs of stroke-prone spontaneously hypertensive (SHRSP) rats was performed. The rats characteristically developed fibrinoid necrosis of the wall and marked cellular thickening of the intima and media of the arterioles and small arteries of the kidney, testicle, mesentery, adrenal gland, brain, etc. Parenchymal damage of the organs, secondary to the vascular alterations took place. There were no accumulations of lipids in the vascular lesions. Though stroke has been stressed as a characteristic clinical feature of the SHRSP rats, the cerebral lesions are different from those seen in ordinary cerebrovascular disease. Furthermore, many organs are involved. The overall vascular changes in the brain and other organs are consistent with those seen in malignant hypertension; the SHRSP rat is an excellent model of this disease.

Changes in local cerebral blood flow following bilateral carotid occlusion in spontaneously hypertensive and normotensive rats

Local blood flow in the cortex and thalamus was measured by the hydrogen clearance method in spontaneously hypertensive rats (SHR) and normotensive rats (NTR) before and after bilateral carotid occlusion. There were no differences in the resting blood flow values between SHR and NTR. Following carotid occlusion cortical blood flow in SHR was markedly reduced to 17% of the resting level at 1 h and, further, to less than 10% at 3--5 h period, while in NTR it decreased only to 36--38% during 5 h occlusion. Thalamic blood flow in SHR was decreased to 39% at 1 hr and to below 20% at 3--5 h, while in NTR it remained approximately 40% of the resting level during 5 h occlusion. The blood flow reduction in either cortex or thalamus after carotid occlusion was much greater in SHR than in NTR. This difference was highly significant. The increased cerebral vascular resistance caused by persistent hypertension may play an important role in a greater reduction of blood flow in SHR after carotid occlusion. Relation of the blood flow reduction to the brain metabolism is discussed.

Effects of arterial hypotension on brain metabolism in normotensive and spontaneously hypertensive rats

The effects of graded systemic hypotension induced by the combination of bleeding and trimethaphan camsylate infusion on brain metabolism were studied in normotensive rats (NTR) and spontaneously hypertensive rats (SHR). Metabolites such as lactate, pyruvate and adenosine triphosphate (ATP) of the brain frozen in situ were measured at the end of 1 hour of hypotension. In SHR, either cerebral lactate or the lactate/pyruvate (L/P) ratio increased rapidly and progressively with a concomitant decrease in ATP, when mean arterial blood pressure (MAP) fell below about 50 mm Hg. In NTR, on the other hand, the metabolites changed little until MAP fell to about 40 mm Hg. Metabolic derangements of the brain during profound hypotension were more marked and severe in SHR than in NTR. These results suggest that the SHR is more vulnerable to severe hypotension than NTR, probably due to hemodynamic difference of the cerebral circulation between the 2 groups. The increased cerebral vascular resistance and upward shift of cerebral autoregulation in hypertension might be responsible for this vulnerability.

Vascular changes underlying cerebral lesions in stroke-prone spontaneously hypertensive rats. A serial section study

The relationship of the vascular changes to the cerebral lesions has been studied using serial sections of the brains from five cases of the stroke-prone spontaneously hypertensive rats. Infarction was observed in a form of microinfarct related to single or plural occluded arterioles in the brain and subarachnoid space. Though most arterioles with fibrinoid necrosis of the wall were occluded with thrombus, infarct, which was obviously related to the occluded arterioles, was verified only in a few occasions. It was proved that infarction did not develop in all the areas irrigated by the occluded arterioles, and the regional circulation was assumed to have been maintained by the collateral circulation. There was rarefaction of the neutrophil with preservation of the neurons in the cortex around the vascular changes, such as fibrinoid necrosis of the wall. Widespread rarefaction and cyst formation were observed in the subjacent white matter, which were more marked in the vicinity of the vascular changes in the cortex. These histological changes were interpreted to be the tissue degeneration secondary to edema.

Experimental cerebral ischemia in spontaneously hypertensive rats (SHR): Importance of degree of hypertension

To study the relationship between the degree of hypertension and experimentally-induced cerebral ischemia, brain metabolites, including lactate, pyruvate and adenosine triphosphate (ATP) were determined one hour after bilateral carotid occlusion in 119 spontaneously hypertensive rats (SHR) with a variety of mean arterial pressures (MAP). Of these, 36 SHR were given antihypertensive agents for 10 weeks to reduce blood pressure prior to the experiment. There was a significant linear correlation between MAP before and either supratentorial lactate (r = 0.482, p less than 0.001) or the lactate/pyruvate ratio (r = 0.388, p less than 0.001) in the brain after carotid occlusion. An inverse correlation was observed between supratentorial lactate and either ATP (r = -0.627, p less than 0.001) or arterial PCO2 (r = -0.477, p less than 0.001) after carotid occlusion. The changes suggest that the animals with a higher MAP had a greater increase in ischemic metabolites with a decrease in ATP and a more pronounced hypocapnia after carotid occlusion. This hypocapnia is believed to be due to hyperventilation induced by cerebral ischemia. It is concluded that hypertensive rats are more susceptible to cerebral ischemia and the susceptibility is related to the degree of hypertension. By long-term lowering of the blood pressure prior to carotid occlusion, the ischemic changes are lessened in this experimental model.

Response of cortical and pial arteries to changes of arterial CO2 tension in rats--a morphometric study

Changes of the internal (d) and external diameter (D) of cerebral arteries in response to the various levels of arterial pCO2 were studied in anesthetized rats, of which brains were frozen in situ with isopentane cooled in liquid nitrogen. The parietal cortex was fixed with osmium tetroxide and stained with toluidine blue for morphometry of the cerebral arteries. In comparison with control animals (pCO2 = 41.2 mm Hg), the d/D ratio in animals with hypercapnia (pCO2 = 69.9 mm Hg) was increased by 11.7% in the pial arteries and 7.9% in the cortical arteries, indicating vasodilatation. In contrast, the d/D ratio in those with hypocapnia (pCO2 = 27.7 mm Hg) was decreased by 6.2% and 13.0%, respectively, indicating vasoconstriction. There was a significant linear correlation existing between the d/D ratio of either pial or cortical arteries and pCO2. It is concluded that the cortical arteries respond to changes of arterial pCO2 in a similar manner to the pial arteries.

Stroke-prone spontaneously hypertensive rats as an experimental model of malignant hypertension. I. A light- and electron-microscopic study of the brain

A pathological study of the brain of the stroke-prone spontaneously hypertensive (SHRSP) rats revealed development of fibrinoid necrosis of the wall of the intracerebral arterioles. These arterioles were frequently accompanied by occlusion of the lumen, and occasionally intracerebral hemorrhages and mincroinfarcts. The predominant tissue alteration consisted of rarefaction and cyst formation in the white matter, and rarefaction of the neuropil and preserved neurons in the neocortex at the paramedian region of the cerebral hemispheres. Edema fluid was present in and around the lesions. The tissue degeneration can be interpreted to be the sequela of brain edema. Microinfarcts or hemorrhages are only focal lesions, and are assumed to have minor contribution to the brain swelling. Widespread expansion of the extracellular space is assumed to be responsible for the brain swelling. Overall vascular changes of the brain, kidney, and other organs were consistent with those found in malignant hypertension.

Effects of long-term antihypertensive treatment on brain metabolism after bilateral carotid artery occlusion in spontaneously hypertensive rats

The effects of antihypertensive treatment on brain metabolism after bilateral carotid occlusion were studied in spontaneously hypertensive rats. The results indicate that an increase in metabolites of ischaemic brain such as lactate and the lactate/pyruvate ratio after carotid occlusion in spontaneously hypertensive rats is apparently suppressed by treating hypertension. This suggests that hypertension may play an important role in susceptibility to cerebral ischaemia.

Influence of sex on cerebral ischemia following bilateral carotid occlusion in spontaneously hypertensive rats: a metabolic study

Cerebral lactate, pyruvate and adenosine triphosphate (ATP), and acid-base balance were measured in male and female spontaneously hypertensive rats (SHR) before, and 1, 3 and 5 hours after bilateral carotid occlusion. In male SHR, cerebral lactate and the lactate/pyruvate (L/P) ratio progressively increased after occlusion, while cerebral ATP decreased. In female SHR, an increase in lactate and the L/P ratio was less marked than in male SHR. Cerebral ATP remained unchanged 5 hours after occlusion. These data suggest that bilateral carotid artery occlusion may cause more pronounced ischemic changes in the brain in male SHR than in female SHR, resulting in a greater increase in lactate with a concomitant decrease in ATP in male SHR. Results suggest that female SHR are more resistant to cerebral ischemia following bilateral carotid occlusion than male SHR. Blood pressure and gonads in the susceptibility to cerebral ischemia are discussed.