Effects of area postrema lesion and abdominal vagotomy on interleukin-1 beta-induced norepinephrine release in the hypothalamic paraventricular nucleus region in the rat

Peripherally administered interleukin-1 beta (IL-1 beta) has been shown to increase extracellular norepinephrine (NE) concentration in the paraventricular nucleus (PVN) of the hypothalamus. The present study was carried out using an in vivo microdialysis technique in conscious rats in order to examine the possible involvement of the area postrema (AP) and the abdominal vagal afferent nerves in this effect. Extracellular NE concentrations in the PVN region were measured by high performance liquid chromatography with electrochemical detection. In AP-lesioned or abdominal-vagotomized rats, the NE increase was significantly attenuated compared to that in sham-operated rats; this reduction was greater in abdominal-vagotomized rats than in AP-lesioned rats. The results suggest that the AP as well as the abdominal vagal afferent nerves is involved in intraperitoneal (i.p.) administered IL-1 beta-induced NE release in the PVN region.

Analysis of glycosidic linkages in saccharide compounds by post-source decay fragment methods in matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy

Maltotriosyl- and panosyl-alpha-cyclodextrins and the nonaose of pullulan were analyzed by post-source decay (PSD) fragment methods of matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectroscopy. By the mass number analysis, it was found that all of the PSD fragment ions were produced by cleavages of glycosidic linkages. Comparison of the relative intensities of the ions in those compounds enabled us to distinguish two kinds of glycosidic linkages, alpha 1-4 and alpha 1-6, by MALDI-TOFMS with a new type of ion reflector: the curved field reflectron.

Masseter muscle activity during the whole day in young adults

This study was conducted to evaluate the biting function during the entire day in young adults by measuring the masseter muscle activity with a 24-hour electromyography (EMG) system. With this system, the masseter muscle activity for 24 hours was recorded in 20 male and 10 female young adult subjects with acceptable occlusion. For the male subjects, means of the number and total duration of bursts over level 2, which is one-fourth of the maximum discharge voltage during maximum clenching, were 1938 times and 357 seconds. For the female subjects, the values were 2356 times and 419 seconds. A large percentage of such high amplitude bursts as level 3 or 4 was observed during meals in both groups. These results indicated that most of the strong bursts of the masseter muscle appeared only during meals and a number of low amplitude bursts were observed during the entire day, although masseter muscle activity during the entire day in young adults was less than expected. It is anticipated that the nature of masticatory muscle activity revealed in this study might provide valuable information about the association between the biting function and the craniofacial structure or malocclusion.

Anti-gastric acid secretory mechanism of 1,6-dihydro-2-[2-(2-methylpropoxy)anilino]-6-oxo-5-pyrimidinecarboxylic acid. Effect on mucosal mast cell

To clarify the anti-gastric acid secretory mechanism of 1,6-dihydro-2-[2-(2-methylpropoxy)anilino]-6-oxo-5-pyrimidinecarbo xylic acid (CAS 98772-05-5, MAR-99), the relationship between gastric acid secretion and gastric mucosal mast cell (MMC) was studied and the effect of this compound on these parameters was examined and compared with anti-allergic drugs (mast cell stabilizers) and anti-ulcer drugs. The release of histamine from MMC cultured from bone marrow and connective tissue mast cell (CTMC) isolated from peritoneal cavity was found to be induced by the addition of ethanol (final conc. 17.5%), and the inhibitory effect on histamine release from MMC is closely associated with the anti-gastric secretory effect. That is to say, MAR-99 (10(-9)-10(-7) mol/l) inhibited histamine release from MMC induced by ethanol in a concentration-dependent manner. The action of MAR-99 on MMC was more sensitive than that of CTMC. In addition, MAR-99 (100 mg/kg i.d.) suppressed gastric acid secretion. On the other hand, anti-allergic drugs (mast cell stabilizers), such as DSCG and tranilast (both 10(-7) mol/l), markedly inhibited histamine release from CTMC induced by ethanol, but these drugs (10(-8)-10(-7) mol/l) showed only a tendency to prevent the release of histamine from MMC. Furthermore these drugs (both 100 mg/ kg i.d.) had no effects on gastric acid secretion. Equally anti-ulcer drugs, such as cetraxate, teprenone and sofalcone, had no effects on histamine release from mast cells of two types and gastric acid secretion. From these results, it was suggested that MMC is closely correlated with gastric acid secretion, and the anti-gastric secretory effect of MAR-99 may mainly contribute to prevent the degranulation of MMC.

Effect of 1,6-dihydro-2[2-(2-methylpropoxy)anilino]-6-oxo-5-pyrimidineca rboxyli c acid on ethanol-induced microvascular injury in rats

To disclose the cytoprotective mechanism of 1,6-dihydro-2[2-(2-methyoxypropoxy)anilino]-6-oxo-5-pyrimidinecarb oxylic acid (CAS 98772-05-5, MAR-99), the effect of this compound on the microvascular injury in gastric mucosa induced by 99.5% ethanol in rats was studied. In this experiment, it was found that the elevation of vascular permeability observed at the early state of ethanol-induced gastric mucosal injury was closely correlated with the combined action of histamine and slow reacting substance (leukotriene C4, LTC4). MAR-99 (0.3-10 mg/kg p.o.) prevented dose-dependently the increase in vascular permeability. Furthermore, MAR-99 (10 mg/kg p.o.) improved the decrease in the number of histamine containing cells and histamine content, and prevented the production of LTC4. These results suggest that MAR-99 exerts its anti-microvascular injury effect by regulating the release of histamine and the production of LTC4 in glandular stomach against ethanol, and this effect may contribute to the anti-lesion effect of this compound.

Treatment of sleep apnea and snoring in children

Sleep apnea syndrome in children is usually caused by adenoidal and tonsillar hypertrophy. Here, we report on a typical case of obstructive sleep apnea syndrome, and also discuss recent indications for tonsillectomy in children. A 6-year-old boy came to our hospital suffering from serious obesity and somnolescence. He could not sleep lying down and thus started to sleep in a sitting position. Even during daytime he slept while standing, and exhibited hypersomnolescence. He was 133 cm tall and weighed 80 kg, and tonsillar hypertrophy was recognised. Consequently, tonsillectomy and a weight reducing program were undertaken. The lowest SaO(2) improved from 50% to 70%, and sleep apnea also decreased from 141 to 71 episodes. Moreover, the hypersomnolescence improved.

Post-source decay fragment spectra of cyclomalto-octaose and branched cyclomalto-hexaose by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

gamma-Cyclodextrin, maltosyl-alpha-cyclodextrin and diglucosyl-alpha-cyclodextrin were analyzed using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. All of these compounds have the same molecular weight (M.W. = 1297.15) and consist of only D-glucopyranose. From a comparison of the intensities in the post-source decay (PSD) fragment spectra of these cyclodextrin derivatives, correlation between the chemical structures and the relative intensities in the PSD fragment ions was found. The correlation is considered to be caused by the difference in the number of cleavage sites at the glycosyl binding. It was found that the intensity of the PSD ion resulting from one cleavage is higher than that resulting from two cleavages at a glycosyl bond. The results show that PSD fragment-ion spectrum method used in MALDI-TOF mass spectrometry is a very powerful technique for the structural analyses of the sugar-substituted cyclodextrins.

Studies on antiulcer agents. IV. Antiulcer effects of 2-benzylthio5,6,7,8-tetrahydro-4(3H)-quinazolinones and related compounds

With a view to finding more effective antiulcer agents, a series of 2-benzylthio-5,6,7,8-tetrahydro-4(3H)-quinazolinones and related compounds were synthesized and evaluated in a histamine-stimulated gastric secretion model. The sodium salt of the 2-(dimethylamino)benzylthio derivative (8) showed gastric mucosal protection and gastric antisecretion activities, and was also effective against experimental gastric and duodenal ulcers induced by some ulcerogenic agents. Based on a comparison of the antiulcer properties of 8 with those of the lead compounds (1 and 2) and cimetidine, it appears that, for improvement of antiulcer activity, the reduction of gastric acidity is a more important factor than the reduction of gastric volume output or gastric total acid output.

Effects of 3-[N-(2-chlorobenzyl)amino]-6-(1H-imidazol-1-yl) pyridazine dihydrochloride on various aromatase enzyme systems and experimental breast cancer

The effects of 3-[N-(2-chlorobenzyl)amino]-6-(1H-imidazol-1-yl)pyridazine dihydrochloride (CAS 124070-28-3, MFT-279) on various aromatase enzyme systems and experimental breast cancer were studied. MFT-279 inhibited the aromatase enzyme in vitro with an IC50 value of 2.39 nmol/l. On the other hand, MFT-279 had no effect on cytochrome P-450 dependent reactions of steroid biosynthesis. In pregnant mares' serum gonadotropin (PMSG)-treated female rats, the elevation of ovarian aromatase activity was significantly suppressed by the oral treatment with MFT-279 at 10 and 20 mg/kg. When MFT-279 (20 mg/kg) was orally given to 9,10-dimethyl-1,2-benzanthracene (DMBA)-treated female rats once a day for 28 days, regression of tumors was observed. These results suggest that MFT-279 may be useful for the endocrine therapy of hormone dependent mammary carcinoma.

Studies on antiulcer agents. II. Antiulcer properties of N-(1H-tetrazol-5-yl)-2-anilino-5-pyrimidinecarboxamides inhibiting release of histamine from passively sensitized rat peritoneal mast cells

With the aim of applying mast cell-stabilizing agents as antiulcer agents, N-(1H-tetrazol-5-yl)-2-anilino-5-pyrimidinecarboxamides were synthesized, and initially evaluated pharmacologically for activity in the rat passive cutaneous anaphylaxis test by oral administration. The most active compound 6 was proved to inhibit potently the release of histamine from passively sensitized rat peritoneal mast cells in vitro. When compared with other mast cell-stabilizing agents and an antiulcer agent, compound 6 was found to show excellent gastric mucosal protection and gastric antisecretion activities. Furthermore, compound 6 revealed good activity against acidified aspirin ulcer in rats and water-immersion stress ulcer in rats.

[Health appraisal for work adjustment of freshmen employees--information on health checkup just after entering the corporation and condition in the next fiscal year]

In 1990, 365 (males: 197, females: 168) freshmen employees at the headquarters of a large corporation were examined just after being hired in order to observe their health status. We collected (1) data of physical examinations and questionnaires for symptoms as an ordinary health checkup, (2) information on work adjustment, life patterns, and personal characteristics through interviews conducted by ten public health nurses, and (3) personal records, e.g. birth year. Statistical analyses revealed some notable findings as follows: (1) subjects with higher blood pressure had higher scores of extrovert personality among males, (2) female subjects with greater body mass index had higher scores in such manifestations of personal characteristics such as aggression and discontent with superiors, (3) higher scores of personal characteristics were noted among female subjects working in technical sections, (4) positive correlation between the scores of work adjustment and personal characteristics, (5) higher scores of undesirable life patterns among males and of work maladjustment among elder females, (6) unbalanced meal quality of subjects from rural areas, (7) higher mental tension among younger males from rural areas, and (8) higher scores of dependency and lower morale among younger female subjects. Information on health problems was collected over the 1.5 yrs that followed. More problems were detected among females than among males and among younger females than among elder females. Longitudinal analysis was carried out from just after entry into the company for approximately 1.5 yrs. Health problems in females could be predicted by the data on personal characteristics and work adjustment just after entry. Risk of health problems in male freshmen employees with hobbies and unhealthy drinking habits over the 1.5 yrs that followed was higher than in others. It was concluded that a health interview for freshmen employees by public health nurses is valuable for health care, obtaining information regarding work adjustment, life patterns, and personal characteristics.

Inhibition of nitric oxide synthase attenuates osmotic thirst in the rat

Changes in water intake after intraperitoneal injection of a nitric oxide synthase (NOS) inhibitor was studied in the rat. Administration of NW-nitro-L arginine methyl ester (L-NAME) at a dose of 50 mg/kg attenuated osmotic thirst induced by intraperitoneal injection of hypertonic saline, but did not affect spontaneous intake of water and thirst induced by subcutaneous injection of angiotension II. Pretreatment with L-arginine significantly attenuated the inhibition of osmotic thirst evoked with subsequent L-NAME. Administration of NW-nitro-D-arginine methyl ester (D-NAME) altered neither the spontaneous nor the osmotic drinking behavior. These findings suggest that NO may affect the osmotically induced drinking.

Studies on antiulcer agents. I. Synthesis and pharmacological properties of ethyl 2-[(1H-benzimidazol-2-yl)sulfinylmethyl]-4-dimethylamino-5- pyrimidinecarboxylate, a new H+/K(+)-ATPase inhibitor possessing mucosal protective activity

Ethyl 2-[1H-benzimidazol-2-yl)sulfinylmethyl]-4-dimethylamino-5- pyrimidinecarboxylate (2) has been synthesized and evaluated for antiulcer properties. Compound 2 is a H+/K(+)-ATPase inhibitor that affords mucosal protection against absolute ethanol-induced gastric lesions in rats after oral and parenteral administrations. On the other hand, omeprazole, a representative H+/K(+)-ATPase inhibitor, showed mucosal protective action only after oral administration, indicating that it required gastric acid secretion to generate activity. The antiulcer activity of 2 in animal models, such as water-immersion stress-induced gastric ulcer in rats and acidified aspirin-induced gastric ulcer in rats, was three times higher than that of cimetidine.

Variations in the level of urinary thiobarbituric acid reactant in healthy humans under different physiological conditions

The level of urinary thiobarbituric acid (TBA) reactants in healthy human subjects due to malonaldehyde derivatives was measured to assess the lipid peroxidation status of the whole body. For each subject the TBA reactant level over a day varied over a 2-3 fold range while the daily level varied over a 1.5-3 fold range under normal life-style conditions. One of the factors causing an increase in the reactant level within a single day may be the subjects's physical activity, because the reactant level of each subject was higher in the afternoon or in the evening than in the morning. Remaining awake all night or hard exercise caused a dramatic increase in the reactant level over a day and in the daily reactant level. The reactant level within a single day for a subject was increased 5.5 fold and the daily level 3 fold by remaining awake all night, and the level within a day was increased 22 fold by hard exercise while the corresponding daily level was increased 7 fold. It is unlikely that food, alcohol and smoking greatly affect the reactant level. The results suggest that increased physical activity enhances lipid peroxidation in the whole body and thus the increased urinary excretion of malonaldehyde derivatives.

Pathology of olfactory mucosa in patients with Alzheimer's disease

Characteristic changes that appear in the biopsied olfactory mucosa of patients with Alzheimer's disease (AD) were examined with immunohistochemical staining. Specimens were obtained from patients with clinical diagnoses of AD. Patients with vascular dementia and age-matched patients without dementia were used for controls. In most AD cases, neurofibrillary tangle-like abnormal tau protein (Tau) immunoreactivity was seen in the dendrites and perikarya of the olfactory receptor cells and in the nerve bundles. A senile plaque-like extracellular mass was found in the olfactory epithelium, and it reacted strongly to an anti-Tau antiserum and weakly to an anti-amyloid-beta protein antiserum. Ubiquitin (Ubq) immunoreactivity was also observed in the dendrites. Tau immunoreactivity of the perikarya and extracellular mass, and Ubq immunoreactivity were especially characteristic of the olfactory mucosa of AD patients. From these results, it is clear that the same pathologic changes in the brain are also present in the olfactory mucosa of patients with AD. Not only disruption of the central olfactory pathway, but also an olfactory disturbance of AD patients is caused by peripheral changes. Furthermore, an olfactory mucosal biopsy could be a useful method for a definitive diagnosis of AD.

Effect of 1,6-dihydro-2-[2-(2-methylpropoxy)anilino]-6-oxo-5-pyrimidinecarboxylic acid on gastric mucosal defensive factors and gastric secretion in rats

1,6-dihydro-2-[2-(2-methylpropoxy)anilino]-6-oxo-5-pyrimidinecarbo xylic acid, (MAR-99, CAS 98772-05-5) (10-30 mg/kg i.g.) improved the reduction of gastric blood flow rate induced by the administration of 99.5% ethanol or acidified-acetylsalicylic acid (ASA). In addition, MAR-99 (3 x 10(-6)-3 x 10(-5) mol/l) protected dose-dependently the damage of epithelial cells induced by ulcerogenic agents such as ethanol or acidified-ASA. MAR-99 (1-10 mg/kg p.o.) prevented dose-dependently the reduction of hexosamine content in glandular stomach. Furthermore, MAR-99 (10-30 mg/kg i.g.) improved the decrease in gastric potential difference induced by 99.5% ethanol and acidified-ASA. MAR-99 (10-30 mg/kg p.o.) significantly inhibited the lesion formation induced by 99.5% ethanol and such effect of this compound was not attenuated by the pretreatment with indomethacin. Furthermore MAR-99 (10 and 30 mg/kg p.o.) had no effect on the prostaglandins (PGE2 and I2) contents in the stomach of normal rats. In pylorus-ligated rats, MAR-99 (3-100 mg/kg i.d.) showed a weak or no effect on acidity and pepsin activity in gastric juice, although this compound decreased dose-dependently the volume of gastric juice. In perfused stomachs, MAR-99 (30-100 mg/kg i.d.) slightly prevented the acid secretion induced by carbachol and pentagastrin. However, MAR-99 did not affect the acid secretion stimulated by histamine. These results indicated that anti-ulcer effect of MAR-99 was mainly due to maintenance of the gastric mucosal resistance.

Disseminated Mycobacterium avium-intracellulare infection in a patient with myelodysplastic syndrome (refractory anemia)

A 31-year-old woman presented with fever and arthralgia. Despite treatment with antimicrobials and corticosteroids, her symptoms persisted. A diagnosis of myelodysplastic syndrome (MDS)-refractory anemia (RA) was made by pancytopenia, dysplasia, and trisomy 8. Cultures of bone marrow, blood, and gastric juice showed Mycobacterium avium-intracellulare (MAI). She was treated with antimycobacterial drugs and recombinant human G-CSF/M-CSF and showed an initial response, but spike fever recurred and pancytopenia progressed. Hepatosplenomegaly and marked retroperitoneal lymphadenopathy were revealed, indicating further dissemination of MAI. Treatment with recombinant human GM-CSF and very-low-dose cytosine arabinoside, was started but was not effective. This case showed significant reduction in peripheral blood T-lymphocytes, especially the CD4+ population, and low immunoglobulin levels. Immunodeficiency state associated with long-term steroid therapy and MDS seemed to contribute to the development of the disseminated infection with MAI.

Anti-ulcer effect of 1,6-dihydro-2-[2-(2-methylpropoxy) anilino]-6-oxo-5-pyrimidinecarboxylic acid on experimental gastric ulcers in rats

The effects of 1,6-dihydro-2-[2-(2-methylpropoxy) anilino]-6-oxo-5-pyrimidinecarboxylic acid (MAR-99, CAS 98772-05-5) on various experimental gastric ulcers were studied in rats. MAR-99 (3-100 mg/kg, p.o. or i.d.) showed the anti-ulcer effect in Shay-, stress, acetylsalicylic acid (ASA)- and compound 48/80-ulcer models and significantly accelerated healing of acetic acid-induced gastric ulcer in rats. In addition, MAR-99 (1-10 mg/kg p.o.) decreased dose-dependently the gastric mucosal damage induced by necrotizing agents such as 99.5% ethanol, 0.6N HCl and 0.2 N NaOH. These results indicate that MAR-99 may be useful for the treatment of gastric ulcer in human.

Olfactory mucosa of patients with olfactory disturbance following head trauma

The olfactory mucosa in 7 patients with olfactory disturbance following head trauma were sampled for biopsy with special biopsy forceps and examined by immunohistochemical staining with anti-neuron-specific enolase (NSE) and S-100 protein (S-100) antibodies. The residual olfactory receptor cells and nerve bundles were counted, and the degree of degeneration was determined. In 5 patients, olfactory receptor cells that reacted with anti-NSE antiserum remained, although the number varied with the patient, and in 2 patients the receptor cells disappeared. In the lamina propria, the S-100-immunoreactive olfactory nerves were retained in 6 patients. The outcome was poor in all cases regardless of the number of residual receptor cells and nerve bundles. These results indicate that the degree of impairment of the peripheral olfactory region after head trauma differs from case to case, and that even if the receptor cells and nerve bundles remain, it is difficult to improve the condition, although some cases of malingering may be contained.

Sleep spindle frequency changes during the menstrual cycle

Five healthy adult women aged 20 to 28 had 12-15 polysomnographic recordings, as well as daily basal body temperature and multiple LH, FSH, estrogen and progesterone measurements taken during a single menstrual cycle. Sleep stages were scored both visually and with a spindle and delta-wave, real-time, automatic analysing system. A cubic growth-curve model showed that the frequency of sleep spindles changed markedly over the menstrual cycle: spindle frequency was lowest about 18 days before onset of menses and highest 3 days before onset of menses. Slow waves did not change. The percentages of Stage 1 and REM sleep showed small changes during the menstrual cycle, and other parameters of visually scored sleep showed no tendency to change. Spindle frequency may reflect the effects of sex hormones on the reticular thalamic nucleus and may be a quantitative marker of premenstrual sleep disturbances.

[Abnormal tau protein expression in biopsied human olfactory mucosa]

Abnormal tau protein expression was immunohistochemically examined in biopsied human olfactory mucosa. The olfactory mucosa of 25 patients with olfactory disturbances, whose structures were relatively preserved, was immunostained with a polyclonal antibody derived from neurofibrillary tangles from the brains of patients with Alzheimer's disease. Abnormal tau protein immunoreactivity was found in the olfactory vesicles, dendrites and perikarya of the olfactory receptor cells in the epithelium and olfactory nerve bundles in the lamina propria. This immunoreactivity in the olfactory nerve bundles was observed in patients in their teens to 80's, and the immunoreactivity of the olfactory vesicles and dendrites of the olfactory receptor cells was widely distributed in patients in their 30's to 70's. On the other hand, the immunoreactivity of the perikarya of the olfactory receptor cells was observed only in patients in their 50's and 60's. These results indicate that abnormal tau protein accumulation of perikarya is a pathological change and is related to aging of the olfactory neurons.

[Definitive diagnosis of Alzheimer's disease using olfactory mucosal biopsy]

Characteristic changes appearing in the biopsied olfactory mucosa of Alzheimer's disease (AD) patients were investigated using immunohistochemical staining. Specimens were obtained from 6 patients who were clinically diagnosed with AD, 2 patients with cerebrovascular dementia and 5 age-matched patients with olfactory disturbance without dementia. In most AD cases, polyclonal tau protein immunoreactivity was seen in the dendrites, perikarya of the olfactory receptor cells in the olfactory epithelium and the olfactory nerve bundles in the lamina propria. In a few cases, tau protein immunoreactivity was found in the extracellular mass in the epithelium. Ubiquitin immunoreactivity was seen is the dendrites of olfactory receptor cells. On the other hand, in control cases, only dendrites and olfactory nerve bundles reacted to anti-polyclonal tau protein antiserum in a few cases. These results indicate that the neurofibrillary tangle-like tau protein immunoreactivity in the perikarya senile plaque-like extracellular mass and ubiquitin immunoreactivity in the olfactory epithelium were characteristic changes in AD, and olfactory mucosal biopsy is a useful method for the definitive diagnosis of AD.

Effect of pravastatin on human sleep

To evaluate the effect of pravastatin, an HMG-CoA reductase inhibitor, on sleep, the drug or a placebo was administered to 5 healthy adults for 16 days by the double-blind method. Pravastatin caused no changes in sleep parameters. This indicates that it had no effect on human sleep for the following possible reasons: Being hydrophilic, the drug does not readily cross the blood-brain barrier. It does not inhibit prostaglandin D2 synthase, a possible sleep-inducing substance. It was thought that a decrease in the total cholesterol level in the blood has no effect on sleep in healthy adults.

Enhancement and neutralization of feline infectious peritonitis virus infection in feline macrophages by neutralizing monoclonal antibodies recognizing different epitopes

The interaction between the enhancing and neutralizing activities of three monoclonal antibodies (MAbs) (5-6-2, 6-4-2 and 7-4-1) to the spike protein of feline infectious peritonitis virus (FIPV) strain 79-1146 was determined using feline macrophages. At a high MAb concentration, all of the three MAbs completely inhibited the FIPV infection at 37 C. However, two of them (6-4-2 and 7-4-1) enhanced FIPV infection when either the MAb concentration or reaction temperature was lowered. These MAbs also exerted an immediate infectivity-enhancing activity for up to 10 min of reaction and by 20 min, neutralizing activities were observed. Only MAb 5-6-2 consistently showed neutralizing activity regardless of the reaction conditions. Competition with sera from cats experimentally infected with FIPV strain 79-1146 or feline enteric coronavirus strain 79-1683 showed that the two epitopes recognized by MAb 5-6-2 and MAb 6-4-2, respectively, are also recognized by the natural host.