Cytochrome oxidase immunohistochemistry in rat brain and dorsal root ganglia: visualization of enzyme in neuronal perikarya and in parvalbumin-positive neurons

Histochemical detection of cytochrome oxidase activity has been widely used to deduce patterns of neuronal electrical activity in the CNS. Here we investigated the utility of cytochrome oxidase localization by immunohistochemistry and compared immunostaining with histochemical staining patterns in dorsal root ganglia of the rat. In addition, a limited survey of cytochrome oxidase immunostaining density within what are thought to be highly active parvalbumin-immunoreactive neurons was conducted. The immunohistochemical approach produced granular cytoplasmic immunolabelling in neuronal cell bodies and allowed identification of individual labelled cells in all brain regions including those within dense immunoreactive networks of neuropil. Neuronal somata exhibited a wide range of staining densities which were particularly evident in the hippocampus and dorsal root ganglia. The distribution of neurons intensely immunoreactive for cytochrome oxidase within various structures was consistent with previous histochemical descriptions of enzyme activity. Densitometric measurements of immunohistochemical reaction product in individual neurons of hippocampus, substantia nigra, cerebellum and dorsal root ganglia showed that the rate of product deposition was linear with time under conditions chosen for comparisons of staining density. Quantitative analysis of cytochrome oxidase immunohistochemical and histochemical staining densities within the same cells in adjacent sections of dorsal root ganglion gave a correlation coefficient of r = 0.75 (P less than 0.001). In sections processed immunohistochemically for both cytochrome oxidase and parvalbumin, most but not all parvalbumin-containing cells displayed dense cytochrome oxidase immunolabelling. Conversely, many examples were found of neurons that were densely stained for cytochrome oxidase, but lacked parvalbumin. Immunohistochemistry for cytochrome oxidase reveals the enzyme in neuronal cell bodies with a clarity not usually seen with the histochemical method. Combination of this immunohistochemical approach with simultaneous immunolabelling of other neuronal markers, as shown here in the case of parvalbumin, is expected to assist the elucidation of patterns of activity in neurochemically identified cell types and anatomically defined neural systems.

Detection of tumour antigens in sera of patients with hepatocellular carcinoma using monoclonal antibodies

A total of 70 serum samples taken from patients with hepatocellular carcinoma (HCC), acute viral hepatitis and cirrhosis and normal individuals were tested in a binding inhibition immunofluorescence assay using 5 mouse monoclonal antibodies (2G9, 3H11, 3H12, 1C7, 3H5) specific for hepatoma cells. Seven out of the 30 HCC sera (23.3%) inhibited the binding of one of these antibodies, 3H11. This detection of antigen 3H11 or antigens of similar structure in HCC sera was significantly more frequent than in control sera (1/40 = 2.5%) (Fisher's exact test, p = 0.009; df = 1, relative risk calculated by the odds ratio in a 2 x 2 table = 12.0). The presence of this antigen was unrelated to the hepatitis B surface antigen and alphafetoprotein status. Thus it would be of value particularly for the detection of hepatitis B negative or alphafetoprotein negative liver cancers.

Linkage of a nasopharyngeal carcinoma susceptibility locus to the HLA region

The frequency of nasopharyngeal carcinoma is nearly 100-fold higher in southern Chinese than in most European populations. Earlier studies have suggested that an increased risk of nasopharyngeal carcinoma is associated with specific haplotypes in the HLA region: relative risks slightly over twofold were found for haplotypes A2, Bw46 and the antigen B17. We now report a linkage study based on affected sib pairs which suggests that a gene closely linked to the HLA locus confers a greatly increased risk of nasopharyngeal carcinoma. The maximum likelihood estimate is of a relative risk of approximately 21. The relationship between this suspected disease susceptibility gene (or genes) and known viral and environmental aetiological factors remains to be elucidated.

Tonic enhancement of the sensitivity of baroreceptor reflex response by endogenous substance P in the rat

Modulation of baroreceptor reflex (BRR) by endogenous substance P (SP) in the brain was investigated in rats anesthetized with pentobarbital sodium. Intracerebroventricular administration of the undecapeptide (15 or 30 nmol) and its antagonist, (D-Pro2, D-Trp7,9)-SP (30 or 60 nmol) or SP antiserum (1:20), respectively, promoted a significant increase and decrease in the sensitivity of BRR response. Prolonging the endogenous activity of SP with the aminopeptidase blocker, bestatin (200 nmol) or with the endopeptidase-24.11 inhibitor, phosphoramidon (200 nmol) significantly augmented the same reflex. Combining the undecapeptide with either peptidase blocker, moreover, promoted additional potentiation of the BRR response. On the other hand, simultaneous administration of bestatin and (D-Pro2, D-Trp7,9)-SP produced a reduction of the augmented effect of bestatin on the sensitivity of BRR response. Bilateral microinjection of SP (600 pmol) or an antiserum against SP (1:20) into the nucleus tractus solitarius (NTS) elicited respectively an enhancement of and reduction in the BRR response. These data suggest that neurons that contain SP may participate in central cardiovascular control by tonically enhancing the sensitivity of the BRR response, possibly via an action on the NTS.

Cytochrome oxidase from thermophilic bacterium PS3 contains a fourth protein subunit

Monoclonal antibodies prepared against subunits II and IV of beef heart cytochrome oxidase were found to cross-react with thermophilic bacterial PS3 oxidase. Each individual antibody affects the enzymatic activity. "Western" blot analyses showed that subunit II antibodies of beef heart recognized subunit II of PS3 and subunit IV antibody likewise recognized a fourth protein subunit on slab gels. This fourth subunit previously thought to be a contaminant or a degradation product has a molecular weight of about 10,500 on SDS-gels, and appears to exist in stoichiometric amount. We have extracted this subunit from slab gels and compared its amino acid composition with that of subunit III.

Immunogenicity and safety of low doses of recombinant yeast-derived hepatitis B vaccine

The immunogenicity and safety of recombinant yeast-derived hepatitis B vaccine given in doses of 0.6 microgram, 1.25 microgram, 2.5 micrograms and 5.0 micrograms were studied in 4 comparable groups of children aged 1-12 years. All children received three doses of vaccine at time 0, 1 month and 5 months. Immunogenicity appeared to be satisfactory in all 4 groups of children. In the early phase of the study, a dose-response relationship was observed but there was no significant difference in the geometric mean titre among all 4 groups for any period studied. Antibody levels peaked at 9 months, declining thereafter. The geometric mean titre one year after the first vaccine dose was not significantly lower than that at the peak (9 months) in any individual group studied. The second year geometric mean titre was similar in all 4 groups and lower than that of the first year. Sero-conversion with antibody titres greater than or equal to 10 mIU/ml was 100% in the 5.0 micrograms group and greater than 90% in the other 3 groups. There were no adverse reactions of any significance. The immunogenicity of recombinant yeast-derived hepatitis B vaccine was found to be adequate even at as low a dosage as 0.6 microgram when administered in a 3-dose regimen.

Interaction between angiotensin III and alpha 2-adrenoceptors of the medulla oblongata involved in cardiovascular regulation in the rat

We evaluated, in adult, male Sprague-Dawley rats anesthetized with pentobarbital sodium, possible interaction between angiotensin III (AIII) and the alpha 2-adrenoceptors in the medulla oblongata that are involved in cardiovascular regulation. The hypotensive and negative chronotropic and inotropic actions of the alpha 2-adrenoceptor agonist, guanabenz, were used as our experimental index. Intracerebroventricular (i.c.v.) administration of AIII (100 or 200 pmol) significantly attenuated the cardiovascular suppressive effects of the aminoguanidine compound (25 or 50 micrograms/kg, i.v.). Bilateral microinjection of AIII (20 or 40 pmol) to the nucleus reticularis gigantocellularis (NRGC), a medullary site believed to be intimately related to the antihypertensive action of guanabenz, produced similar results. In addition, i.c.v. administered AIII (200 pmol) altered the effects of guanabenz on the arterial pressure-related neurons in the NRGC, in a manner that paralleled the blunted vasodepressive action of the aminoguanidine compound by the heptapeptide. When applied microiontophoretically, AIII also significantly decreased the responsiveness of arterial pressure-related neurons in the NRGC to guanabenz. These findings suggest that AIII may interact with the alpha 2-adrenoceptors located in the NRGC that are involved in central cardiovascular regulation.

Detection of integrated hepatitis B virus DNA in hepatocellular carcinoma cell lines by nonradioactive in situ hybridization

A sensitive and specific nonradioactive in situ hybridization method capable of detecting single-copy integrated hepatitis B virus (HBV) DNA sequences in hepatocellular carcinoma (HCC) cell lines was developed. In situ hybridization of biotinylated HBV (adr, adw) DNA probes with nine different human HCC cell lines were carried out in 96-well microtiter plates. Integration was detected in HCC cell lines HCCM, Hep3B, huH-1, huH-4, and PLC/PRF/5. Detection of single-copy HBV DNA sequences was also achieved in Hep3B and huH-4. HCC cell lines HepG2, HUH-6, HUH-7, Mahlavu, and the non-HCC control MCF-7, gave clear negative results. These results show a 100% correlation with those obtained by Southern blot hybridization assay. The results demonstrate that nonradioactive detection of single-copy integrated HBV DNA sequences in HCC cell lines is possible by the method described, which has potential application for viral genome analysis requiring in situ hybridization.

Tonic suppression of baroreceptor reflex by endogenous neurotensin in the rat

We evaluated the modulatory role of endogenous neurotensin (NT) in baroreceptor reflex (BRR) response in Sprague-Dawley rats anesthetized with pentobarbital sodium. Intracerebroventricular (i.c.v.) administration of NT (15 or 30 nmol) significantly reduced the sensitivity of the BRR response. Blocking the endogenous activity of the tridecapeptide with its specific antagonist, (D-Trp11)-NT (4 or 8 nmol) or antiserum against NT (1:20); or inhibiting the aminopeptidases with bestatin (200 nmol), on the other hand, promoted a potentiation of BRR response. When administered together with bestatin (200 nmol), the suppressive effect of NT (15 nmol) on the BRR response was further enhanced, as was the augmentative action of (D-Trp11)-NT (4 nmol). Upon microinjection into the bilateral nucleus tractus solitarius (NTS), NT (600 pmol) and (D-Trp11)-NT (150 pmol) respectively elicited a reduction and enhancement of the BRR response. These results suggest that neurons that contain NT may participate in central cardiovascular regulation by tonically suppressing the BRR, possibly via an action on the NTS where baroreceptor afferents terminate.

Aetiology of nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC), a rare tumour in most parts of the world, occurs in high frequencies in China and South East Asia and is particularly high among the Southern Chinese. In certain parts of China the incidence may reach 50 per 10(5) per year while in most other ethnic groups the incidence is very low, e.g. among Caucasians the incidence is less than 1 per 10(5) per year. These marked geographic and racial differences in incidence have stimulated much research into the aetiology of this cancer. Potential aetiological factors will have to explain this 50-100 fold difference in incidence. Both genetic and various environmental factors have been postulated. This paper discusses the role of the Histocompatibility Locus Antigen (HLA), Epstein Barr Virus and chemical carcinogen including salted fish in the development of NPC.

Involvement of coerulospinal noradrenergic pathway in fentanyl-induced muscular rigidity in rats

Unilateral, site-specific microinjection of fentanyl (2.5 micrograms/50 nl) into the locus coeruleus (LC) in Sprague-Dawley rats anesthetized with ketamine evoked a significant increase in the electromyographic activity recorded from both caudal lateral extensor and gastrocnemius muscles. This correlate of opiate-induced muscular rigidity was appreciably antagonized by a pretreatment with the specific alpha 1-adrenoceptor blocker, prazosin (250 micrograms/kg, i.v.). On the other hand, an equimolar dose (0.65 mumol/kg) of the specific alpha 2-adrenoceptor blocker, yohimbine (0.23 mg/kg, i.v.) failed to prevent the occurrence of fentanyl-induced EMG activation. We suggest that the coerulospinal noradrenergic pathway may be directly involved in the elicitation of muscular rigidity by fentanyl, possibly via alpha 1-adrenoceptors in the spinal cord.

Differential effects of prazosin and yohimbine on fentanyl-induced muscular rigidity in rats

Whereas muscular rigidity is a well-known phenomenon that is related to anesthesia induced by large doses of narcotic drugs, the precise underlying mechanism(s) remain to be fully elucidated. This study investigated the possible role of noradrenergic neurotransmission and the participation of alpha-adrenoceptors in this phenomenon. Male Sprague-Dawley rats, under ketamine-induced anesthesia (120 mg/kg, i.p.) and with proper control of respiration, body temperature and end-tidal CO2 were used. Intravenous administration of fentanyl (100 micrograms/kg) consistently caused a significant increase in the electromyographic (EMG) activity, recorded from both gastrocnemius and abdominal rectus muscles. This implied muscular rigidity was markedly antagonized by pretreatment with the specific alpha 1-adrenoceptor blocker, prazosin (50 or 250 micrograms/kg, i.v.). This antagonism occurred in spite of a high level of fentanyl in the plasma, as determined by radioimmunoassay. The specific alpha 2-adrenoceptor blocker, yohimbine (1.15 or 2.3 mg/kg, i.v.), on the other hand, not only failed to prevent fentanyl-induced activation of the EMG, but actually potentiated the response. It is concluded that noradrenergic neurotransmission, possibly originating from the locus coeruleus, may participate in the elicitation of muscular rigidity by fentanyl. Furthermore, this process may involve an excitatory action through alpha 1-, and an inhibitory action through alpha 2-adrenoceptors, in the spinal cord.

Involvement of postsynaptic alpha 2-adrenoceptors and guanine nucleotide-binding protein in guanabenz-induced cardiovascular suppressant effects in the rat

In adult, male Sprague-Dawley rats anesthetized with pentobarbital sodium, pretreatment with the catecholamine-depleting agent, reserpine (150 micrograms, i.c.v.) significantly antagonized the hypotensive and negative inotropic and chronotropic effects of guanabenz, either given intravenously (100 micrograms/kg) or microinjected bilaterally (5 micrograms) into the nucleus reticularis gigantocellularis (NRGC), a medullary site of action for this centrally acting antihypertensive agent. Pretreating animals with microinjection of the selective norepinephrine neurotoxin, DSP4 (50 micrograms), into the bilateral NRGC, on the other hand, did not appreciably blunt the cardiovascular suppressive actions of the aminoguanidine compound. I.c.v. administration of pertussis toxin (2.5 micrograms), which potentially blocks the action of two guanine nucleotide-binding proteins (Gi and Go), significantly antagonized the circulatory inhibitory effects of guanabenz (100 micrograms/kg, i.v.). More specifically, this blocking effect was still apparent upon microinjecting pertussis toxin (250 ng) into the bilateral NRGC. These data suggest that both pre- and postsynaptic alpha 2-adrenoceptors, and a pertussis toxin sensitive G-protein(s) (Gi and/or Go), in the NRGC are crucial to the expression of the cardiovascular suppressant actions of guanabenz.

Relative predispositional effects (RPEs) of marker alleles with disease: HLA-DR alleles and Graves disease

A method is described to reveal the relative predispositional effects (RPEs) (predisposing, protective, or neutral) of the HLA alleles or of any other marker system that is associated with a disease. When the disease is associated with two or more alleles of a locus, the RPE method identifies the associations sequentially according to their strength; thus the problem that a strong association with one allele can create misleading deviations in the frequencies of other alleles is alleviated. Using this method, we have examined the relative effects of HLA-DR alleles in susceptibility to Graves disease in the Caucasian population. The well-established positive association with DR3 was confirmed as the strongest effect. In addition, a negative association was found between DR5 and Graves disease. The reduced frequency of DR5 among patients is statistically significant and is not a result of the increase in DR3. Finally, when patients were divided according to the presence or absence of eye disease, the latter showed a significant increase in the frequency of DR4. With family data, linkage to HLA of Graves disease was established in both Caucasian and Chinese families by the sib-pair method.

HLA Bw46 and DR9 associations in Graves' disease of Chinese patients are age- and sex-related

The HLA-A, -B antigens in 159 Chinese patients with Graves' disease were compared with those of 330 controls. The HLA-DR antigens of the patients were also studied in 100 normals. Analysis of the increased prevalence of Bw46, according to the sex and age of onset of disease of the patients, showed that the strong association of Bw46 resided with male patients (n = 58), Pc = 0.0000052, RR = 4.2. Although the frequency of Bw46 was also increased in female patients (n = 101), it was statistically not significant. For the DR9 antigens, the strong association with male patients was also observed, viz. Pc = 0.019, RR = 3.2. Males also had higher risks of Graves' disease if they had homozygous Bw46 at presentation. Further analysis by age of onset of disease revealed the segregation of significant association with Bw46 for the males at 1-19 yr, Pc = 0.0011, RR = 17.5 HLA associations (Bw46 and DR9) with Graves' disease in Chinese are observed primarily in males, especially those whose known ages of onset of the disease are between 1-19 yr (Bw46).

Biotyping of Campylobacter pylori

Ninety-one biochemical tests were done on each of 50 strains of Campylobacter pylori isolated from the gastric mucosa of patients with gastritis and peptic ulcers in Singapore. The API ZYM system distinguished three biotypes of C. pylori. The organism was found to be biochemically different from C. jejuni and C. coli. We propose a biochemical identification kit that would be of use in identifying and differentiating biotypes of C. pylori, and would distinguish them from C. jejuni and C. coli.

Fentanyl-induced muscle rigidity in unanesthetized and ketamine- or thiopental-anesthetized rats

This study was undertaken to search for an alternative experimental model in the evaluation of fentanyl-induced muscle rigidity. Unanesthetized, spontaneously ventilating Sprague-Dawley rats, and rats anesthetized with either ketamine or thiopental whose ventilation was mechanically controlled, were studied. Intravenous administration of fentanyl (25, 50, or 100 micrograms/kg) caused an increase in electromyographic (EMG) activity in both unanesthetized and ketamine-anesthetized, but not in thiopental-anesthetized, animals. Muscle rigidity was more prominently manifested in the gastrocnemius muscle, when compared with the rectus abdominis muscle. Hypoxemia was exhibited during the course of rigidity by both spontaneously ventilating and ketamine-anesthetized rats, but not by thiopental-anesthetized animals. In addition, unanesthetized, spontaneously ventilating rats developed hypercarbia and respiratory acidosis. The authors suggest that, in addition to using unanesthetized animals, EMG activity in the gastrocnemius muscle of rats anesthetized with ketamine in whom ventilation is controlled may provide an alternative approach in the evaluation of fentanyl-induced muscle rigidity.

Passive electrical properties of spontaneously active neurons in the nucleus reticularis gigantocellularis of the cat

We evaluated in chloralose-urethane anesthetized cats the passive electrical properties of 25 spontaneously active neurons in the nucleus reticularis gigantocellularis (NRGC) of the medulla oblongata. Compared to other mammalian brain regions, these reticular cells in general possessed higher input resistance, shorter membrane time constant and first equalizing time constant, and longer somatodendritic electrotonic length factor. It is discussed that, by providing a synaptic machinery for quick and sensitive response to afferent inputs and an efficacious interplay between temporal and spatial summation, these electrical membrane properties may account for the spontaneous and irregular discharge pattern characteristic of the NRGC neurons.

Involvement of locus coeruleus and noradrenergic neurotransmission in fentanyl-induced muscular rigidity in the rat

Whereas muscular rigidity is a well-known side effect that is associated with high-dose fentanyl anesthesia, a paucity of information exists with regard to its underlying mechanism(s). We investigated in this study the possible engagement of locus coeruleus of the pons in this phenomenon, using male Sprague-Dawley rats anesthetized with ketamine. Under proper control of respiration, body temperature and end-tidal CO2, intravenous administration of fentanyl (50 or 100 micrograms/kg) consistently promoted an increase in electromyographic activity recorded from the gastrocnemius and abdominal rectus muscles. Such an induced muscular rigidity by the narcotic agent was significantly antagonized or even reduced by prior electrolytic lesions of the locus coeruleus or pretreatment with the alpha-adrenoceptor blocker, prazosin. Microinjection of fentanyl (2.5 micrograms/50 nl) directly into this pontine nucleus, on the other hand, elicited discernible electromyographic excitation. It is speculated that the induction of muscular rigidity by fentanyl may involve the coerulospinal noradrenergic fibers to the spinal motoneurons.

Screening for NPC

This paper discusses the criteria of cancer screening in general and of nasopharyngeal carcinoma in particular. It also discusses the screening results in China and the strategy for screening of this cancer in Singapore.

The hepatitis B immunization programme in Singapore

A voluntary immunization programme to prevent perinatal transmission of hepatitis B virus (HBV) infection in Singapore was implemented on 1 October 1985 as an integral component of the national childhood immunization programme. Up to April 1988, a total of 68,845 mothers who attended government maternal and child health clinics were screened for the disease. Of these, 2432 (3.5%) were positive for hepatitis B surface antigen (HBsAg) and 904 (1.3%) for hepatitis B e antigen (HBeAg). Virtually all the babies born to carrier mothers completed the full immunization schedule; and in addition, those of HBeAg-positive mothers were given a dose of hepatitis B immunoglobulin at birth. The hepatitis B immunization programme was extended on 1 September 1987 to cover all newborns. About 90% of the 15,943 babies delivered in government institutions from September 1987 to April 1988 were immunized at birth, with the subsequent doses being administered at maternal and child health clinics at 4-6 weeks and 5 months later. More than 85% of the children given the full course of plasma-derived and yeast-derived hepatitis B vaccine from birth continued to have protective antibody to HBV two years after immunization. The programme is being closely monitored to assess the duration of immunity and the need for booster doses, while seronegative adults are also being encouraged to be vaccinated.

HLA and allopurinol drug eruption

Strong HLA associations were found in Southern Chinese patients with skin eruptions due to allopurinol. The positive associations were with AW33 (Pc = 1.7 x 10(-5); relative risk [RR] = 15.0, 95% confidence limit 5.2-42.9) with B17/BW58 (Pc = 2.9 x 10(-9); RR = 46.3, 95% confidence limit 10.3-209.2). The negative association was with A2 (Pc = 8.3 x 10(-5), RR = 0). The findings suggested a genetic predisposition to cutaneous drug reactions.

Effects of subunit V antibodies on the topology of the subunit and the activity of beef heart cytochrome-c oxidase

Redox-sensitive epitopes on subunit V of beef heart cytochrome-c oxidase were demonstrated previously using polyclonal subunit-specific antibodies raised in rabbits. The antibodies only slightly inhibited electron transfer, and the accessibility of their epitopes depended on the presence of a membrane and on the redox state of the oxidase. The present paper describes additional preparations of antibodies raised against subunit V. These antibodies have an even higher subunit specificity, they are more than three times as inhibitory against electron transfer, and their binding does not require a membrane. Moreover, the redox-sensitive nature of their binding to detergent-dispersed oxidase is sensitive to the method of its isolation. We discuss inferences that can be drawn from a detailed quantitative comparison of the interactions of the two antibody preparations with the antigen in different environments. The techniques used in the comparison can be used to examine other perturbants of the oxidase as to their effects on specific segments of the enzyme.