Eosinophilopoietic factors prime eosinophils for increased interleukin-8 generation

Recent studies have identified eosinophils as a cellular of various cytokines, indicating that eosinophils play not only an effector role but also a regulatory role within the allergic inflammatory cell network. Because eosinophilopoietic factors are known to stimulate various functions of eosinophils, we examined the effect of interleukin (IL)-5 on chemoattractant-induced IL-8 generation from eosinophils. Although IL-5 alone induced little or no IL-8 production from eosinophils, short-term preincubation with IL-5 markedly enhanced the eosinophil IL-8 generation caused by C5a plus cytochalasin B (CB). IL-3 also potentiated C5a-induced IL-8 generation. Both factors were active at picomolar concentrations. Furthermore, competitive polymerase chain reaction (PCR) experiments revealed that the enhancement occurred at the pretranslational level. Since eosinophils in allergic inflammation are believed to be activated by these eosinophilopoietic factors, eosinophil-derived cytokines may play more important roles in the allergic inflammatory cell network than has been previously supposed.

[A case of pleural metastasis of invasive thymoma with pulmonary metastasis responding to chemotherapy with cyclophosphamide and prednisolone]

The patient, a 48-year old male, was seen with hoarseness in December 1990. A chest radiograph and chest CT scan showed an anterior mediastinal mass. Median sternotomy revealed epithelial thymoma with involved partial lung and pericardium. After surgery, he received external radiation to the mediastinum. One year later he was given another 40 Gy external radiation in the cervical and mediastinal recurrence region. In May 1994, a chest CT scan revealed an extrapleural and bilateral lung mass. Histological examination revealed recurrent epithelial thymoma in the left cervical muscle biopsy, so treatment with cyclophosphamide and prednisolone were begun. A dose of 100 mg/body/day of cyclophosphamide and a dose of 10 mg/body/day of prednisolone were administered every 2 week. Complete remission was induced with four cycles of this treatment of cyclophosphamide and prednisolone. The chemotherapy was thus continued for 20 cycles in 14 months. This chemotherapy with cyclophosphamide and prednisolone appeared to be useful and safe for recurrent thymoma at the outpatient clinic level.

Eotaxin is a potent chemotaxin for human basophils

We studied the effect of eotaxin, a novel eosinophil-active CC chemokine with high target cell specificity, on human basophils. Eotaxin induced higher levels of chemotactic response with a lower ED50 compared with RANTES in basophils; half-maximal migration occurred at a concentration of approximately 3 nM. On the other hand, it exerted only a marginal effect on either histamine release or leukotriene C4 generation. In addition, nested PCR amplification experiments revealed the expression of CC CKR3, a putative receptor for eotaxin, on basophils. Since accumulation of both basophils and eosinophils is an important aspect of allergic inflammation, eotaxin potentially plays a pathogenic role in allergic disorders by inducing migration of both of these cell types.

Absolute and spectral sensitivities in dark- and light-adapted Pagothenia borchgrevinki, an Antarctic nototheniid fish

Functional properties of the retina of Pagothenia borchgrevinki, an Antarctic nototheniid fish that lives beneath the 2.5-3 m thick sea-ice in water of -1.8 degrees C temperature, were analyzed electrophysiologically at Scott Base (77 degrees 50'S; 166 degrees 45'E). The waveform of the ERG was monophasic in the dark-adapted state and showed an off-response of opposite polarity in the light-adapted condition. Responses of the light-adapted retina were smaller than those of the dark-adapted eye, although both photopic and scotopic components were observed. Spectral sensitivity measured by monochromatic photostimulation at 14 different wavelengths across the 400-700-nm range showed a single maximum at 490 nm. The spectral sensitivity curve is consistent with a rhodopsin photopigment. The dark-adapted retina exhibited a photon flux density threshold of approximately 2 x 10(9) photons cm-2 s-1) when monochromatic flashes of 500 nm wavelength and 250 ms duration were used. When the stimulus consisted of 1 s white light, a minimum energy flux density of approx. 2 x 10(-4) microW/cm2 was necessary to elicit a detectable response. It was concluded that the visual system of P. borchgrevinki was in tune with the dominant downwelling spectral irradiance and that, due to retinal thermal noise reduction in the cold environment, no great need for particular anatomical adaptations to further enhance sensitivity existed.

Mothers' low care in the development of alexithymia: a preliminary study in Japanese college students

We examined the influences of perceived parental bonding on scores on alexithymia in a sample of 232 college students. Ratings on mothers' care, a scale of the Parental Bonding Inventory were significantly and negatively correlated with scores on the Toronto Alexithymia Scale, and also with ratings on Difficulty Describing Feelings but not Difficulty Identifying Feelings and Externally Oriented Thinking. These results were replicated in another sample of 156 college students. Although our findings were based on simple correlations, they suggest that perceived mothers' low care is related to adults' scores on alexithymia, in particular, the construct, Difficulty Describing Feelings.

Effects of job strain on helper-inducer (CD4+CD29+) and suppressor-inducer (CD4+CD45RA+) T cells in Japanese blue-collar workers

BACKGROUND

The effects of job strain on helper-inducer (CD4+CD29+) T cells and suppressor-inducer (CD4+CD45RA+) T cells are not clear.

METHODS

The subjects were 65 male blue-collar workers in a chemical plant in Japan. Perceived job stressors were assessed using the Japanese version of Job Content Questionnaire, i.e., job demands, job control, supervisor support and coworker support. Blood samples were taken from these subjects, and number and percentage of total lymphocytes were calculated for total T cells, helper (CD4+) T cells, suppressor/cytotoxic (CD8+) T cells, helper-inducer (CD4+CD29+) T cells and suppressor-inducer (CD4+CD45RA+) T cells using the double-staining fluorescence.

RESULTS

Job control significantly and positively correlated with number and percentage of helper-inducer (CD4+CD29+) T cells, after controlling for age, number of cigarettes per day and blood lead concentration (Spearman's partial correlation, p < 0.05), while job demands, supervisor support or coworker support did not (p > 0.05). The job strain index, i.e., the ratio of job demands to job control, significantly and negatively correlated with the percentage of helper-inducer (CD4+CD29+) T cells (p < 0.05). None of the job stress scales significantly correlated with number or percentage of suppressor-inducer (CD4+CD45RA+) T cells (p > 0.05).

CONCLUSIONS

It is suggested that higher job strain or lower job control is associated with a decrease in helper-inducer (CD4+CD29+) T cells in Japanese blue-collar workers.

Regulation of the function of eosinophils and basophils

Both eosinophils and basophils play active pathogenic roles in the inflammation associated with allergic disorders. Both types of cells share a majority of their cell surface structures, and because of these common surface molecules, both cells can be stimulated with a single ligand simultaneously. The growth of both types of cells is controlled by IL-3, GM-CSF, and IL-5. All three growth factors are also capable of priming both eosinophils and basophils for enhanced biological functions, such as increased mediator release and prolonged survival. Both cells express beta 2 integrins, and in contrast to neutrophils, they also express several beta 1 integrins. Ligation of these adhesion molecules also transduces the intracellular signal leading to regulation of the cellular functions. In this review, we briefly describe the effects of various ligands of surface receptors and several pharmacological compounds on the functions of human eosinophils and basophils.

Changes in natural killer cell subpopulations in lead workers

To investigate the effects of lead on human immune system, we analyzed T cell subpopulations (CD4+, CD8+ and CD3+ cells), natural killer (NK) cell subpopulations (CD16+ and CD57+ cells) and B (CD19+) cells in peripheral blood in 29 male lead workers. All were engaged in manufacturing lead stearate in a chemical factory. They were aged 23-74 (mean 49) years. Their blood lead concentrations (PbB) were between 7 and 35 (mean 18) micrograms/dl. They were divided into two groups according to their PbB: a high-PbB group (> or = 20 micrograms/dl), and a low-PbB group (< 20 micrograms/dl). The control group consisted of 19 "healthy" male workers without a history of occupational exposure to lead or to other hazardous substances, aged 48-67 (mean 58) years. The number and percentage of CD16+ cells in the high-PbB group were significantly lower than those in the controls and in the low-PbB group. There was significant negative correlation between the number of CD16+ cells and PbB in the lead workers. The percentage of CD8+ cells in the high-PbB group was larger than that in the controls and in the low-PbB group. It is suggested that the CD16+ NK cell should be a major site of the effects of lead on lymphocyte subpopulations.

Increased IL-6 and IL-8 in bronchoalveolar lavage fluids (BALF) from patients with sarcoidosis: correlation with the clinical parameters

A variety of cytokines have been implicated in the pathogenesis of pulmonary sarcoidosis, but the exact roles of IL-6 and IL-8 are not yet clear. We studied these cytokine levels in BALF from patients with pulmonary sarcoidosis, idiopathic pulmonary fibrosis (IPF), systemic screlosis (SSc) with interstitial lung disease and control subjects. IL-6 and IL-8 levels were significantly elevated in sarcoidosis, IPF and SSc with interstitial lung disease compared with control subjects. Subjects with sarcoidosis had significantly increased levels of both cytokines compared with controls when the cytokine values were corrected by the total albumin content and the two cytokine levels correlated with each other (r = 0.876). BALF IL-6 levels correlated with percent lymphocytes and percent CD3+ cells. Moreover, when sarcoidosis patients were divided into three groups, those who needed steroid therapy or had progressive disease showed increased cytokine levels in BALF over stable or improved patients. These observations suggest that locally derived IL-6 and IL-8 were increased in sarcoidosis and correlated with activity of this granulomatous lung disease.

Effect of luteinizing hormone-releasing hormone analogs on the rat ovarian follicle development

Our objective was to study the direct action of luteinizing hormone-releasing hormone (LHRH) agonist buserelin and LHRH antagonist Cetrorelix (SB-75) on cell proliferation and differentiation in the rat ovarian follicle. Preovulatory follicles were isolated from PMSG-primed immature rats and incubated in the presence or absence of hCG (10 IU/ml), buserelin (10(-9)-10(-6) M) or Cetrorelix (10(-9)-10(-6) M) for 12 h in vitro. Buserelin induced meiotic maturation of the follicle-enclosed oocytes dose-dependently. The percentage of oocytes with germinal vesicle breakdown at 10(-6) M buserelin (73.3%) did not differ from that of hCG-treated control (73.3%). Buserelin also significantly stimulated prostaglandin E2 and progesterone production by follicles, but not estradiol production. Granulosa cells were obtained from the preovulatory follicles and cultured for 5 days. Epidermal growth factor (EGF) stimulated granulosa cell growth at concentrations of 1, 10 and 100 ng/ml. In contrast, both buserelin and Cetrorelix inhibited granulosa cell growth dose-dependently in the range of 10(-10)-10(-5) M, with Cetrorelix inducing a greater growth inhibition than buserelin. Electrophoretic analysis of genomic DNA extracted from granulosa cells treated with 10(-6) M concentration of either LHRH analog revealed a definitive ladder pattern of oligonucleosomal length DNA fragments characteristic of apoptosis. Western blotting detected that EGF-induced tyrosine phosphorylation was not affected by either analog. These results demonstrate that LHRH agonist and antagonist inhibit directly proliferation of granulosa cells through apoptosis, without interference with EGF receptor phosphorylation, whereas LHRH agonist stimulates cell differentiation in the preovulatory follicle.

Effects of a combination of an antibacterial agent (ofloxacin) and a collagenase inhibitor (FN-439) on the healing of rat periapical lesions

To investigate the effects of a combination of an antibacterial agent (ofloxacin) and a collagenase inhibitor (FN-439) in the root canal treatment of apical periodontitis, we studied the healing process of experimentally induced periapical lesions in rats by using immunohistochemical methods. With a topical application of a combination of ofloxacin and FN-439 following experimentally induced periapical lesions, both neutrophils and macrophages became significantly decreased in number, while active cementogenesis and extensive bone formation were seen in the periapical region. However, the use of ofloxacin alone also demonstrated a beneficial effect on periapical inflammation and healing. Therefore, it is suggested that ofloxacin is powerful against bacterial infection whether FN-439 is added. The only observed effect of a combination of ofloxacin and FN-439 is that it may more effectively inhibit osteoclastic bone resorption and activate the remodeling of the apical periodontal tissue if this combined medicament is used in a stage of active bone destruction characterized by high production of tissue collagenase.

Acceleration of EEG theta wave precedes the phasic surge of arterial pressure during REM sleep in the rat

We investigated temporal relationships among EEG theta frequency, eye movement (EM) burst and phasic surge of arterial pressure (AP) during rapid eye movement (REM) sleep in six rats. Changes in EEG theta frequency, EM number, mean AP (MAP) and heart rate (HR) during 1 s bins were obtained with reference to the onset of the EM bursts. The acceleration of EEG theta frequency preceded both the EM burst and the phasic increases of AP. The increase of MAP was closely correlated with the theta frequency but not the EM number during the period of EM burst. The possible involvement of the limbic system for the generation of phasic surge in AP during REM sleep is discussed.

Successful laparoscopic management of primary abdominal pregnancy

Overall, approximately 1% of ectopic pregnancies are abdominal pregnancies, which can be life-threatening even when surgical intervention with laparotomy is performed. We present a case in which abdominal pregnancy was successfully managed by operative laparoscopy. A 25 year old Japanese woman presented 6 weeks after her last menstruation with elevated basal body temperature, lower abdominal pain, and light vaginal bleeding. The urinary human chorionic gonadotrophin (HCG) concentration was 2137 IU/I, and laparoscopic findings (i.e. the implantation site was the posterior serosa of the uterus with normal adnexae) established a diagnosis of primary abdominal pregnancy. The gestational product was completely removed by laparoscopic surgery with no uncontrollable loss of blood. The urinary concentration of HCG declined rapidly and the patient made an uneventful recovery. Operative laparoscopy is a safe alternative for the management of appropriately selected patients with early abdominal pregnancy.

[A case suspected of early active pulmonary tuberculosis detected by CT with the onset of episcleritis]

A 56-year-old female with the chief complaint of conjunctival injection was referred to our hospital after treatments with oral and topical corticosteroid under the diagnosis of episcleritis without any therapeutic efficacy. Possible causes of the episcleritis such as collagen vascular disease were not found, but a chest CT revealed centrilobular nodules, branching linear lesions and bronchial wall thickening which were not detected in a plain X-ray picture. We suspected pulmonary tuberculosis and tuberculous episcleritis based on these CT findings, strongly positive tuberculine skin test result and a history of contact with a smear positive tuberculosis patient. The pulmonary lesion disappeared and the episcleritis healed after the treatment with systemic antituberculous agents.

Pharmacologic study of basophil histamine release induced by monocyte chemotactic protein-1 with kinase inhibitors

Monocyte chemotactic protein-1 (MCP-1)/monocyte chemotactic activating factor has a potent histamine-releasing activity for basophils and is a major component of IgE-independent histamine-releasing factors (HRF). In this study, we examined the effect of a panel of kinase inhibitors on MCP-1-induced histamine release from human basophils to characterize the signaling pathway used by this chemokine. Genistein (3 micrograms/ml), an inhibitor of tyrosine kinase, inhibited MCP-1-induced histamine release by 44%. Wortmannin is a specific inhibitor of phosphatidylinositol 3 kinase (PI-3 kinase). It blocked MCP-1-induced histamine release with an IC50 of 3.3 x 10(-8) M indicating a role of PI-3 kinase in this reaction. KT5926, an inhibitor of myosin light chain kinase, also inhibited histamine release in response to MCP-1 with an IC50 of 10(-6) M. Staurosporine, a potent inhibitor of protein kinase C, although being not specific, augmented MCP-1-induced histamine release by 31.9% at 10(-6) M. These results indicate the possible involvement of a series of kinases, including PI-3 kinase, in the signal transduction pathway used by MCP-1.

The crystal structure of lipase II from Rhizopus niveus at 2.2 A resolution

The crystal and molecular structure of Lipase II from Rhizopus niveus was analyzed using X-ray single crystal diffraction data at a resolution of 2.2 A. The structure was refined to an R-factor of 0.19 for all available data. This lipase was purified and crystallized as Lipase I, which contains two polypeptide chains combined through non-covalent interaction. However, during crystal growth, Lipase I was converted to Lipase II, which consists of a single polypeptide chain of 269 amino acid residues, by limited proteolysis. The structure of Lipase II shows a typical alpha/beta hydrolase fold containing the so-called nucleophilic elbow. The catalytic center of this enzyme is analogous to those of other neutral lipases and serine proteases. This catalytic center is sheltered by an alpha-helix lid, which appears in neutral lipases, opening the active site at the oil-water interface.

In situ detection of platelet-derived growth factor-A and -B chain mRNA in human coronary arteries after percutaneous transluminal coronary angioplasty

Experimental studies have shown that platelet-derived growth factor (PDGF) plays a role in wound-healing processes after angioplasty. In humans, after percutaneous transluminal coronary angioplasty (PTCA), this has not yet been documented. Six coronary arteries of five patients who died after PTCA were studied. The angioplasty sites were sliced serially, and the slices were studied using immunocytochemistry and in situ hybridization. Monoclonal antibodies were directed against muscle actin, vimentin, macrophages, and endothelium. In situ hybridization was performed using a synthetic oligonucleotide probe complementary to the PDGF-A and -B chain mRNAs. The identification of cells was based on a comparison with immune-stained sections. Positive autoradiographic signals for PDGF-A and -B chain mRNAs were found at the site of the PTCA injury and related to areas that contained macrophages, spindle cells, smooth muscle cells, and endothelial cells of neovascularization. In humans, both PDGF-A and -B chain mRNAs are expressed at sites of PTCA injury. The expression relates to the reparative response, and it appears that the cells involved are macrophages, spindle cells, smooth muscle cells, and endothelial cells of neovascularization. This is the first study to document the expression of PDGF-A and -B mRNAs at sites of repair in human coronary arteries after PTCA. It suggests strongly that PDGF is involved in the repair process after PTCA.

[Multicystic encephalopathy with frontal lobe-originated gelastic seizure, ipsilateral oculogyric crisis, and horizontal epileptic nystagmus: an autopsy case]

Attacks of gelastic (laughing) seizure are usually reported as complex partial seizures of temporal lobe epilepsy and seizures associated with hypothalamic hamartomas, but are rarely reported as complex partial seizures of frontal lobe origin. We recently encountered a 29-year-old woman who had gelastic seizure attacks from age 17. She had shown severe mental retardation with cerebral palsy at 7 months, and entered precocious puberty at age 7. Attacks of gelastic seizure with ipsilateral adversive seizures, ipsilateral oculogyric crisis, and horizontal epileptic nystagmus were observed until her death at age 29. Each gelastic seizure lasted 1 to 10 minutes. Her laughing was very strong and loud. Interictal spikes were observed over the right fronto-parietal lobe, but no ictal spike was detected. The neuropathological examinations of her brain revealed no hypothalamic lesions such as hamartomas, gliosis, and distinct neuronal loss. Her brain was severely affected with multicystic encephalopathy, and the bilateral temporal lobe tissues were almost replaced by the cystic changes. The right frontal lobe and occipital lobe were not cystic. From the clinicopathological examinations, the focus of her gelastic seizure was considered to be of the right frontal origin. The hippocampus and parahippocampal gyrus are major components of the limbic system, which is involved in affective emotions. Although the right hippocampus and parahippocampal gyrus were completely lost, and those of the left hemisphere were almost completely lost, by the multicystic replacements in this case, the gelastic seizure attacks were evoked from right frontal origin. The frontal lobe may play an important role in motor expressions of laughing. The motor expressions of the loud and strong laughing may be one of the characteristic features of frontal lobe-originated gelastic seizure of this case.

[Changes in symptoms after the great Hanshin Earthquake in patients with dementia]

Factors related to changes in symptoms after the great Hanshin Earthquake in patients with dementia were studied. Interviews were conducted with family members of thirty patients given the diagnosis of dementia at the Center for Elderly Dementia of Hyogo College of Medicine between August 1993 and December 1994. The earthquake occurred on January 17, 1995, and the interviews were conducted three months later. Patients were classified into two groups: Group 1: those whose symptoms changed after the earthquake (n = 13); Group 2: those whose symptoms did not change after the earthquake (n = 17). Symptoms were exacerbated within 1 week after the earthquake. The percentage of patients with mild dementia was higher in Group 1 than in Group 2. Scores on the Mini-Mental State examination and on Hasegawa's dementia scale were lower in Group 2 than in Group 1. On a modified GBS-scale, patients in Group 2 scored higher than those in Group 1 in impaired intellectual function and in reduced motivation, and they scored lower than those in Group 1 in impaired emotional function. CT scans showed that cortical atrophy and ventricular enlargement were greater in Group 2 than in Group 1. These findings suggest that after the earthquake symptoms became more severe in patients with mild dementia at an early stage, who have anxiety, irritability, and emotional lability.

The effect of okadaic acid on histamine release, cell morphology and phosphorylation in rat basophilic leukemia (RBL-2H3) cells, human basophils and rat peritoneal mast cells

To study the involvement of serine/threonine phosphatase in the signal transduction of mast cells, we examined the effects of okadaic acid (OA), an inhibitor of type-1 and -2A phosphatase on histamine release, cell morphology, calcium influx and protein phosphorylation of rat basophilic leukemia (RBL-2H3) cells, human basophils and rat peritoneal mast cells. OA inhibited IgE-mediated histamine release from RBL-2H3 cells and human basophils dose-dependently. There was a remarkable enhancement of IgE-mediated histamine release when rat peritoneal mast cells were suboptimally challenged. OA induced a marked change of cell features, detached RBL-2H3 cells from plastic well and kept the 18- and 68-kD proteins phosphorylated. These findings show that phosphatase may play a role in the modulation of secretion in mast cells.

Takayasu's arteritis associated with ulcerative colitis; genetic factors in this association

Both ulcerative colitis and Takayasu's arteritis are though to be organ-specific immune-mediated inflammatory diseases. We present the rare case of a 23-year-old woman with a 4-year history of ulcerative colitis who developed Takayasu's arteritis one month after giving birth. She was found to carry the human leukocyte antigens (HLA)-B52 and DR2, which were previously noted to be associated with these inflammatory conditions in the Japanese population. The pathogenic relevance of this haplotype to the concomitant development of these two conditions is discussed.

Interpretation of scintigraphy of papillary cystadenoma lymphomatosum (Warthin's tumor) on the basis of histopathologic findings

OBJECTIVES

The accumulation of 99mTc-pertechnetate in Warthin's tumor was estimated scintigraphically and histopathologically to determine the role of the epithelial component in scintigraphy.

STUDY DESIGN

Six cases underwent histopathologic examination and scintigraphic evaluation with 99mTc-pertechnetate. Histopathologically the tumors were classified into types according to the epithelial component and cystic space and compared with scintigraphic results evaluated by dynamic radioactive index and wash-out image.

RESULTS

Histopathologic and scintigraphic observations showed an adequate correlation. Cases with a large epithelial component and poor cystic space showed a large radioactive index of dynamic scintigraphy and hot accumulation of wash-out image.

CONCLUSION

The scintigraphic results were chiefly due to the epithelial component, but the influence of the cystic space could not be disregarded.

Nonreleasing basophils convert to releasing basophils by culturing with IL-3

The extent of basophil histamine release initiated by IgE cross-linking stimuli has been known to vary greatly among donors. Studies on anti-IgE nonreleasing basophils are useful in understanding the IgE-specific control mechanism of mediator release. We attempted to determine (1) whether a mutation of Fc epsilon RI is present in nonreleasing basophils and (2) whether treatment with IL-3 converts anti-IgE nonreleasing basophils to releasing basophils. Basophils were purified from normal human blood and donors were divided into releasers (maximal histamine release > 5%) and nonreleasers (< 5%). The mutation of Fc epsilon RI alpha, beta, and gamma was evaluated by reverse transcriptase-polymerase chain reaction, and the DNA sequence was determined from amplified polymerase chain reaction products. Although antibodies against Fc epsilon RI failed to cause histamine release in anti-IgE nonreleasing basophils, no primary structural change of Fc epsilon RI was observed in nonreleaser basophils. After culturing with IL-3 for 7 days, nonreleasing basophils released histamine in response to anti-IgE, and dose-response curves of anti-IgE were equal in both releasers and nonreleasers. The conversion of nonreleasing basophils to releasing basophils was evident after 3 days of culture with IL-3. These findings indicate that nonreleasing basophils have recoverable defect(s) in the signal transduction pathway after IgE cross-linking.

Substrate specificity of a novel serine protease from soybean [Glycine max (L.) Merrill]

The substrate specificity of a novel serine protease isolated from soybean seeds, cultivar Keburi, was investigated using various peptide-MCAs and several neuropeptides involving single and paired basic amino acid sequences. The protease was quite specific for arginine residue at the P1 site of the active center, and it recognized paired Arg-Arg and cleaved at the linkage between Arg-Arg or after Arg-Arg in peptide and protein molecules. This is the first protease in plant tissues which resembles in substrate specificity the arginine-specific serine proteinases from porcine gastric and intestinal mucosa, recognizing paired basic amino acid sequences.