[Immunocytochemical study of CuZn superoxide dismutase in the myocardium of normal subjects and patients of rheumatic heart disease]

Using the methods of immunocytochemistry and immune electron microscopy, we studied the subcellular localization of GuZn superoxide dismutase (CuZn SOD) in the myocardium of 8 normal subjects and the changes of CuZn SOD of the myocardium in 51 patients of rheumatic heart disease, and at same time, we also determined the CuZn SOD contents in the myocardium with radioimmunoassay. This study demonstrated that most normal myocardial cells contained CuZn SOD. The ventricular myocardial cells stained somewhat stronger than the atrial myocardial cells. CuZn SOD was mainly distributed in the cytoplasm and the nucleus, less in mitochondria, a little in lysosomes and almost no gold particle was seen on the membranous structures of sarcoplasmic reticula and Golgi's complex. The positive level of CuZn SOD in rheumatic myocardium had remarkable correlation with myocardial fibrosis and arteriopathy and the recovery of the heart functions after valve replacement. The changes of CuZn SOD in various organelles in the myocardium of patients with rheumatic heart disease may be possibly related to the injuries of their membranous structure.

Planar defects in β-iron disilicide (β-FeSi2) analyzed by transmission electron microscopy and modeling

Microplanar defects were observed in β-iron disilicide by transmission electron microscopy. They were identified as (100)[011]/2 intrinsic stacking faults by means of electron diffraction patterns and observed in high-resolution lattice images. A structural model of the faults is proposed here in setting the defect position at x = ¼ within the cell.

Protective effect of nedocromil sodium on the IL1-induced release of GM-CSF from cultured human bronchial epithelial cells

Cultured human bronchial epithelial cells constitutively produce granulocyte-macrophage colony-stimulating factor (GM-CSF). The synthesis and release of GM-CSF is upregulated in bronchial epithelium of patients with symptomatic asthma and this may contribute to the local activation of inflammatory cells in their bronchial mucosa. The cause of this upregulation of GM-CSF expression is unknown, but an increased release of interleukin-1 (IL1) from other airway resident cells might be involved, as an increase in GM-CSF production can be induced in vitro in normal bronchial epithelial cells by IL1 and the airway secretions of asthmatics contain high amounts of this cytokine. In the present study, we have evaluated the effect of the anti-inflammatory and antiasthmatic drug, nedocromil sodium, on the spontaneous and IL1-induced expression of GM-CSF in cultured bronchial epithelial cells. This compound, at the concentration of 10(-5) M, reduced the IL1-induced increase in GM-CSF release from epithelial cells by more than 40%, but it did not affect the constitutive production of GM-CSF.

Coping in panic and major depressive disorder. Relative effects of symptom severity and diagnostic comorbidity

This study used the Ways of Coping Checklist to examine coping style in patients with panic and major depressive disorders. The relative contribution of distress (symptom severity) and diagnostic comorbidity was determined in three sets of diagnostic subgroups: patients suffering from both panic and major depressive disorders (compared with either disorder alone); panic patients with and without agoraphobia (regardless of concurrent depression); and patients with versus without a concurrent axis II personality disorder. Use of less problem-focused and more emotion-focused coping was strongly correlated with level of distress and was associated with all three examples of diagnostic comorbidity when level of distress was used as a covariate. Regression analyses showed that, except for the presence of a personality disorder, distress was a much stronger predictor of coping than diagnostic subtype.

Thickness-shear mode shapes and mass-frequency influence surface of a circular and electroded AT-cut quartz resonator

Finite-element solutions for the fundamental thickness shear mode and the second-anharmonic overtone of a circular, 1.87-MHz AT-cut quartz plate with no electrodes are presented and compared with previously obtained results for a rectangular plate of similar properties. The edge flexural mode in circular plates, a vibration mode not seen in the rectangular plate is also presented. A 5-MHz circular and electroded AT-cut quartz plate is studied. A portion of the frequency spectrum is constructed in the neighborhood of the fundamental thickness-shear mode. A convergence study is also presented for the electroded 5-MHz plate. A new two-dimensional (2-D) technique for visualizing the vibration mode solutions is presented. This method departs substantially from the three-dimensional (3-D) ;wire-frame' plots presented in the previous analysis. The 2-D images can be manipulated to produce nodal line diagrams and can be color coded to illustrate mode shapes and energy trapping phenomenon. A contour plot of the mass-frequency influence surface for the plated 5-MHz resonator is presented. The mass-frequency influence surface is defined as a surface giving the frequency change due to a small localized mass applied to the resonator surface.

Liposome-encapsulated hemoglobin processing methods

An effective and safe red blood cell substitute is being developed based on double emulsion/evaporation techniques followed by high pressure homogenization to form liposome-encapsulated hemoglobin (LEH). Formulations are made up of hydrogenated phosphatidylcholine (PC, soy or egg), cholesterol, phosphatidylinositol (PI), and alpha-tocopherol in a molar ratio of 1:1:0.2:0.02, respectively. Resulting LEH-encapsulated hemoglobin (Hb) concentrations are greater than 80% of precursor Hb solutions. Met-Hb generation accompanying LEH processing appears to be small with only a 3% increase for encapsulated over precursor. These results correspond to an oxygen content for an LEH suspension sample (50% by volume LEH) of 15 volume% oxygen. Oxygen affinity and cooperativity values for LEH suspensions appear to be near the normal values expected for whole blood. The viscosity of LEH suspension samples (50% by volume LEH in phosphate-buffered saline containing 7.5 wt% albumin) were slightly higher than that of whole blood. The effect of shear rate on leakage of encapsulated Hb from LEH was small, i.e. 0.5% or less. Nearly total isovolemic exchange transfusion using a cannulated rat model demonstrates efficacy of LEH suspension samples. There appears to be no difference in rat internal organ weights between rats exchanged with control compared to rats exchanged with LEH. Circulation half-life following 50% isovolemic exchange-transfusion is about 15 to 18 hours.

Determination of dietary cadmium-induced metallothioneins in rabbit kidneys and cadmium in metallothioneins by anion-exchange high-performance liquid chromatography coupled with graphite furnace atomic absorption spectrometry

A rapid method is described for the determination of dietary cadmium-induced metallothioneins (MTs) in rabbit kidneys by anion-exchange high-performance liquid chromatography. Rabbit kidney MT-I and MT-II were eluted at ca. 15.0 and 18.8 min, respectively, from a DEAE-5PW anion-exchange column with a Tris-HCl buffer (0.01-0.25 M, pH 8.6) and detected by ultraviolet absorbance at 254 nm. A standard calibration curve was constructed using purified standard MT isoforms, which demonstrated an excellent linear correlation between UV absorbance peak heights and the amounts of MT isoforms. Feeding a dose of cadmium for some days resulted in an increase in MT concentrations in rabbit kidneys, but not in the livers. The cadmium concentrations in MT-I and MT-II elutions were determined by graphite furnace atomic absorption spectrometry. MT-I and MT-II showed some differences associated with the oral intake of cadmium. Dietary cadmium also caused zinc to accumulate in kidneys to some extent. The effects of dietary oleic acid on the synthesis of MTs were also studied. Based on the method of standard additions, the recovery of MTs exceeded 93% and replicated injection of samples yielded a relative standard deviation of 2.4% at an MT level of 280 micrograms/g.

Gene expression of tyrosine hydroxylase and neuropeptide Y in prevertebral ganglia of renal hypertensive rats

The gene expression of tyrosine hydroxylase (TH) and neuropeptide Y (NPY) was studied in prevertebral ganglia and adrenal glands of adult male rats during the development of renal hypertension (removal of 1 kidney/constriction of other kidney). Only tissues from rats with arterial pressures significantly elevated by day 3 were compared with those from controls. At 4 or 5 days after renal surgery, superior cervical ganglia, celiac-mesenteric plexus, adrenal glands, and stellate ganglia were surgically removed from nonfixed rats for Northern blot analysis or from perfusion-fixed rats for in situ hybridization. In all tissues, levels of TH mRNA were decreased in hypertensive rats; cells with decreased levels were scattered throughout each tissue. In contrast, levels of NPY mRNA were unchanged in hypertensive rats compared with controls. Changes in TH mRNA levels suggest that the developing phase of renal hypertension is associated with a decrease in sympathetic outflow to the periphery. In contrast, the failure of NPY mRNA levels to change suggests a different regulatory mechanism for NPY expression or a different role for NPY in sympathetic neurotransmission.

[The effects of sodium butyrate (NABT) on fibrillar centres and Ag-staining protein of nucleolus of human stomach glandular carcinoma (MGC-803) cells]

The changes in the ultrastructure of fibrillar centres, morphological type of nucleolus, and the content of Ag-nucleolus protein of Sodium Butyrate treated MGC-803 cells have been studied. It was found that the number of fibrillar centres and Ag-staining granules, content of Ag-staining protein of nucleolus were decreased, and nucleolar morphological type was changed from reticulated to ring-shaped in NaBT treated MGC-803 cells. These results indicate that NaBT regulate the proliferation and differentiation of cells by inhibiting rRNA synthesis and rDNA transcriptional activity.

[Hemoglobin phenotype of native residents in Tibet and structural analysis of HbE]

In this paper, the hemoglobin phenotype of 3,711 cases of native residents (Tibetan, 3,451 cases; Menba, 148 cases and LuoBa ethnic group, 122 cases) and 478 cases of immigrants. (totalling 4,190 cases), in 3 different sea-levels of the Autonomous Region of Tibet (Naqu-Ando, Lhasa-Rikeze and Lingzhi districts), are described. 11 cases (1 case in Tibetan, 6 cases in MenBa and 4 cases in LuoBa ethnic group) of slow-moving abnormal Hb were found. The mean incidence of abnormal Hb in the native residents was 2.98/1000. The incidence in MenBa and LuoBa ethical groups was remarkably higher than that in Tibetan. Besides, the Hb phenotypes of native residents were HbA, HbA2 and HbF. Structural analysis of the abnormal Hb by micro-crystal cellulose membrane and high performance liquid chromatography (HPLC) demonstrated that all the 11 cases of Hb variant in the native residents are HbE [ beta 26 (B8) Glu----Lys]. The distribution and characteristics of the abnormal Hb in Tibet are discussed.

DNA adducts as early bioindicators of chemical exposure

Sensitive analytical methods indicate the presence of hundreds of chemical contaminants in our environment. However, concentration of these pollutants is usually at the low parts per million or parts per billion level. At such low levels, toxicants induce long-term (chronic) rather than short-term (acute) toxicities. Experiments are designed to evaluate chronic toxicity using early bioindicators. Recently, fish have been used as experimental animals because some species show early (weeks as opposed to years in other research animals), sensitive responses. Thus, medaka (Oryzias latipes), following exposure to diethylnitrosamine (DEN), exhibited liver tumors in several weeks; more interestingly its DNA was modified (to a 'DNA-adduct') after only 24-48 hours exposure. Such adducts show promise as early bioindicators because they are formed within hours of exposure. The formation of DNA-adducts were monitored in medaka and rainbow trout (Salmo gairdneri) exposed to DEN by aqueous or intra-peritoneal routes. Using HPLC-Fluorimetry, O (6)-ethylguanine (O (6)-EtGua) was detected and monitored in acid thermal hydrolysates of DNA isolates. (Detection limit for O (6)-EtGua was as low as 3 ng, 1.7×10(-11) moles). Fourier transform cyclotron resonance mass spectrometry with IR laser desorption/ionization was used advantageously to establish the structure of nucleotides, bases and nucleosides directly, without further cumbersome derivatizations. Other aspects of DNA-adducts are discussed.

Conformations of IgE bound to its receptor Fc epsilon RI and in solution

Previous resonance energy transfer studies suggested that murine immunoglobulin E (IgE) is bent near the junction of its Fc and Fab segments when bound to its high-affinity receptor (Fc epsilon RI) on RBL cells. To examine further the conformations of IgE, both bound to this receptor and in solution, a mutant recombinant IgE (epsilon/C gamma 3*) was prepared that has a cysteine replacing a serine near the C-terminal ends of the heavy chain. The introduced cysteine residues provide a means for specific modification of IgE, and the sulfhydryl groups were selectively labeled with fluorescein-5-maleimide (FM-epsilon/C gamma 3*). This IgE also binds a 5-(dimethylamino)naphthalene-1-sulfonyl (DNS) group in the antigen-binding sites. Resonance energy transfer experiments carried out on receptor-bound FM-epsilon/C gamma 3* yielded a distance of 53 A between fluorescein near the C-terminal end of the Fc segment and amphipathic acceptor probes at the membrane surface. The average distance between this C-terminal fluorescein and acceptor eosin-DNS in the antigen-binding sites at the N-terminal ends of the Fab segments was found to be 69 A. These results combine with those from previous structural studies to provide an unprecedented detailed description of the bent geometry of IgE bound to its receptor on the membrane. Energy transfer measured for FM-epsilon/C gamma 3* in solution between fluorescein near the C-terminal end of the Fc segment and eosin-DNS at the N-terminal ends of the Fab segments indicates that the average distance between these probes is about 71 A.(ABSTRACT TRUNCATED AT 250 WORDS)

Polarization pinhole interferometer

A polarization pinhole interferometer is based on the principles of pinhole diffraction, a common light path, and the polarization technique in its design. It has many advantages, such as adjustable contrast of the fringes, nondestructive testing, and less sensitivity to environmental factors. The instrument can be used extensively in optical element testing and glue-layer testing. The accuracy of the fringe pattern analysis is controlled by the number of sampled points in the fringes. The analysis results of the closed fringe pattern are given.

Stunned left ventricular myocardium after exercise treadmill testing in coronary artery disease

Myocardial stunning (postischemic ventricular dysfunction) occurs in dogs after coronary stenosis following treadmill exercise. Less data are available in humans regarding development of stunned myocardium after exercise. Regional wall motion changes were evaluated in 22 patients with known coronary artery disease using 2-dimensional echocardiography and exercise treadmill testing. Wall motion was scored as 1 = normal, 2 = hypokinetic, 3 = akinetic, 4 = dyskinetic. At least 1 left ventricular segment with normal resting function developed an increase in wall motion score at 15 or 30 minutes compared with values at rest. The wall motion score in the midportion of the ventricular septum increased from 1.0 at rest to 1.6 (p less than 0.004) at 30 minutes after exercise; the basal inferior wall score worsened from 1.0 at rest to 1.9 (p less than 0.01) at 30 minutes after exercise. Coronary angiographic data in these patients revealed that left anterior descending narrowing correlated best with left ventricular septal wall motion abnormalities, whereas right coronary artery and circumflex narrowing best correlated with inferior and posterior wall motion abnormalities. Eight normal adult volunteers with no history of myocardial ischemia also underwent 2-dimensional echocardiography and exercise testing. No wall motion abnormalities were observed at any time after exercise. The present study suggests that in patients with coronary artery disease, exercise treadmill testing may induce regional wall motion abnormalities of the left ventricle that persist greater than or equal to 30 minutes after exercise, an observation consistent with the phenomenon of stunned myocardium.

Are the post-inspiratory neurons in the decerebrate rat cranial motoneurons or interneurons?

We examined the membrane potentials of 63 respiratory neurons in the ventrolateral medulla of decerebrate rats, whose trajectories had the characteristics of the post-inspiratory neurons, i.e. exhibiting hyperpolarization during inspiration, rapid depolarization at end-inspiration and progressive repolarization with a decrementing pattern during the intervals between phrenic bursts. Synaptic responses of 6 post-inspiratory neurons which were tested by stimulation of cervical vagus or superior laryngeal nerves were excitatory. Eleven of these 63 post-inspiratory neurons were labeled by intracellular injection of horseradish peroxidase (HRP). Ten of these 11 labeled neurons were motoneurons since their axons exited the medulla after joining the roots of cranial nerves. However, only one of these motoneurons was antidromically activated by stimulation of the ipsilateral cervical vagus nerve. We assumed that most of the post-inspiratory medullary neurons of the present study were motoneurons, but not interneurons, although antidromic invasion was not possible after stimulation of the cervical vagus and superior laryngeal nerves. Two post-inspiratory neurons of this sample had bulbospinal axons, which were revealed by antidromical activation of spinal cord and HRP labeling, respectively. The axon of the labeled bulbospinal neuron had axonal collaterals which were distributed within the region of the nucleus ambiguous of the ipsilateral medulla. The functional significance of this type of post-inspiratory neuron is discussed.

[Role of nucleus parabrachialis medialis in the "renzhong" induced pressor response in rabbits]

Experiments were performed on 18 rabbits, bivagotomized, gallamine triethiodide immobilized and artificially ventilated. The effects of electrical stimulation of "renzhong" (Du 26) area and NPBM, separately and simultaneously, on arterial blood pressure and heart rate were observed before and after electrolytic or chemical lesion of NPBM. Electrical stimulation of "renzhong" area or NPBM, separately could elicit an increase in arterial blood pressure; when both "renzhong" and NPBM were stimulated, the pressor response to NPBM stimulation could affect that of "renzhong" area's. But after electrolytic or chemical lesion of NPBM, stimulation of NPBM could no longer elicit pressor response. On the other hand, the pressor response induced by electrical stimulation of "renzhong" area decreased obviously, after lesion of NPBM or transection of brain stem between NPBM and Nucleus trigemini principalis. These results suggest that NPBM might take part in the pressor response of "renzhong" area stimulation.

Osmotic potential of media affecting green plant percentage in wheat anther culture

The percentage of green plants in anther culture is known to be controlled by the genetics of anther donor materials. The objective of this study was to determine whether components in the culture media also would have a significant influence on the percentage of green plants from wheat anther culture. Anthers of a spring wheat cultivar, "Pavon 76", were cultured on potato 4 (P4) induction media with various modifications. Addition of 200 g/l ficoll to the liquid P4 medium significantly increased the percentage of green plants even though the final yield of green plants per 100 anthers was lower than the liquid medium. A higher concentration of maltose (135 g/l) produced significantly higher percentage of green plants than the medium containing 90 g/l maltose or sucrose. These results demonstrate culture medium effects on albinism, indicating that the percentage of green plants in wheat anther culture can be increased by optimizing medium osmotic potential.

Gamma-tubulin is present in Drosophila melanogaster and Homo sapiens and is associated with the centrosome

The mipA gene of A. nidulans encodes a newly discovered member of the tubulin superfamily of proteins, gamma-tubulin. In A. nidulans, gamma-tubulin is essential for nuclear division and microtubule assembly and is associated with the spindle pole body, the fungal microtubule organizing center. By low stringency hybridizations we have cloned cDNAs from D. melanogaster and H. sapiens, the predicted products of which share more than 66% amino acid identity with A. nidulans gamma-tubulin. gamma-Tubulin-specific antibodies stained centrosomes of Drosophila, human, and mouse cell lines. Staining was most intense in prophase through metaphase when microtubule assembly from centrosomes was maximal. These results demonstrate that gamma-tubulin genes are present and expressed in humans and flies; they suggest that gamma-tubulin may be a universal component of microtubule organizing centers; and they are consistent with an earlier hypothesis that gamma-tubulin is a minus-end nucleator of microtubule assembly.

Patterns of membrane potentials and distributions of the medullary respiratory neurons in the decerebrate rat

We analyzed the membrane potential of 161 respiratory neurons in the medulla of decerebrate rats which were paralyzed and ventilated. Three types of inspiratory (I) neurons were observed: those displaying progressive depolarization in inspiration (augmenting I neurons), those which gradually repolarized after maximal depolarization at the onset of inspiration (decrementing I neurons) and those exhibiting a plateau or bell-shaped membrane potential trajectory throughout inspiration (I-all neurons). Three types of expiratory (E) neurons were also encountered: those in which the membrane potential progressively depolarized (augmenting E neurons), those in which the membrane potential repolarized during the interval between phrenic bursts (decrementing E or post-I neurons) and those exhibiting a plateau or bell-shaped membrane potential trajectory throughout expiration (E-all neurons). Axonal projections of these medullary neurons were identified in the cranial nerves (n = 34), or in the spinal cord (n = 19) as revealed by antidromic stimulation and/or by reconstruction following horseradish peroxidase (HRP) labeling. The other 108 neurons were not antidromically activated (NAA) by the stimulations tested, or had their axons terminating inside the medulla as revealed by HRP labeling. All these respiratory neurons, except for 3 which were hypoglossal motoneurons, had their somata within the ventrolateral medulla, in the region of the nucleus ambiguus, homologous to the ventral respiratory group (VRG) of the cat. No dorsal respiratory group (DRG) was detected within the medulla of the rats. Due to this absence of a DRG, it is concluded that the neural organization of respiratory centers is quite different in cats and rats.

Tardive dyskinesia in the mentally retarded: comparison of prevalence, risk factors and topography with a schizophrenic population

Thirty mentally retarded patients treated with neuroleptics for aberrant behavior were compared with 30 neuroleptic-treated schizophrenics for the presence, topography and risk factors associated with tardive dyskinesia (TD). In the total sample (n = 60), female sex, schizophrenic diagnosis and increasing age were associated with TD. The length of neuroleptic treatment and current neuroleptic dose were not significantly associated with TD. The only topographical difference in TD presentation was that the mentally retarded group had significantly more tongue involvement.

[Plasma estrogen level in patients with cervical cancer]

Plasma estrone (E1), estradiol (E2) and estriol (E3) levels were determined in 51 cases of cervical cancer and 52 normal postmenopausal women. It was found that the plasma E1, E2 and E3 levels in cervical cancer patients were higher than those in normal postmenopausal women. There was a significant difference in E1 and E3 between the two groups (P less than 0.05). E1/E2, E2/E3, E1/E3 and E1/E2 + E3 were measured in the two groups. E1/E2 ratio in cervical cancer patients was higher than that in normal postmenopausal women (P less than 0.05).

[Mechanisms of effects of electrical stimulation of "Renzhong" (Du 26) on phrenic discharge in rabbits]

Experiments were performed on urethane anesthetized, bivagotomized, flaxedil paralyzed and artificially ventilated rabbits. The effects of stimulation of "Renzhong" (Du 26) on phrenic discharge were not caused secondarily by blood pressure alteration. The effects were abolished by bilateral section of infraorbital nerves, were similar to those of stimulation of the central end of the infraorbital nerve, and were not qualitatively changed by mid-colliculi decerebration. The responses of the bulbar respiratory related neurons were coordinated with those of the phrenic nerve to stimulation of "Renzhong", i.e., the responses of almost all of the inspiratory neurons were consistent with phrenic responses and those of the most of the expiratory neurons were contrary to them. It can be concluded that the effects of electrical stimulation of "Renzhong" on phrenic discharge result from the nervous reflex. Its afferent is infraorbital nerve and the higher centers are not essential for it. The bulbar respiratory related neurons might play an important part in it.

Differential expression of estrogen-regulated CD4 and Ia positive cells in the immature rat uterus

Estradiol treatment of sexually immature Sprague-Dawley, Cr:NIH-nu/+ and Cr:NIH-nu/nu rats for 2 days results in a significant increase in the number of uterine eosinophils and OX-42 positive macrophages. However, only Sprague-Dawley rats exhibit an estrogen regulated increase in the number of cells expressing immunoreactive CD4 and Ia, suggesting that the differential responsiveness to the effects of estradiol between the two strains of rats may be genetically controlled. Nevertheless, Cr:NIH-nu/nu rats, which are deficient in T-cells, possess virtually identical numbers of CD4 positive staining uterine cells as compared to their nu/+ littermate controls, indicating that the expression of immunoreactive CD4 is associated with a resident non-T-cell population. In addition, a message for rat CD4 was observed in Northern blots of uterine mRNA, suggesting that the immunoreactive CD4 expressed by uterine cells is probably a fully functional cell surface antigen/receptor rather than a truncated form which only expresses the antigenic determinant recognized by the W3/25 monoclonal antibody.

No evidence for true HTLV-I or HIV-1 antibodies in Finnish Lapps

Previous seroepidemiologic studies have suggested that in addition to certain subtropical and tropical parts of the world, human T cell leukemia virus type I (HTLV-I) may be endemic in the arctic regions, too. We studied 111 sera collected from original inhabitants of Finnish Lapland with ELISA and Western blot analysis for antibodies to HTLV-I and human immunodeficiency virus type 1 (HIV-1). No true positive sera for either virus were found in the confirmatory Western blot assays, albeit 6 and 2%, respectively, were positive in the screening ELISA assays. Despite the small sample size this survey does not support the hypothesis that HTLV-I would be endemic in the Arctic.

Actively induced experimental allergic orchitis in Lewis-resistant (Le-R) rats: reversibility of disease resistance by immunization with Bordetella pertussis

Differential susceptibility to the induction of experimental allergic orchitis (EAO) was examined in Lewis/NCr and Le-R subline rats. Lewis/NCr rats were found to be fully susceptible to the induction of EAO whereas Le-R subline rats were not. Disease resistance exhibited by Le-R rats could be overcome by including Bordetella pertussis in the immunization protocol. However, reversal of resistance with B. pertussis was dependent on the dose of rat testicular homogenate in the inoculum and found to be effective only at lower doses of antigen (10 mg/rat). Disease resistance in Le-R rats as well as B. pertussis-induced reversal of resistance did not appear to be associated with either (1) a significant difference in the number of mast cells in the ductus efferentes, the anatomic location of the earliest inflammatory infiltrates, or (2) an alteration in the phenotypic expression of either innate or B. pertussis-induced sensitivity to vasoactive amines. The results are discussed in the context of the role of B. pertussis in other animal models of organ-specific autoimmune diseases. It is proposed that the phenotypic expression of resistance to EAO in Le-R rats is a result of a mutation in a common regulatory locus affecting susceptibility to multiple autoimmune diseases and whose immunoregulatory action is normally exerted during the sensitization phase of the immune response.