The role of beta-fibrinogen genotype in determining plasma fibrinogen levels in young survivors of myocardial infarction and healthy controls from Sweden

Beta-fibrinogen G/A-455 polymorphism genotype was determined in 123 young survivors of myocardial infarction and 86 healthy controls from Sweden. Frequency of the A-455 allele was 0.25 (95% Confidence Interval 0.21-0.29) in both patients and controls, significantly higher than that reported previously (0.19, 95% CI 0.16-0.22) in 292 men from the UK. Mean plasma fibrinogen level was significantly higher in patients (3.6 g/l) than in controls (3.1 g/l), with p < 0.001. Genotype was significantly associated with (adjusted) plasma fibrinogen level in controls (p = 0.003). This effect was confined to the smokers (n = 50) where mean fibrinogen level was significantly (p = 0.001) higher in G/A-455 and A/A-455 individuals (3.5 g/l) compared with G/G-455 homozygotes (2.9 g/l). There was a significant interaction between smoking status and genotype in determining plasma fibrinogen levels in the controls. These data provide independent confirmation of the association between beta-fibrinogen G/A-455 genotype and plasma fibrinogen levels previously observed in healthy men from the UK.

Exogenous rh-urokinase modifies inflammation and Pseudomonas aeruginosa infection in a rat chronic pulmonary infection model

The effect of recombinant human urokinase (rh-UK) in a rat model of chronic Pseudomonas aeruginosa pulmonary infection was studied. Efficacy was assessed by lung histology and quantitative bacteriology. Male Sprague-Dawley rats received 1 x 10(4) or 1 x 10(5) P. aeruginosa encapsulated in agar beads via the intratracheal route on day 1. Intratracheal administration of up to 12,500 units of rh-UK on day 21 led to a dose-dependent disappearance of viable organisms from the lungs by day 24 in rats receiving 10(4) organisms. In slightly longer term infections (30 days), rh-UK was still effective in facilitating the disappearance of the organisms from the lungs of most of the treated animals. rh-UK was effective in eliminating organisms when animals were infected with 10(4), but not 10(5) bacteria. In vitro analysis revealed that rh-UK was not directly toxic for the organisms. Histologically, lungs from short-term infected control animals exhibited acute inflammation, inflammatory cell infiltrates, and fibrin deposition. Histology of lungs from UK-treated, short-term infected rats revealed decreased airway inflammation and cellular infiltration compared with infected controls. Lungs from infected animals treated with 12,500 units of rh-UK were histologically indistinguishable from the lungs of uninfected control animals, except for the foreign body reaction. These results indicate that exogenous rh-UK may be efficacious in the treatment of pulmonary inflammation accompanying exposure to Gram-negative bacteria such as P. aeruginosa.

Use of jacalin as a solid phase in ABO reverse grouping

A major problem of using red cells as the solid phase in assay systems is the difficulty to bind them strongly to appropriate surfaces. We report here on a number of lectins of different specificities which were examined for their ability to bind red cells to polystyrene 96-well microtitre plates. The use of the Thomsen-Friedenreich antigen-specific lectins, jacalin, mushroom and Maclura pomifera agglutinin proved the most useful for ABO reverse grouping. Jacalin-coated plates were also compared with plates coated with poly-L-lysine and bovine serum albumin/glutaraldehyde for the binding of erythrocyte membranes and were found to be superior. We also describe the colorimetric detection of the solid phase red cell antibody reaction by using an indicator erythrocyte and peroxidase chromogenic substrate.

The two allele sequences of a common polymorphism in the promoter of the plasminogen activator inhibitor-1 (PAI-1) gene respond differently to interleukin-1 in HepG2 cells

We have detected a common (allele frequency 0.53/0.47) single base pair insertion/deletion polymorphism 675 base pairs upstream from the start of transcription of the plasminogen activator inhibitor-1 (PAI-1) gene, using the chemical cleavage mismatch analysis. "Band shift assays" suggest that the allele with the single base pair insertion contains an additional protein binding site which is not present in the del allele. Competition experiments confirmed that the binding was specific to the sequence of the ins allele and suggest that proteins bound to this site may be NF-kB-like proteins. Analysis of chloramphenicol acetyltransferase (CAT) mRNA produced by constructs containing the PAI-1 promoter (-805 to +83) showed that the deletion allele produced six times more mRNA than the insertion allele in response to interleukin-1 (p < 0.001). In a sample of 107 young patients with previous myocardial infarction and 95 healthy population-based subjects, the del allele was associated with increased PAI-1 levels, 21% higher than the sample mean in the del homozygotes (p < 0.05). This study also suggested that individuals homozygous for the del allele may have an altered response to the acute phase stimulus. Taken together these results suggest that the insertion/deletion polymorphism in the PAI-1 promoter is of functional importance in regulating the expression of the PAI-1 gene.

Natural antibodies to avidin in human serum

Human serum was found to contain natural antibodies to the egg-white glycoprotein avidin. Of 270 samples tested, all contained antibodies to different extents, mainly of the IgG and IgM classes. Anti-avidin antibodies could be isolated by affinity chromatography.

Decentralization of the superior cervical ganglia and the immediate hypersensitivity response

Bilateral decentralization of the superior cervical ganglia protects against pulmonary inflammation when measured 8 hr after induction of anaphylaxis in rats sensitized to the nematode, Nippostrongylus brasiliensis. Since anaphylactic shock produces immediate perturbations to the cardiovascular and respiratory systems, we examined whether bilateral decentralization of the superior cervical ganglia modified the responses of these two systems during the first 4 hr of the anaphylactic response. With the exception of the bronchioles, decentralization did not protect against anaphylaxis-associated increases in extravasation of albumin, and the small changes in respiratory function induced by anaphylaxis were unaffected by the denervation. Decentralization did not alter anaphylaxis-induced reductions in blood flow to the gastrointestinal tract; however, blood flow to the kidneys and spleen of decentralized rats was restored more rapidly to normal values. These results suggest that the protective effect of decentralization on the late phase pulmonary inflammation of anaphylaxis is unrelated to early changes in respiratory mechanics, although the protection may be facilitated by the more rapid re-establishment of normal cardiovascular homeostasis.

Genetic and environmental determinants of factor VII coagulant activity in ethnic groups at differing risk of coronary heart disease

It has been shown previously that individuals possessing the Gln353 allele of factor VII have significantly lower factor VIIc levels. In this population based study of Europeans, Afro-Caribbeans and Gujarati Indians, the Gln353 allele was associated with lower factor VIIc in all groups, carriers having factor VIIc levels 20-25% below the group mean. Although the Afro-Caribbeans had the lowest factor VIIc levels, the frequency of the Gln353 allele was not different from the European sample. However, in the Gujaratis, the frequency of the Gln353 allele was significantly higher than in the Europeans (0.25 compared to 0.09, P less than 0.001). Factor VIIc is known to be positively correlated with plasma triglyceride levels, although the Gujaratis, having the highest mean triglyceride levels, did not have the highest mean factor VIIc levels. On examination of the relationship between triglycerides and factor VIIc in the Gujaratis there was a correlation (r = 0.23, P = 0.13) in individuals homozygous for the factor VII Arg353 allele, but no correlation (r = 0.001, P = 0.5) among Gln353 carriers. This striking difference suggests that the effect of triglycerides on factor VIIc is genotype specific and thus provides an example of gene-environment interaction. The high frequency of the Gln353 allele, with its associated lack of relationship between triglyceride and factor VIIc levels, may explain the lower than expected factor VIIc levels in the Gujaratis.

Morphologic aspects of pericardial heart disease: Part II

Pericardial heart disease is a common entity at necropsy. Frequently, focal areas of fibrin deposits or parietal-visceral pericardial adhesion are observed at necropsy without previous clinical evidence of pericardial dysfunction. Some of these instances are related to clinically silent acute or healed myocardial infarction but the vast majority of cases are incidental (idiopathic) findings. The purpose of this review is to summarize various morphologic responses of the pericardium and to provide an etiologic framework for these responses. Part II will review specific morphologic responses of pericardial layers to selected diseases.

Allele specific amplification by tetra-primer PCR

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Morphologic aspects of pericardial heart disease: Part I

Pericardial heart disease is a common entity at necropsy. Frequently, focal areas of fibrin deposits or parietal-visceral pericardial adhesion are observed at necropsy without previous clinical evidence of pericardial dysfunction. Some of these instances are related to clinically silent acute or healed myocardial infarction, but the vast majority of cases are incidental (idiopathic) findings. The purpose of this review is to summarize various morphologic responses of the pericardium and to provide an etiologic framework for these responses. Part I will review general morphologic responses of pericardial layers.

Surface properties of rat pulmonary surfactant studied with the captive bubble method: adsorption, hysteresis, stability

Surface tension-area relations from pulmonary surfactant were obtained with a new apparatus that contains a leak free captive bubble of controllable size. Rat pulmonary surfactant was studied at phospholipid concentrations of 50, 200 and 400 micrograms/ml. At the highest concentration, adsorption was rapid, reaching surface tensions below 30 mN/m within 1 s, while at the lowest concentration, approximately 3 min were required. Upon a first quasi static or dynamic compression, stable surface tensions below 1 mN/m could be obtained by a film area reduction of approximately 50%. After three to four cycles the surface tension-area relations became stationary, and the tension fell from 25-30 to approximately 1 mN/m for a film area reduction of less than 20%. Hysteresis became negligible, provided the films were not collapsed by further area reduction. Under these conditions, the films could be cycled for more than 20 min without any noticeable loss in surface activity. After only three to four consecutive cycles, surfactant films exhibited the low surface tensions, collapse rates and compressibilities characteristic of alveolar surfaces in situ. Remarkably, surface tension and area are interrelated in the captive bubble which may promote low and stable surface tensions. If the surface tension of the captive bubble suddenly increases ('click') because of mechanical vibration or unstable surfactant, the bubble shape changes from flat to more spherical. The associated isovolumetric decrease in surface area prevents the surface tension from rising as much as it would have in a constant-area situation. This feedback mechanism may also have a favorable effect in stabilizing alveolar surface tension at low lung volumes.

Outbreak of hypersensitivity pneumonitis among mushroom farm workers

Between April 1982 and August 1985, seven cases of mushroom worker's lung (MWL), a form of hypersensitivity pneumonitis, were diagnosed among workers at one mushroom farm in Florida. The cases suffered from episodic shortness of breath, cough, fever and chills, myalgia, malaise, and difficulty breathing. Pulmonary function testing revealed restrictive ventilatory impairment and reduced diffusing capacity; chest radiographs exhibited diffuse interstitial pulmonary infiltrates. The seven cases occurred among workers from different farm operations, suggesting that workers throughout the farm were exposed to the disease causing agent(s). Six of the affected workers left employment at the farm in order to remain free of symptoms. The other affected worker was able to continue working at the farm, but only by remaining in a maintenance shop which was physically separated from the rest of the farm facilities. An industrial hygiene survey demonstrated that farm workers from every work area were exposed to organic dust constituents suspected of causing MWL, but no specific antigens were identified as the cause of the cases. Of the remaining workers who participated in a cross-sectional respiratory morbidity survey at the farm, approximately 20% of the more heavily exposed workers reported occasionally experiencing symptoms consistent with MWL. Approximately 10% of the workers had below normal spirometry test results, but interpretation was hampered by the diverse racial makeup of the population and lack of an adequate comparison group. No abnormalities consistent with either acute or chronic MWL were seen on the chest radiographs. Serologic tests demonstrated that almost all workers had been exposed to antigens capable of causing MWL, but the results were not associated with health status. At the time of the cross-sectional survey, no workers were found to be suffering acute respiratory problems consistent with MWL.

Cytokine production by cholesterol-loaded human peripheral monocyte-macrophages: the effect on fibrinogen mRNA levels in a hepatoma cell-line (HepG2)

Conditioned medium from human monocyte-macrophages incubated under various conditions was tested for its ability to stimulate fibrinogen mRNA levels in the hepatoma cell line HepG2. Recombinant human interleukin-6 (IL-6) stimulated fibrinogen mRNA levels 4.4-fold over control levels; this response was blocked by an anti-IL-6 antibody. Conditioned medium from 3-day-cultured monocyte-macrophages produced a slight stimulation of fibrinogen synthesis in HepG2 cells which was enhanced when the monocyte-macrophages had been treated with lipopolysaccharide (LPS). This stimulation was blocked by the anti IL-6 antibody. The cytokines, interleukin-1 (IL-1) and tumour necrosis factor (TNF) were also detected in the conditioned medium from the 3-day-cultured monocyte-macrophages. Monocyte-macrophages were cultured for 17 days and then incubated with acetylated low density lipoprotein (AcLDL) for 48 h. Such cells were 'foamy' in appearance and showed a 4-fold increase in apoE mRNA and a 10 to 50-fold increase in apoE secretion. This increase in apoE production was suppressed by almost a third when cells were coincubated with AcLDL and LPS. Conditioned medium from these 17-day-cultured AcLDL-treated human monocyte-macrophages did not stimulate fibrinogen mRNA synthesis in HepG2 cells, nor did the conditioned medium contain detectable levels of cytokines. These results suggest that cytokine production from foam cells in the atherosclerotic lesion is unlikely to be a major contributing factor in determining the elevated fibrinogen levels seen in the plasma of patients with IHD.

Catheter balloon valvuloplasty of stenotic aortic valves. Part I: Anatomic basis and mechanisms of balloon dilation

Catheter balloon valvuloplasty of stenotic aortic valves has met with generally poor short- and long-term clinical results. Part of this problem resides with the lack of recognition of various etiologies of aortic stenosis. Part I of this review discusses the various etiologies of aortic stenosis and provides an anatomic basis for successful valve dilation. Results of an in vitro study indicate stenotic aortic valves are dilated by various mechanisms (cracking, stretching) based in part upon the etiology of the aortic valve stenosis.

A common genetic polymorphism associated with lower coagulation factor VII levels in healthy individuals

We have identified a genetic polymorphism of factor VII that is strongly associated with plasma factor VII coagulant activity (factor VIIc) in healthy individuals from the United Kingdom. This polymorphism was detected after Msp I digestion of polymerase chain reaction-amplified genomic DNA. In a sample of 284 men, the frequency of the M2 allele (loss of cutting site) is 0.1, and individuals with the M1M2 genotype have factor VIIc levels 22% below the sample mean (p less than 0.0001). Msp I genotype was found to be the strongest predictor of factor VIIc, accounting for 20.2% of the variance, with cholesterol accounting for an additional 3.5%. The base change that gives rise to the Msp I polymorphism is a G-to-A substitution in the codon for amino acid 353, leading to replacement of arginine (Arg) with glutamine (Gln) in the protein product of the M2 allele (designated Gln 353). Three individuals homozygous for the M2 allele have both low factor VIIc and low factor VII protein concentrations. The conformation of the Gln 353 molecule may be different from that of the Arg 353 protein, affecting its intracellular processing, secretion, turnover in plasma, or activity. In view of its association with lower factor VIIc levels, possession of the M2 allele may confer protection against thrombosis and myocardial infarction.

Pathology of pulmonary parasitic migration: morphological and bronchoalveolar cellular responses following Nippostrongylus brasiliensis infection in rats

Nippostrongylus brasiliensis has an obligatory migratory phase through the lungs during its development in rats. This migration is associated with marked tissue damage and pronounced cellular reaction. Given that cells from the lower respiratory tract, especially alveolar macrophages, can adhere to and kill larvae of N. brasiliensis in vitro, we studied the time course of morphological changes associated with parasitic migration. Compared to a primary infection, a secondary infection resulted in significant changes in the pulmonary tissue characterized by an early acute inflammation leading to granulomatous reaction in the parenchyma and a leucocytosis in the bronchoalveolar lavage fluids with an anamnestic increase in absolute numbers of neutrophils, alveolar macrophages, eosinophils, and lymphocytes. Scanning electron microscopy showed that inflammatory cells, especially alveolar macrophages, granulocytes, lymphocytes, erythrocytes, and platelets, adhered to the larvae following secondary infection and this adhesion was associated with disruption of cuticular surface in some larvae. Secondary infection also resulted in retention of larvae in granulomatous lesions in the lungs even up to 21 days postinfection. There was mast cell and type II pneumocyte hyperplasia and these cells appeared to be activated. Thus, the histopathological changes in lungs correlated with the bronchoalveolar cellular responses and further document the inflammatory and immunological reactions during the migration of N. brasiliensis larvae.

Marked antiinflammatory effects of decentralization of the superior cervical ganglia

Intravenous challenge with parasite antigens in Nippostrongylus brasiliensis-sensitized rats resulted in anaphylactic shock and, in some animals, death. Surviving animals showed significant drop in mean arterial blood pressure, cardiac output, and blood flow to the trachea, bronchioles, and mesentery. After anaphylaxis, changes in the cellular and protein composition in bronchoalveolar lavage fluids (BALF) were assessed. 8 h after antigen challenge, there was significant influx of inflammatory cells and an increase in the levels of histamine and serum-derived immunoglobulins (IgG and IgM) in BALF. Chemotactic activity for neutrophils was also present in BALF. Once we established this anaphylaxis-induced model of pulmonary inflammation, we sought to determine whether or not the superior cervical ganglia (SCG) modulate this inflammation. We performed bilateral superior cervical ganglionectomy or decentralization of the SCG. Our results show that decentralization significantly reduced mortality (by 68%) after anaphylaxis. Furthermore, the increases in levels of serum-derived proteins, histamine, and influx of cells (especially neutrophils) observed in BALF after anaphylaxis were attenuated by both decentralization and ganglionectomy. By contrast, hemodynamic parameters in the respiratory tract and the presence of neutrophil chemotactic activity in BALF were not influenced by decentralization. Thus, the severity of pulmonary inflammation initiated by systemic anaphylaxis is depressed by bilateral ganglionectomy or decentralization of SCG.

Surfactant displaces particles toward the epithelium in airways and alveoli

This study was designed to investigate the early stages of particle deposition on airway and alveolar surfaces. To do this we used morphometric studies of aerosol deposition, in situ measurements of surface tension, and in vitro assays of particle displacement and mathematical modelling. We observed that latex particles, equal or less than 6 microns in diameter deposited in hamster lungs were submerged in the subphase of the alveolar lining layer and became completely coated with an osmiophilic film. Similar results were obtained for particles deposited in the conductive airways which were also covered with a surface active film, having a surface tension of 32 +/- 2 dyn.cm-1. In vitro experiments showed that pulmonary surfactant promotes the displacement of particles from air to the aqueous phase and that the extent of particle immersion depends on the surface tension of the surface active film. The lower the surface tension the greater is the immersion of the particles into the aqueous subphase. Mathematical analysis of the forces acting on a particle deposited on an air-fluid interface show that for small particles (less than 100 microns) the surface tension force is several orders of magnitude greater than forces related to gravity. Thus, even at the relatively high surface tension obtained in the airways (32 +/- 2 dyn.cm-1) particles will still be displaced into the aqueous subphase. Particles in peripheral airways and alveoli likely are below the surfactant film and submerged in the subphase. This may promote clearance by macrophages. In addition, particle displacement into the subphase is likely to increase the contact between the epithelial cell and particle. Toxic or allergenic particles would be available to interact with epithelial cells and this may be important in the pathophysiology of airway disease.

Capsaicin pretreatment modifies hydrogen sulphide-induced pulmonary injury in rats

One of the major target organs of hydrogen sulphide gas is the lung. Exfoliation of upper respiratory epithelia and pulmonary edema are prominent effects. Various neuropeptides contained in afferent C-fibres are intimately associated with the epithelia of the conducting airways and are liberated upon exposure to noxious gases. We sought to determine their role in the pathogenesis of hydrogen-sulphide-induced pulmonary injury by pretreating rats with the neurotoxin, capsaicin, which is known to ablate a subpopulation of vagal afferent C-fibres. Groups of capsaicin and saline (control) pretreated Fischer 344 rats were exposed to an edemogenic concentration of hydrogen sulphide (525-559 mg/m3) for 4 hr. Mortality was significantly greater (p less than 0.01) in the capsaicin treated rats (12/12) compared to the control animals (2/12). Pulmonary injury was also more severe in the capsaicin pretreated animals as assessed by lung water content, histological grade of pulmonary edema and protein in the broncho-alveolar fluid. Animals depleted of substance P exhibited a significantly greater (p less than 0.01) degree of bronchial epithelial cell exfoliation and ulceration following exposure to hydrogen sulphide. These experiments indicate that capsaicin sensitive sensory nerves may play a major role in pulmonary defense against the effects of inhaled toxic gases such as hydrogen sulphide.

Studies on the cellular mechanisms of action of positive and negative inotropic agents

We have reviewed the mechanism by which drugs that elevate cyclic AMP level modify myocardial contractility. We have presented preliminary evidence about the mechanism by which muscarinic agonists antagonize the effects of these drugs. Finally, we suggest that the protein phosphorylation experiments, particularly if done in dispersed myocytes, could be an efficient and cost-effective method of screening drugs which may act by elevating intracellular levels of cyclic AMP.

Reversible forskolin-induced impairment of sucrase-isomaltase mRNA levels, biosynthesis, and transport to the brush border membrane in Caco-2 cells

Hybridization analysis of mRNA with a cDNA probe for human sucrase-isomaltase, pulse-chase experiments with L-[35S]-methionine followed by SDS-PAGE, and immunofluorescence detection of sucrase-isomaltase were used to analyze the level(s) at which forskolin interferes with the expression of the enzyme in Caco-2 cells in culture. Three effects are observed in Caco-2 cells treated with forskolin: 1) a marked decrease in the level of sucrase-isomaltase mRNA, 2) a marked decrease in the biosynthesis of the enzyme without any alteration of its stability, and 3) an almost total inhibition of its transport to the brush border membrane. All three effects are reversible when the drug is removed from the culture medium, though this reversibility is asynchronous: transport to the brush border membrane resumes after 24 h, sucrase-isomaltase mRNA levels are back to the normal after 5 days, whereas the biosynthesis of the enzyme, although increasing progressively, remains lower than in control cells, even 10 days after removal of the drug. The possibility that some effects are directly dependent on cAMP and others a consequence of changes in glucose metabolism is discussed.

Adaptation of the Nelson-Somogyi reducing-sugar assay to a microassay using microtiter plates

The Nelson-Somogyi assay for reducing sugars was adapted to microtiter plates. The primary advantages of this modified assay are (i) smaller sample and reagent volumes, (ii) elimination of boiling and filtration steps, (iii) automated measurement with a dual-wavelength scanning TLC densitometer, (iv) increased range and reproducibility, and (v) automated colorimetric readings by reflectance rather than absorbance.

Apolipoprotein (apo) E genotypes by polymerase chain reaction and allele-specific oligonucleotide probes: no detectable linkage disequilibrium between apo E and apo CII

Allelic sequence variation in the apolipoprotein (apo) E gene has been analysed by means of synthetic oligonucleotide probes that detect single base pair substitutions in the codons for amino acid positions 112 and 158, substitutions that are responsible for the common isoforms. Use of the polymerase chain reaction procedure to amplify a sequence of 330 base pairs of the human apo E gene has permitted the development of a robust method for apo E genotyping. This technique has been used to determine the apo E genotype in 95 individuals in whom the genotype for an apo CII TaqI restriction fragment length polymorphism has also been determined. No strong linkage disequilibrium between the two gene loci was detected. This suggests that the metabolic effects of variation in the apo E and apo CII genes, as detected by the polymorphisms used here, would operate in a statistically independent manner.

Control of plasma fibrinogen levels

It is clear that the control of plasma fibrinogen levels is complex, involving not only many environmental factors such as alcohol intake, smoking habit, age, obesity and the acute phase response, but also genetic factors as shown by the association of the Bcl I RFLP of the beta-fibrinogen gene with plasma fibrinogen levels. The advent of recombinant DNA technology has made the dissection of the different factors controlling plasma fibrinogen levels a valid proposition, and great progress is already being made. The goals of this research are twofold. First, it may be possible to develop DNA tests to identify individuals who, on the basis of their genotype, are at high risk of ischaemic heart disease. Once identified, the subsequent risk of these individuals can be reduced by modifying life-style or by drug therapy to reduce other known risk factors such as cholesterol levels. Second, once the mechanisms controlling fibrinogen concentration are better understood at the molecular level, it may be possible to develop directed therapeutic strategies that will reduce fibrinogen synthesis in a specific manner, an approach that is not possible at present. In the future, such pharmacological agents may have as wide an impact on reducing ischaemic heart disease as cholesterol-lowering drugs do today.

Resectable bronchogenic carcinoma presenting with hypercalcemia: tumor-associated granulomatous reaction and probable production of 1,25-dihydroxyvitamin D

A patient with hypercalcemia, increased levels of 1,25-dihydroxyvitamin D, and a resectable squamous cell bronchogenic carcinoma surrounded by numerous non-caseating epithelioid granulomas, achieved normocalcemia, decreased levels of 1,25-dihydroxyvitamin D, and no evidence of tumor recurrence at 30 months following complete resection of his tumor. We suggest that an excess production of 1,25-dihydroxyvitamin D, through the granulomatous reaction around the tumor, was the mechanism of hypercalcemia. To our knowledge, no such mechanism of hypercalcemia has been previously reported with bronchogenic carcinoma. Furthermore, a review of the literature reveals that in cases of bronchogenic carcinoma, hypercalcemia is almost always associated with large and unresectable tumors, with a median survival after the discovery of hypercalcemia of only one month. This case, then, is unique because it describes an unusual mechanism of hypercalcemia with bronchogenic carcinoma and it emphasizes the rare occurrence of the potentially curable patient presenting with bronchogenic carcinoma complicated by hypercalcemia.

Acquired immunity to Trichophyton mentagrophytes in thymus-grafted or peritoneal exudate cell-injected nude rats

Congenitally athymic "nude" (RNU/RNU) rats were grafted with syngeneic neonatal thymus glands and 30 days later cutaneously inoculated with Trichophyton mentagrophytes. Nude rats and thymus-grafted nude rats were susceptible to infection with T. mentagrophytes but only thymus-grafted nude rats cleared the dermatophytosis. Clearance of the fungal infection took twice as long (approximately 60 days) in thymus-grafted nude rats when compared with heterozygous euthymic (+/RNU) controls (approximately 35 days). Following clearance of the primary dermatophytosis, peritoneal exudate cells (PEC) were adoptively transferred from either thymus-grafted or heterozygous rats to nude rats. Eight of 12 PEC-recipient nude rats acquired the capacity to resolve T. mentagrophytes-induced dermatophytosis (mean clearance time was approximately 40 days). All heterozygous (+/RNU) rats, thymus-grafted nude rats (4/4), and 8 of 12 PEC-recipient nude rats, which had cleared a primary dermatophytosis also expressed delayed-type hypersensitivity and elevated serum antibody titers to trichophytin antigen. These results demonstrate that immunity to T. mentagrophytes can be acquired in congenitally athymic nude rats following thymus grafting or injection of PEC from syngeneic +/RNU rats; however, injection of PEC from trichophytin-sensitized +/RNU donor rats to nude recipient rats did not result in transfer of specific adoptive immunity to T. mentagrophytes. Interestingly, PEC transfer from non-sensitized +/RNU rats was comparable to thymus grafting in effecting clearance of T. mentagrophytes dermatophytosis. These results suggest that acquired immunity to T. mentagrophytes in the rat is T cell-dependent, and that the absence of functional T lymphocytes and not an epithelial defect results in chronic dermatophytosis in the nude rat.

Isolation of a cDNA probe for a human jejunal brush-border hydrolase, sucrase-isomaltase, and assignment of the gene locus to chromosome 3

We report the nucleotide sequence and derived amino acid sequence of a cDNA clone encoding most of the N-terminal, isomaltase region of human sucrase-isomaltase (SI). A plasmid containing this cDNA, pS12, identifies a 6-kb mRNA found in human jejunum and the human colon carcinoma cell line Caco-2. This human SI cDNA shows extensive overall homology with recently published rabbit SI cDNA. Using pS12 to probe DNA from a panel of somatic cell hybrids, we have assigned the gene encoding human SI to chromosome 3.

A procedure for isolation and partial purification of guinea pig lung mast cells

Pulmonary mast cells were obtained from guinea pig lung using a combination of enzymatic digestion of tissue, centrifugal elutriation, and density gradient centrifugation on Percoll. In the initial procedure, lung tissue was enzymatically digested with collagenase and elastase in four 30 min incubations. Typically, monodispersed cell suspensions contained 4% mast cells. Further purification of these lung mast cells using elutriation and Percoll gradients consistently yielded mast cells of 40-78% (mean 51%) purity. These cells were morphologically intact, viable and found to be functional as determined by histamine release evoked by antigen and anti-guinea pig IgG1 antibody.

Preparation of a monoclonal antibody against human lactase

A simple procedure for screening for anti-enzyme monoclonal antibodies is described. The properties of our first antibody identified this way, directed against human lactase, are reported.

The thymus dependency of acquired resistance to Trichophyton mentagrophytes dermatophytosis in rats

Congenitally athymic "nude" (RNU/RNU) rats and euthymic (+/RNU) rats were cutaneously inoculated with Trichophyton mentagrophytes. Dermatophytosis, as evidenced by erythema and scaling, was observed in both athymic and euthymic rats by day 7 postinfection. Macroscopic lesions in +/RNU rats became intensely erythematous (climax days 10-14), were limited in spread and alopecia (days 16-20), and healed with hair regrowth by day 35. In nude rats, however, erythema peaked early (days 8-10) and a persistent, mild erythema and scaling spread over the animals' backs. Viable T. mentagrophytes was cultured from the skin of all infected nude rats for the duration of each experiment (90 days), while +/RNU rats became culture-negative by day 35. Following clearance of primary lesions, +/RNU rats manifest a delayed-type hypersensitivity skin test response to soluble trichophytin and an accelerated cutaneous inflammation and enhanced resistance to reinfection. Although T. mentagrophytes primarily invaded the keratinized layers of the epidermis in both nude and +/RNU rats, hyphae and arthrospores were also observed within the nucleated layers of the internal root sheath of hair follicles. Our observations are consistent with the hypothesis that thymus-dependent cell-mediated immunity is required to limit cutaneous spread and terminate cutaneous T. mentagrophytes infection. This acquired immunity against T. mentagrophytes in +/RNU rats was characterized histologically by: (1) an intense inflammatory migration of lymphocytes, monocytes, and macrophages into the epidermis, dermis, and follicular epithelium; (2) hyperplasia of the epidermis and follicular epithelium; and (3) elimination of arthrospores and hyphae from T. mentagrophytes-infected skin.