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Biomedical subjects

D A Schwartz

Publications and source records attributed to D A Schwartz.

At least 19 recordsLinked to original sources
PubMed1997

CpG motifs in bacterial DNA cause inflammation in the lower respiratory tract.

Since unmethylated CpG motifs are more frequent in DNA from bacteria than vertebrates, and the unmethylated CpG motif has recently been reported to have stimulatory effects on lymphocytes, we speculated that bacterial DNA may induce inflammation in the lower respiratory tract through its content of unmethylated CpG motifs. To determine the role of bacterial DNA in lower airway inflammation, we intratracheally instilled prokaryotic and eukaryotic DNA in C3H/HeBFEJ mice and performed whole lung lavage 4 h after the exposure. Heat denatured, single stranded Escherichia coli genomic DNA (0.06 ng endotoxin/microg DNA) was compared to heat denatured, single stranded calf thymus DNA (0.007 endotoxin/microg DNA). 10 microg of bacterial DNA, in comparison to 10 microg of calf thymus DNA, resulted in a fourfold increase in the concentration of cells (P = 0.0002), a fivefold increase in the concentration of neutrophils (P = 0.0002), a 50-fold increase in the concentration of TNF-alpha (P = 0.001), and a fourfold increase in the concentration of both IL-6 (P = 0.0003) and macrophage inflammatory protein-2 (P = 0.0001) in the lavage fluid. Importantly, instillation of 0.60 ng of E. coli LPS resulted in a negligible inflammatory response. To test whether the stimulatory effects of bacterial DNA are due to its unmethylated CpG dinucleotides, we methylated the bacterial DNA and also prepared 20 base pair oligonucleotides with and without CpG motifs. In comparison to instillation of untreated bacterial DNA, methylation of the bacterial DNA resulted in a significant reduction in the concentration of cells and cytokines in the lower respiratory tract. Moreover, oligonucleotides containing embedded unmethylated CpG motifs resulted in inflammation in the lower respiratory tract that was indistinguishable from that observed with untreated bacterial DNA. In contrast, oligonucleotides without the embedded CpG motifs or with embedded but methylated CpG motifs resulted in significantly less inflammation in the lower respiratory tract. The possible relevance of these data to human disease was shown by extracting and analyzing DNA in sputum from patients with cystic fibrosis (CF). Approximately 0.1 to 1% of this sputum DNA was bacterial. Intratracheal instillation of highly purified CF sputum DNA caused acute inflammation similar to that induced by bacterial DNA. These findings suggest that bacterial DNA, and unmethylated CpG motifs in particular, may play an important pathogenic role in inflammatory lung disease.

Animals↗
PubMed1997

The kinetics of grain dust-induced inflammation of the lower respiratory tract.

To characterize the kinetics of grain dust-induced airflow obstruction and inflammation in the lower respiratory tract, we performed serial spirometry and bronchoalveolar lavage (BAL) in human subjects and whole-lung lavage in mice following a single inhalation exposure to comparable dosages of corn dust extract (CDE). Following inhalation of CDE, our human study subjects developed significant airflow obstruction 10 min postexposure which persisted for 48 h. Human subjects and mice had similar acute and persistent changes in lavage cellularity after exposure to CDE. A profound increase in the concentration of lavage neutrophils was present in the initial postexposure lavage in both human subjects and mice. This increase persisted for 96 h in human subjects and 48 h in mice. Small but significant increases in lavage macrophage concentration were present 48 h postexposure in human subjects and at 96 h postexposure in mice. Inhalation of CDE resulted in a significant increase in the concentration of proinflammatory cytokines tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) in the lavage fluid of both human subjects and mice. Similarly, significant increases in lavage concentrations of IL-8 in humans and macrophage inflammatory protein-2 (MIP-2) in mice occurred after inhalation of CDE. The lavage concentration of all measured proinflammatory cytokines returned to baseline levels by 168 h in humans and 96 h in mice. These findings suggest that a single inhalation challenge of CDE results in airflow obstruction and lower respiratory tract inflammation that may last for several days. These physiologic and inflammatory responses appear to be self-limited with no evidence of persistent injury 1 wk after the inhalation challenge. Moreover, the inflammatory response in the lower respiratory tract after inhalation of grain dust is similar in human subjects and mice, suggesting that the mouse may be an appropriate model for further investigation of grain dust-induced inflammation.

Adult↗
PubMed1997

Quantification of idiopathic pulmonary fibrosis using computed tomography and histology.

We used computed tomography (CT) and histologic analysis to quantify lung structure in idiopathic pulmonary fibrosis (IPF). CT scans were obtained from IPF and control patients and lung volumes were estimated from measurements of voxel size, and X-ray attenuation values of each voxel. Quantitative estimates of lung structure were obtained from biopsies obtained from diseased and normal CT regions using stereologic methods. CT density was used to calculate the proportion of tissue and air, and this value was used to correct the biopsy specimens to the level of inflation during the CT scan. The data show that IPF is associated with a reduction in airspace volume with no change in tissue volume or weight compared with control lungs. Lung surface area decreased two-thirds (p < 0.001) and mean parenchymal thickness increased tenfold (p < 0.001). An exudate of fluid and cells was present in the airspace of the diseased lung regions and the number of inflammatory cells, collagen, and proteoglycans was increased per 100 g of tissue in IPF. We conclude that IPF reorganized lung tissue content causing a loss of airspace and surface area without increasing the total lung tissue.

Aged↗
PubMed1997

Pentoxifylline does not alter the response to inhaled grain dust.

Pentoxifylline (PTX) has been shown to reduce sepsis-induced neutrophil sequestration in the lung and inhibit endotoxin-mediated release of tumor necrosis factor-alpha (TNF-alpha). Previously, we have shown that endotoxin appears to be the principal agent in grain dust causing airway inflammation and airflow obstruction following grain dust inhalation. To determine whether PTX affects the physiologic and inflammatory events following acute grain dust inhalation, 10 healthy, nonsmoking subjects with normal airway reactivity were treated with PTX or placebo (PL) followed by corn dust extract (CDE) inhalation (0.08 mL/kg), using a single-blinded, crossover design. Subjects received PTX (1,200 mg/d) or PL for 4 days prior to CDE inhalation and 400 mg PTX or PL on the exposure day. Both respiratory symptoms and declines in FEV1 and FVC occurred following CDE exposure in both groups, but there were no significant differences in the frequency of symptoms or percent declines from baseline in the FEV1 and FVC at any of the time points measured in the study. Elevations in peripheral blood leukocyte and neutrophil concentrations and BAL total cell, neutrophil, TNF-alpha, and interleukin-8 concentrations were measured 4 h following exposure to CDE in both the PTX- and PL-treated subjects, but no significant differences were found between treatment groups. These results suggest that pretreatment with PTX prior to inhalation of CDE, in the doses used in this study, does not alter the acute physiologic or inflammatory events following exposure to inhaled CDE.

Administration, Inhalation↗
PubMed1997

Tumor imaging with technetium-99m-labeled hydrazinonicotinamide-Fab' conjugates.

UNLABELLED: This study compares the in vivo properties of direct versus indirect 99mTc-labeling for two Fab' fragments from antibodies that recognize tumor-associated antigens. METHODS: Fab' fragments of two IgG2a monoclonal antibodies were either radiolabeled directly or via the linker bromoacetyl hydrazinonicotinamide hydrobromide (BAHNH) conjugated site specifically at protein thiols. A thiol assay was used to determine the number of thiols in the Fab' and to monitor their consumption during conjugation with BAHNH. Both preparations were labeled to > 95% incorporation of 99mTc, with the isotope tracking the single 50 kD absorbance peak seen on size-exclusion HPLC. The labeled preparations were tested in tumor-bearing and control mice, with dissections at 4 and 24 hr and gamma scintigraphy of the tumor-bearing mice. RESULTS: The major difference between the two labeled preparations for either antibody fragment was the greater accumulation of isotope in the tumor for the indirectly labeled preparations. This increase ranged from 1.5- and 2.7-fold at 4 hr to 2.6- and 3.2-fold at 24 hr for the two antibodies, respectively. Since blood clearance was similar for the two labeling methods, the higher tumor accumulation with the indirectly labeled fragments resulted in higher tumor to blood ratios. Tumors could be imaged with both antibodies with either type of labeling with greater clarity and sensitivity at the 24 hr time point. CONCLUSION: While both labeling methods resulted in tumor detection through imaging, the images obtained with the indirectly labeled antibody fragments were more easily visualized due to the combination of higher radioisotope accumulation in the tumor and similar blood clearances compared to the direct labeled fragment.

Animals↗
PubMed1997

Coinfection with Giardia lamblia and Enterocytozoon bieneusi in a patient with acquired immunodeficiency syndrome and chronic diarrhea.

Diarrhea is an important clinical problem in immunosuppressed patients with acquired immunodeficiency syndrome (AIDS). There are numerous classical as well as emerging enteric pathogens that can produce diarrhea; however, these agents can be missed when only one method, such as microbiological examination of stool, is used for diagnosis. The endoscopic biopsy is a sensitive method for diagnosis of many viral, fungal, and parasitic infections of the gastrointestinal tract. Although only one agent is often identified in mucosal biopsies from these immunosuppressed patients, coinfection with multiple microbial agents is being increasingly recognized. Giardia infection is not as prevalent as other pathogens in patients with AIDS, but it remains an important diarrheal agent that is potentially curable. However, there have been only rare reports of coinfections with giardiasis and other infectious agents. This report describes a patient with AIDS and chronic diarrhea who had repeated negative stool examinations for ova and parasites. Light and electron microscopic examination of subsequent endoscopically obtained small intestinal biopsies revealed coinfection with two parasites, Enterocytozoon bieneusi and Giardia lamblia. Following treatment with metronidazole for giardiasis, the diarrhea persisted, but was less severe. This report also describes the diagnostic features of Giardia and Enterocytozoon infections in biopsy tissues and emphasizes the importance of identifying enteric coinfections in patients with AIDS to ensure timely and specific modes of therapy.

AIDS-Related Opportunistic Infections↗
PubMed1997

Emerging and reemerging infections. Progress and challenges in the subspecialty of infectious disease pathology.

Emerging and reemerging infections are attracting greater attention from the public health and medical communities. Pathologists and other physicians are increasingly aware of the importance of the subspecialty of infectious disease pathology as a tool for diagnosis, surveillance, and research of emerging infections. In this communication, we describe the role that infectious disease pathologists have played during the last 2 years in broadening our understanding of selected emerging infections, including such examples as new variant Creutzfeldt-Jakob disease and bovine spongiform encephalopathy, leptospirosis, microsporidiosis, Ebola hemorrhagic fever, and cyclosporiasis. The significance of providing pathology services, especially the autopsy, to patients with potentially hazardous communicable diseases is discussed with the supposition that it is unethical to exclude or withhold health care from a patient based on his or her underlying disease or on risk factors for acquiring a disease. The increasing occurrence of infectious diseases imported into the United States and other nations, including human immunodeficiency virus-1 group O, dengue fever, tuberculosis, malaria, diphtheria and cholera in immigrants and travelers, and Ebola virus in nonhuman primates, emphasizes the necessity for pathologists of having competence with infectious disease pathology. It is critical that new generations of pathologists not only be trained in the subspecialty of infectious disease pathology, but that they also be willing participants in the diagnosis and investigation of infectious diseases. The lack of training programs for infectious disease pathologists, as well as the deficiency in infectious disease pathology support for ongoing and future epidemiologic investigations and research, has led to the broadening of pathology services and initiation of a dedicated section of Infectious Disease Pathology at one of the nation's premier public health institutions, the Centers for Disease Control and Prevention in Atlanta, Ga. Together with preexisting groups of medical and veterinary infectious disease pathologists at universities, the Armed Forces Institute of Pathology, the US Army Medical Research Institute of Infectious Diseases, and the National Institutes of Health, this new program will significantly strengthen the capability of the United States to respond to future challenges of emerging and reemerging infections, both in this country and abroad.

Animals↗
PubMed1997

Diagnosis of Enterocytozoon bieneusi (microsporidia) infections by polymerase chain reaction in stool samples using primers based on the region coding for small-subunit ribosomal RNA.

OBJECTIVE: Enterocytozoon bieneusi is the most prevalent microsporidian causing chronic diarrhea in patients with acquired immunodeficiency syndrome. The current methods used for routine diagnosis of infections caused by microsporidia are based on microscopic detection of the microorganism spores in stained smears. We evaluated the usefulness of the polymerase chain reaction (PCR) technique as a tool to diagnose Enterocytozoon bieneusi infections, using the species-specific diagnostic primer pair EBIEF1/EBIER1 on stool samples that were also analyzed by optical microscopy. DESIGN: To perform PCR in such samples, we developed a novel protocol to obtain DNA free of PCR inhibitors. This protocol was based on disruption of spores using glass beads and overnight digestion with proteinase K; final purification was accomplished with the RapidPrep Micro Genomic DNA isolation Kit for Cells and Tissues (Pharmacia Biotech Inc, Piscataway, NJ). We also evaluated this approach on aliquots of a sample fixed in formalin from 1 to 10 days. PATIENTS AND SAMPLES: We evaluated the PCR technique on 64 stool samples obtained from patients with acquired immunodeficiency syndrome who had persistent chronic diarrhea. Patients were from Spain, Brazil, Germany, and the United States. RESULTS: Using this approach, we could confirm the presence of E bieneusi in all 17 positive samples; no false-positive results were observed. We could also amplify E bieneusi DNA in 10 aliquots of one sample fixed up to 10 days in 10% formalin. CONCLUSION: We conclude that PCR technology is very suitable for species identification of microsporidia in stool samples and may have a potential application in prospective studies in formalin-fixed samples.

Animals↗
PubMed1997

A new and improved "quick-hot Gram-chromotrope" technique that differentially stains microsporidian spores in clinical samples, including paraffin-embedded tissue sections.

OBJECTIVE: This report describes a new and improved "quick-hot Gram-chromotrope" staining technique that detects microsporidian spores in clinical specimens, such as stool, urine, saliva, nasopharyngeal fluid, and bronchoalveolar lavage samples, as well as in formalin-fixed and paraffin-embedded tissue sections. DESIGN: In this procedure, the samples are stained in heated (50 degrees C to 55 degrees C) solutions of crystal violet and iodine used in Gram's stain, followed by a modified chromotrope solution (heated to 50 degrees C to 55 degrees C). The modified stain is composed of chromotrope 2R (1%), fast green (0.15%), and phosphotungstic acid (0.25%). RESULTS: With this stain and the new protocol, microsporidian spores are stained dark violet against a pale green background, and the total staining time is shortened to 5 minutes. CONCLUSIONS: This new technique is fast, reliable, and simple. It can be easily adapted for use in clinical laboratories.

Animals↗
PubMed1996

Synthesis and thermodynamics of oligonucleotides containing chirally pure R(P) methylphosphonate linkages.

Methylphosphonate (MP) oligodeoxynucleotides (MPOs) are metabolically stable analogs of conventional DNA containing a methyl group in place of one of the non-bonding phosphoryl oxygens. All 16 possible chiral R(P) MP dinucleotides were synthesized and derivatized for automated oligonucleotide synthesis. These dimer synthons can be used to prepare (i) all-MP linked oligonucleotides having defined R(P) chirality at every other position (R(P) chirally enriched MPOs) or (ii) alternating R(P) MP/phosphodiester backbone oligonucleotides, depending on the composition of the 3'-coupling group. Chirally pure dimer synthons were also prepared with 2'-O-methyl sugar modifications. Oligonucleotides prepared with these R(P) chiral methylphosphonate linkage synthons bind RNA with significantly higher affinity than racemic MPOs.

Chromatography, High Pressure Liquid↗
PubMed1996

Sequence requirements for secondary glucocorticoid inducibility of rat alpha 2u globulin genes.

The transcription of the rat alpha 2u globulin gene family is under complex hormonal control, involving the participation of glucocorticoids, estrogens, insulin, and growth hormone. The glucocorticoid induction of alpha 2u globulin is a secondary response; that is, ongoing protein synthesis is necessary for induction of alpha 2u globulin mRNA by the hormone. This secondary response is maintained when alpha 2u globulin genes are transfected into tissue culture cells which contain the glucocorticoid receptor. We have found that the glucocorticoid induction of alpha 2u globulin occurs only in permanent cell lines, in which the alpha 2u globulin genes are integrated into the host cell DNA; induction in transient transfections is minimal. Further, the DNA sequences required for alpha 2u globulin secondary response lie entirely in the 5' proximal promoter region; no intragenic sequence elements are required for, or participate in, the secondary response to glucocorticoids.

Alpha-Globulins↗
PubMed1996

Antisense oligonucleotide containing an internal, non-nucleotide-based linker promote site-specific cleavage of RNA.

We have designed and synthesized a series of novel antisense methylphosphonate oligonucleotide (MPO) cleaving agents that promote site-specific cleavage on a complementary RNA target. These MPOs contain a non- nucleotide-based linking moiety near the middle of the sequence in place of one of the nucleotide bases. The region surrounding the unpaired base on the RNA strand (i.e. the one directly opposite the non-nucleotide-linker) is sensitive to hydrolytic cleavage catalyzed by ethylenediamine hydrochloride. Furthermore, the regions of the RNA comprising hydrogen bonded domains are resistant to cleavage compared with single-stranded RNA alone. Several catalytic moieties capable of supporting acid/base hydrolysis were coupled to the non-nucleotide-based linker via simple aqueous coupling chemistries. When tethered to the MPO in this manner these moieties are shown to catalyze site-specific cleavage on the RNA target without any additional catalyst.

Base Sequence↗
PubMed1996

Ontogenic and glucocorticoid-accelerated expression of rat 14 kDa bile acid-binding protein.

BACKGROUND: A 14 kDa protein is a major rat ileal cytosolic bile acid-binding protein (14 kDa I-BABP). This report describes the normal and glucocorticoid-accelerated postnatal expression of 14 kDa I-BABP. METHODS. 14 kDa I-BABP and its mRNA were detected by antiserum and antisense cRNA probe, respectively, in ileum and ovary from 7-, 14-, 21-, 28-, and 35-day-old rats. RESULTS: A positive histochemical reaction with 14 kDa I-BABP antiserum was found in cytosol of ileal enterocytes and ovarian luteal cells at 21 and 35 days of age, respectively. Likewise, Northern blot analysis indicated that the cRNA probe hybridized to a single transcript of 500 bp in total cellular RNA prepared from the ileum of 21-day-old and ovary of 35-day-old rats. Corticosteroid treatment resulted in a histochemical reaction in ileum of 14-day-old animals as compared to the appearance of this reaction in 21-day-old control littermates. Similarly, Northern blot analysis detected the earlier appearance of mRNA levels in corticosteroid-treated animals (11 days vs. 17 days in control animals). CONCLUSIONS: 14 kDa I-BABP and its mRNA are normally expressed in rat ileum at 17 days of postnatal life. 14 kDa I-BABP is expressed considerably later in rat ovary. Corticosteroid treatment results in precocious expression of ileal 14 kDa I-BABP.

Age Factors↗
PubMed1996

Rheumatoid arthritis lung disease. Determinants of radiographic and physiologic abnormalities.

OBJECTIVE: To determine the prevalence and important clinical predictors of radiographic and physiologic abnormalities indicative of rheumatoid arthritis interstitial lung disease (RA-ILD). METHODS: An unselected cohort of patients with a confirmed diagnosis of RA and known lung disease were identified (n = 336) and evaluated for RA disease activity and severity. Outcomes included abnormalities determined by the pulmonary function tests of forced vital capacity (FVC) and diffusion capacity for carbon monoxide (DLco), and/or chest radiographic findings of interstitial infiltrates. We used multivariable statistical modeling to determine the independent significance of cigarette smoking and other RA-specific factors on the pulmonary abnormalities of interest. RESULTS: At least 1 of the 3 abnormal findings was identified by pulmonary tests in 32.4% of all patients. These abnormal findings included an FVC < 80% of predicted in 42 patients, a DLco < 80% of predicted in 64 patients, and evidence of radiographic interstitial infiltrates in 40 patients. After statistical adjustment for confounding factors, pack-years of cigarette smoking remained a significant predictor of low DLco (beta = -0.07, 95% confidence interval [95% CI] -0.09, -0.04), low FVC (beta = -0.003, 95% CI -0.006, -0.0004), and interstitial abnormalities on chest radiograph (odds ratio for > or = 25 pack-years = 3.76, 95% CI 1.59, 8.88). The Health Assessment Questionnaire (HAQ) Disability Index (DI) was also an important risk factor for the decline in both the DLco (beta = -1.15, 95% CI -2.00, -0.30) and FVC (beta = -0.23, 95% CI -0.32, -0.13). CONCLUSION: Although RA disease activity/severity (particularly as defined by the HAQ DI) was important, smoking was the most consistent independent predictor of radiographic and physiologic abnormalities suggestive of ILD in RA.

Adult↗