Lens-specific expression of a major histocompatibility complex class I molecule disrupts normal lens development and induces cataracts in transgenic mice.

PURPOSE: Lens epithelial tissue does not normally express major histocompatibility complex (MHC) class I molecules. In addition, the mechanism of self-tolerance to intraocular antigens is unknown. To study the effect of class I expression in the lens, transgenic mice were produced that express an allo-MHC class I molecule under the alpha A-crystallin proximal promoter. METHODS: p alpha Dd was generated by fusion of the H-2Dd structural gene to the alpha A-crystallin proximal promoter. Transgenic mice were produced, and founder lines were identified by Southern blot hybridization. Eyes from transgenic mice were cryostat sectioned and stained for Dd expression or fixed in paraformaldehyde and stained for histologic analysis. Lens RNA was isolated by acid phenol extraction, and transgene expression was analyzed by nuclease protection. RESULTS: The transgenic mice demonstrated dose-dependent, nonimmunologic lens defects consistent within a given line. In the highest expressing lines, ocular defects, including microphthalmia and cataract formation, were observed. Many adult mice from these lines demonstrated lens capsule rupture and a Dd-specific inflammatory response. Inflammation did not occur in mice with intact lens capsules. CONCLUSIONS: Overexpression of H-2Dd in the lens had serious nonimmunologic consequences on lens development and cataract formation. In addition, the high copy number mice revealed at least a partial loss of immunologic tolerance on lens capsule rupture. The lack of an inflammatory response in transgenic mice with intact lens capsules suggests that the physical barrier of the lens capsule is one mechanism of maintaining immune privilege.

Transgenic expression of IFN-gamma in the murine lens results in multiple ocular abnormalities and an early but self-limited inflammatory response.

The anterior chamber of the eye is known to be an immune privileged site, due to both local and systemic effects on the immune response. Injection of IFN-gamma into the anterior chamber (AC) overcomes the suppression of antigen-specific delayed hypersensitivity responses normally seen in the eye. Transgenic mice expressing increased IFN-gamma in the lens under the alpha A-crystallin promoter were produced to determine whether the proinflammatory effects of IFN-gamma would abolish immune privilege and promote loss of tolerance as has been seen in non-immune privileged tissues. Two alpha C/IFN-gamma transgenic lines are described which demonstrate multiple ocular and lenticular abnormalities some of which are developmental in origin and others that may be secondary to the inflammatory effects of IFN-gamma. A significant inflammatory cell infiltrate which is observed in the AC and vitreous from birth to 4 weeks of age, consists initially of macrophage and polymorphonuclear leukocytes and then CD4+ T lymphocytes. However, the infiltrate is essentially resolved by 6 weeks of age. Therefore, although lens-specific expression of IFN-gamma results in early loss of immune privilege, chronic uveitis does not occur probably due to the lack of continued IFN-gamma expression.

Prevalence of infective endocarditis in patients with systemic lupus erythematosus.

BACKGROUND: Compared with the general population, patients with systemic lupus erythematosus, or SLE, have an increased prevalence of functionally impaired cardiac valves due to the presence of Libman-Sacks lesions. These lesions may place patients with SLE at risk of developing infective endocarditis, or IE. METHODS: The authors performed a retrospective chart review to determine the association between SLE with valvulopathy and IE. They reviewed the records of 361 patients from two health care facilities who had the diagnostic code of SLE. RESULTS: Of the 275 records that met the 1982 revised American Rheumatism Association criteria for SLE, 51 (18.5 percent) were for patients who had a clinically detectable heart murmur that resulted in echocardiography being performed. Nine (3.3 percent) of the 275 patients had a clinically significant valvular abnormality, three (1.1 percent) had a potentially significant valvular abnormality, and one (0.4 percent) had a history of IE that was diagnosed two years before her diagnosis of SLE was made. CONCLUSIONS: The findings suggest that 18.5 percent of this cohort of patients with SLE had a clinically detectable heart murmur that would require further investigation to determine its significance. Furthermore, between 3.3 and 4.4 percent of the study population had cardiac valve abnormalities that potentially required antibiotic prophylaxis before certain dental procedures. However, the authors identified no cases that demonstrated an association between IE and diagnosed SLE. CLINICAL IMPLICATIONS: Dentists should query their patients with SLE about their cardiac status and consult with the patient's physician if the cardiac status is unknown. Patients with confirmed valvular abnormalities should receive antibiotic prophylaxis for designated bacteremia-producing dental procedures.

Catastrophic antiphospholipid antibody syndrome presenting with multiple thromboses and sites of avascular necrosis.

We describe the case of a 25-year-old woman who presented with the antiphospholipid antibody syndrome (APS) manifesting as hemolytic anemia, thrombocytopenia, renal insufficiency, thromboses in multiple sites including skin, spleen and nasal mucosa, and multiple sites of avascular necrosis of bone. Interestingly, she also had low grade disseminated intravascular coagulation, which has been suggested to be a mechanism for avascular necrosis. We suggest that the APS may be one cause of thrombosis in avascular necrosis.

Requirements for induction of the biodegradative threonine dehydratase in Escherichia coli.

Synthesis of the biodegradative L-threonine dehydratase in Escherichia coli, Crookes strain, was prevented by dissolved oxygen concentrations of 6 micrometer or greater. This effect was shown to be exerted solely on synthesis, rather than being the result of enzyme inactivation in vivo. In addition to an anaerobic environment, maximum enzyme synthesis was dependent upon the presence of a complete complement of amino acids, with omission of L-threonine, L-valine, or L-leucine producing the largest decreases in enzyme formation. L-Threonine, the most essential of the amino acid requirements, could be partially replaced by DL-allothreonine or alpha-ketobutyrate. Half-maximal stimulation of enzyme synthesis occurred with 0.4 mM threonine in the medium. The roles of anaerobiosis and amino acids are interpreted as being in accord with the concept that threonine dehydratase functions in anaerobic energy production under conditions of amino acid sufficiency.

Dorsal lumbotomy for surgery of the upper urinary tract.

Between July 1978 and December 1985, 100 patients underwent an operation on the kidneys and ureter through the dorsal lumbotomy approach. A total of 12 patients underwent dismembered pyeloplasty for ureteropelvic junction obstruction. Compared to patients who underwent an operation via the standard flank incision, these 12 patients had significantly shorter hospitalization and fewer doses of analgesics. The treatment demonstrated improved cost-effectiveness. Similar advantages were noted in the remaining patients in whom removal of calculi (78), open renal biopsy (5), simple nephrectomy (4) and removal of a foreign body in the ureter (1) were done through the dorsal lumbotomy approach. We appeal for a renaissance of the dorsal lumbotomy approach in urological teaching and practice.

Characterization of MHC induction by Mycoplasma fermentans (incognitus strain).

Mycoplasma fermentans (incognitus strain) is a recently identified new human pathogen and suspected cofactor in acquired immune deficiency syndrome. Because this organism appears to exert strong immunosuppressive properties of its own, we decided to investigate whether it was capable of inducing MHC class II expression, as we have observed for other species of mycoplasma. In this report we demonstrate that M. fermentans (incognitus strain) is capable of producing factors that increase MHC class II expression as well as MHC class I expression on the myelomonocytic cell line, WEHI-3 cells. We also present data showing that these mycoplasmal factors induce small, although significant, increases in MHC class I and II antigens on a mouse glioma cell line, G26-20, and MHC class II expression on the human monocyte cell lines, U-937 and HL-60. Using nuclear run-on analysis, we show that the mycoplasma-induced increase in MHC expression is at least partially due to an increase in transcription of the MHC genes. Furthermore, we show that the factor that mediates this activity is sensitive to protease treatment, indicating that it is, at least in part, protein. These results demonstrate that M. fermentans (incognitus strain) is capable of modulating the expression of immunologically important MHC genes in both murine and human cell lines, which may prove to be an important factor in the pathogenesis of this organism.

Ipsilateral ureteroureterostomy combined with ureteral reimplantation for treatment of disease in both ureters in a child with complete ureteral duplication.

Recurrent urinary tract infection was seen in a 3-year-old girl with a ureterocele at the lower end of the upper segment ureter and reflux into the lower segment ureter of a duplicated kidney on the left side. We combined ipsilateral ureteroureterostomy (end-to-side anastomosis) with reimplantation of the host, single ureter into the bladder distal to the anastomosis to reduce dilatation, correct the reflux and keep the patient free of infection without medication.

Mechanism of urocanase as studied by deuterium isotope effects and labeling patterns.

Nicotinamide adenine dinucleotide (NAD) dependent urocanase (4'-imidazolone-5'-propionate hydro-lyase, EC 4.2.1.49) from Pseudomonas putida was found to catalyze an exchange reaction between solvent and the 4'-hydrogen of urocanate or imidazolepropionate at a rate faster than that of overall deuterium was compared to unlabeled urocanate as a substrate, no isotope rate effect was noted. For examination of the possibility of an NAD+-mediated intramolecular hydride transfer of the 4'-hydrogen to a position on the side chain of oxoimidazolepropionate, the origins of hydrogen at positions 2 and 3 in the propionate chain were studied as a function of reaction time and extent of exchange of the 4'-hydrogen. No transfer of hydrogen from the 4' position to the side chain was observed, thereby eliminating mechanisms requiring hydride transfer via NADH between these positions. Catalytic rates in 1H2O vs. 2H2O revealed a 3-fold difference which was ascribed to a rate-limiting proton addition step. Similarly, a 5-fold decrease in Vmax was found for the reverse reaction when oxoimidazole[2,3-2H2]propionate was compared to unlabeled oxoimidazolepropionate. These data support a mechanism involving water addition across the conjugated double bond system of urocanate, rather than an internal oxidation--reduction process, yet NAD+ is required. A mechanism is proposed which uses electron delocalization in the imidazole nucleus, via an imidazole--NAD adduct, to facilitate water attack and subsequent formation of oxoimidazolepropionate.

Management of urinary calculous disease in patients with renal cysts: review of 12 years of experience in 18 patients.

During the last 12 years 18 patients with urinary calculi were found to have associated cystic renal disease. We herein describe the difficulties in diagnosing and in treating this group, which included patients with simple single renal cysts, multiple cysts of 1 or both kidneys and polycystic renal disease. Renal calculi may be caused by or perpetuated by renal cystic disease. After spontaneous passage or surgical removal renal calculi may recur as long as renal cysts continue to cause urinary stasis owing to obstruction and distortion of the renal calices. Superimposed renal infection may cause further difficulties in diagnosis and treatment. The timely removal of calculi and the relief of obstruction caused by the cysts and stones are emphasized. We further recommend the judicious use of antibiotics, correction of electrolyte disturbances and prolonged followup in an attempt to prevent future calculous disease.

Control of biodegradative threonine dehydratase inducibility by cyclic AMP in energy-restricted Escherichia coli.

To explain the requirement for anaerobic conditions in the induction of biodegradative L-threonine dehydratase in Escherichia coli, Crookes strain, measurements of cyclic AMP (cAMP) were made during aerobic and anaerobic growth and upon an aerobic-to-anaerobic transition. Internal cAMP levels were similar (5 to 10 muM) throughout exponential growth, whether aerobic or anaerobic, but only during anaerobiosis was threonine dehydratase synthesized. When an exponentially growing aerobic culture was made anaerobic, a sharp increase in internal cAMP was noted, reaching 300 muM within 10 min and declining thereafter to normal anaerobic levels. Threonine dehydratase synthesis was detected immediately after the attainment of peak cAMP levels and continued for several generations. A similar pattern but with less accumulation of cAMP and less threonine dehydratase production was also noted upon treatment of an aerobically growing culture with KCN. Pyruvate addition at the time of anaerobic shock severely affected both cAMP accumulation and threonine dehydratase synthesis; however, externally added cAMP could partially counter the pyruvate effect on enzyme synthesis. The conclusion was reached that conditions which resulted in a temporary energy deficit brought about the major accumulation of cAMP, and this elevated level served as a signal for initiation of threonine dehydratase synthesis to supply energy by the nonoxidative degradation of threonine.

Transcription of the murine class II Eb gene is regulated primarily at the level of transcriptional initiation.

The constitutive and inducible expression of MHC class II genes is known to be regulated by multiple upstream promoter elements. Transient transfection assays implicate the proximal promoter region as both necessary and sufficient for appropriate tissue-specific and inducible expression. However, transgenic mouse experiments suggest that additional control regions are important. In this study we tested the hypothesis that additional regulation of class II expression occurred at the level of RNA polymerase II elongation. Nuclear run-on analysis using single-stranded probes spanning the entire Eb gene was performed on a variety of class II-positive, class II-negative, and class II-inducible cell lines. The results demonstrate that, while there is not an even distribution of RNA polymerase along the gene, there is no evidence for a regulated block in elongation. These data further support the idea that the primary mechanism of class II gene regulation is at the level of transcriptional initiation.

Dorsovertical lumbotomy approach for surgery of upper urinary tract calculi.

During a 30-month interval 26 patients underwent pyelolithotomy or upper ureterolithotomy through the dorsovertical lumbotomy approach. The intraoperative course and postoperative performance were compared to those in a similar group of patients operated upon using the standard flank incision. Our analysis established the superiority of the dorsovertical lumbotomy incision for all factors evaluated, especially postoperative drainage, analgesic use and hospital stay. The surgical steps are described in detail and the relative contraindications are discussed.

Peptide-specific T cell clonal expansion in vivo following immunization in the eye, an immune-privileged site.

To visualize the primary antigen-specific T cell response to Ag introduced into the eye, we have used an adoptive transfer system in which a limiting number of OVA peptide (323-339)-specific T cells from a TCR-transgenic mouse were transferred into nonirradiated, syngeneic recipients and then tracked in vivo by staining for FACS analysis or immunohistochemistry with the clonotypic mAb KJ1-26. Following posterior chamber injection of Ag, KJ1-26+ cells accumulated primarily in the draining, submandibular lymph node (LN) within 3 days. Although reduced in number, by day 6 these cells were primarily in the paracortical regions and were able to proliferate and secrete IL-2 in response to Ag stimulation. In contrast, following i.v. injection of Ag, the KJ1-26+ cells accumulated in the paracortical regions of the LN to a comparable degree, but did not proliferate or secrete IL-2. The day 3 accumulation of KJ1-26+ cells in the submandibular LN was inhibited if the eye was removed within 5 h after injection of Ag. In the spleen, foci of KJ1-26+ cells were observed in the periarteriolar lymphoid sheaths at day 3; these were not observed to the same degree following other forms of immunization. These results demonstrate that the submandibular LN is the primary site for early clonal expansion of antigen-specific T cells following intraocular Ag administration and that these cells show changes consistent with immunity rather than tolerance.

In vivo behavior of peptide-specific T cells during mucosal tolerance induction: antigen introduced through the mucosa of the conjunctiva elicits prolonged antigen-specific T cell priming followed by anergy.

The mucosa of the conjunctiva is an important site of entry for environmental Ags as well as Ags emanating from the eye itself. However, very little is known about T cell recognition of Ag introduced through this important mucosal site. We have characterized the in vivo process of CD4 T cell recognition of Ag delivered via the conjunctival mucosa. Application of soluble OVA to the conjunctiva of BALB/c mice induced potent T cell tolerance. APC-presenting OVA peptide in vivo was only found in the submandibular lymph node and not in other lymph nodes, spleen, or nasal-associated lymphoid tissue. Similarly, in TCR transgenic DO11. 10 adoptive transfer mice, OVA-specific CD4+ T cell clonal expansion was only observed in the submandibular lymph node following conjunctival application of peptide. These experiments thus define a highly specific lymphatic drainage pathway from the conjunctiva. OVA-specific T cell clonal expansion peaked at day 3 following initiation of daily OVA administration and gradually declined during the 10-day treatment period, but remained elevated compared with nontreated adoptive transfer mice. During this period, the T cells expressed activation markers, and proliferated and secreted IL-2 in vitro in response to OVA stimulation. In contrast, these cells were unable to clonally expand in vivo, or proliferate in vitro following a subsequent OVA/CFA immunization. These results suggest that Ag applied to a mucosal site can be efficiently presented in a local draining lymph node, resulting in initial T cell priming and clonal expansion, followed by T cell anergy.