A pathological study of a mycobacterial infection in a cat caused by a variant with cultural characteristics between Mycobacterium tuberculosis and M bovis

A histological examination of a biopsy from a firm submandibular mass in a seven-year-old domestic short-haired cat revealed a granulomatous lymphadenitis associated with the presence of small numbers of acid-fast bacilli. The cat was euthanased and subjected to a detailed post mortem examination which revealed extensive granulomatous inflammation in the right and left bronchial, para-aortic, mesenteric and colic lymph nodes, with small or early lesions in the lung and Peyer's patches of the ileum. Mycobacteria were isolated from the submandibular, mesenteric and cervical lymph nodes. The bacilli reacted with a DNA probe specific for the tuberculosis complex, including Mycobacterium tuberculosis and M bovis, but had cultural characteristics intermediate between these two species. The pathological findings are compared with previous reports of mycobacterial infections in cats, and the public health implications are discussed.

A decision-supported outpatient practice system

We describe a Decision-supported Outpatient Practice (DOP) system developed and now in use at the Columbia-Presbyterian Medical Center. DOP is an automated ambulatory medical record system that integrates in-patient and ambulatory care data, and incorporates active and passive decision support mechanisms with a view towards improving the quality of primary care. Active decision support occurs in the form of event-driven reminders created within a remote clinical information system with its central data repository and decision support system (DSS). Novel features of DOP include patient specific health maintenance task lists calculated by the remote DSS. uses of a semantically structured controlled medical vocabulary to support clinical results review and provider data entry, and exploitation of an underlying ambulatory data model that provides for an explicit record of evolution of insight regarding patient management. Benefits, challenges, and plans are discussed.

Congenital abnormalities of the ovine paramesonephric ducts

A 15 month survey of ovine reproductive tracts was undertaken in slaughterhouses in southwest England. A total of 33506 tracts were examined; 23536 from lambs and 9970 from adults. In total, 3.4% of tracts were pregnant and 3.3% exhibited abnormalities. Twenty cases of uterus unicornis, six of uterus didelphys and 11 of segmental aplasia were encountered, such that partial aplasia of the paramesonephric ducts accounted for 3.3% of all abnormalities. Although developmental abnormalities of the ovine female genital system are relatively uncommon, a substantial proportion of these can be accounted for by development defects of the paramesonephric ducts.

Replication of equid herpesvirus 4 in endothelial cells and synovia of a field case of viral pneumonia and synovitis in a foal

Equid herpesvirus 4 (EHV-4) infection was diagnosed as the cause of interstitial pneumonia in a 6-week-old conventionally reared Welsh pony foal, by cocultivation and immunolabelling with specific monoclonal antibodies, EHV-4 specific amplification of viral DNA, and immunohistological examination of infected tissues. The case was novel in that replication of the EHV-4 isolate in endothelial cells and in the synovial epithelium was a feature. Restriction digests of this isolate were compared with those of seven respiratory and one abortigenic EHV-4 isolate, and no differences in restriction pattern were evident. The implications of these findings for the pathogenesis of EHV-4 infection are discussed.

Equine strangles modelled in mice

Small animal models of Streptococcus equi infection have been confined to parenteral injection of mice which subsequently develop a septicaemia. To devise a model of infection more closely resembling strangles, 4.9 x 10(6) cfu of S. equi were placed on the nares of C3H and Balb/c mice (fifteen of each). Compared with ten uninfected controls, infected mice sneezed more often and their daily weight gain was significantly reduced. Histopathological examination seven days after infection revealed varying degrees of nasopharyngeal and regional lymphoid pathology in twenty two mice. Eleven mice had an early or mild rhinitis in which the nasal epithelium presented microabscesses containing polymorphonuclear leucocytes. Another eleven mice had a suppurative rhinitis or pharyngitis associated in most with regional lymphadenitis; in two mice, abscessated lymph nodes had erupted into perinodal connective tissues. Two mice had a vestibular abscess. The suppurative rhinitis was associated with extensive necrosis of nasal propria which occasionally extended to conchal bone, resulting in osteomyelitis. Multiple bacterial abscesses were seen in the spleen of one mouse. Histological lesions were not detected in control mice or in eight infected mice. S. equi was re-isolated from the nares of fourteen of the twenty two affected mice but not from the eight unaffected challenged mice or control mice. The close resemblance of this model to strangles in horses may justify its further use for the investigation of pathogenesis and protective immunity.

DNA sequence analysis of spontaneous and gamma-radiation (anoxic)-induced lacId mutations in Escherichia coli umuC122::Tn5: differential requirement for umuC at G.C vs. A.T sites and for the production of transversions vs. transitions

Escherichia coli umuC122::Tn5 cells were gamma-irradiated (137Cs, 750 Gy, under N2), and lac-constitutive mutants were produced at 36% of the wild-type level (the umuC strain was not deficient in spontaneous mutagenesis, and the mutational spectrum determined by sequencing 263 spontaneous lacId mutations was very similar to that for the wild-type strain). The specific nature of the umuC strain's partial radiation mutability was determined by sequencing 325 radiation-induced lacId mutations. The yields of radiation-induced mutation classes in the umuC strain (as a percentage of the wild-type yield) were: 80% for A.T-->G.C transitions, 70% for multi-base additions, 60% for single-base deletions, 53% for A.T-->C.G transversions, 36% for G.C-->A.T transitions, 25% for multi-base deletions, 21% for A.T-->T.A transversions, 11% for G.C-->C.G transversions, 9% for G.C-->T.A transversions, and 0% for multiple mutations. Based on these deficiencies and other factors, it is concluded that the umuC strain is near-normal for A.T-->G.C. transitions, single-base deletions and possibly A.T-->C.G transversions; is generally deficient for mutagenesis at G.C sites and for transversions, and is grossly deficient in multiple mutations. Damage at G.C sites seems more difficult for translesion DNA synthesis to bypass than damage at A.T sites, and especially when trying to produce a transversion. The yield of G.C-->A.T transitions in the umuC strain (36% of the wild-type level) argues that abasic sites are involved in no more than 64% of gamma-radiation-induced base substitutions in the wild-type strain. Altogether, these data suggest that the UmuC and UmuD' proteins facilitate, rather than being absolutely required for, translesion DNA synthesis; with the degree of facilitation being dependent both on the nature of the noncoding DNA damage, i.e., at G.C vs. A.T sites, and on the nature of the misincorporated base, i.e., whether it induces transversions or transitions.

Distribution of equid herpesvirus-1 (EHV-1) in the respiratory tract of ponies: implications for vaccination strategies

Twelve adult ponies and 2 conventional foals were exposed to 10(6.6) TCID50 of Equid herpesvirus-1 (EHV-1), strain Ab4 and samples of respiratory tract tissues were recovered. Infectious virus in tissue homogenates was detected using susceptible cell monolayers and expression of viral antigens was monitored using indirect immunoperoxidase histochemistry of paraffin sections. The results illustrated the rapid dissemination of EHV-1 throughout the respiratory tract, with early replication in the lungs one day after exposure. Endothelial cell infection was prominent in all areas of the nasopharynx by Day 4 emphasising the role of endotheliotropism and viraemia in dissemination of this virus to sites of secondary replication. Clinical disease in the adult ponies was mild.

Distribution of equid herpesvirus-1 (EHV-1) in respiratory tract associated lymphoid tissue: implications for cellular immunity

Twelve adult ponies and 2 conventional foals were exposed intranasally to EHV-1, strain Ab4 (TCID50 10(-6.6) and samples of respiratory tract associated lymphoid tissues were recovered between 12 h and 13 days after infection. Infectious virus was detected in tissue homogenates using susceptible cell monolayers and expression of viral antigens was monitored using indirect immunoperoxidase histochemistry on paraffin sections. The results showed both infectious EHV-1 and viral antigens in respiratory tract associated lymph nodes 12 h after exposure. Infected leucocytes were identified morphologically as lymphocytes, monocytes, macrophages and plasma cells. The rapid intracellular localisation of EHV-1 in lymph nodes implies that cell mediated immunity is an important aspect of the equine response to this virus.

DNA sequence analysis of gamma-radiation (anoxic)-induced and spontaneous lacId mutations in Escherichia coli K-12

An extensive spectrum of ionizing radiation mutagenesis was determined by sequencing 318 137Cs gamma-radiation (anoxic)-induced episomal lacId mutations in Escherichia coli strain NR9102. The most commonly found radiation-induced mutations were base substitutions (44% transversions and 41% transitions). The radiation-induced spectrum consisted of: 23% G.C-->A.T, 18% A.T-->G.C, 17% G.C-->T.A, 14% G.C-->C.G, 8% A.T-->T.A, 6% A.T-->C.G, 8% single-base deletions, 5% multiple mutations, 3% multi-base deletions, and essentially no single- or multi-base additions. This spectrum compared better with spectra for other systems obtained by in vivo irradiation than with one obtained by in vitro irradiation. Multiple mutations, which were unique to the radiation-induced spectrum, generally consisted of one active and one closely linked silent mutation, and are suggested to result from an altered replication complex of reduced fidelity. Mutation rates were 4.1 x 10(-8) lac-constitutive mutations/gene/Gy and 1.2 x 10(-10) base substitutions/base pair/Gy. Thirty-two percent more radiation-induced mutations occurred at G.C vs. A.T base pairs. A strand asymmetry was noted for G.C-->C.G and A.T-->T.A transversions. A nearest-neighbor analysis showed that C (vs. A, G, or T), on either side of the mutation site, substantially enhanced most types of base substitutions. Similarly, G and C flanked both sides of single-base deletion sites twice as frequently as would be expected from the base composition of the mutation target. For comparative purposes, we sequenced 411 spontaneous lac-constitutive mutants of which 269 were lacId mutants, and there was good agreement between these and previously published mutational spectra. The spontaneous and radiation-induced mutational spectra differed substantially for virtually every class of mutation. For example, the set of spontaneous dominant lac-constitutive mutations contained many more mutations that did not map in the normal region for lacId mutations (i.e., 35% vs. 3%) and were presumed to be lacO-constitutive mutations. A sampling of these presumptive lacOc mutations was also sequenced: 17/22 (spontaneous) and 1/9 (radiation) were found to be lacOc long deletions, one from each set were base substitutions, and the remaining mutations showed the wild-type lacO sequence. Like the radiation-induced spectrum, the spontaneous spectrum showed enhanced mutagenesis at G.C sites, strand asymmetry, and enhanced mutagenesis when G or C were the nearest neighbors.

Evaluation of the conformational free energies of loops in proteins

In this paper we discuss the problem of including solvation free energies in evaluating the relative stabilities of loops in proteins. A conformational search based on a gas-phase potential function is used to generate a large number of trial conformations. As has been found previously, the energy minimization step in this process tends to pack charged and polar side chains against the protein surface, resulting in conformations which are unstable in the aqueous phase. Various solvation models can easily identify such structures. In order to provide a more severe test of solvation models, gas-phase conformations were generated in which side chains were kept extended so as to maximize their interaction with the solvent. The free energies of these conformations were compared to that calculated for the crystal structure in three loops of the protein E. coli RNase H, with lengths of 7, 8, and 9 residues. Free energies were evaluated with a finite difference Poisson-Boltzmann (FDPB) calculation for electrostatics and a surface area-based term for nonpolar contributions. These were added to a gas-phase potential function. A free energy function based on atomic solvation parameters was also tested. Both functions were quite successful in selecting, based on a free energy criterion, conformations quite close to the crystal structure for two of the three loops. For one loop, which is involved in crystal contacts, conformations that are quite different from the crystal structure were also selected. A method to avoid precision problems associated with using the FDPB method to evaluate conformational free energies in proteins is described.

The identification of 5-hydroxy-L-norvaline in cultures of pyridoxine auxotrophs of Escherichia coli B

Gc-ms and hplc have been employed to identify 5-hydroxy-L-norvaline (L-2-amino-5-hydroxypentanoic acid) in the culture fluids of pyridoxine-starved cultures of two pyridoxine auxotrophs of Escherichia coli B. The production of 5-hydroxynorvaline is shown to be secondary to pyridoxine starvation of the cultures, and the quantities of 5-hydroxynorvaline are similar to those of the common protein amino acids present in these cultures. This is the first time that 5-hydroxynorvaline has been identified as a product of bacterial metabolism.

Nutrient effects on growth and the production of 5-hydroxy-4-oxonorvaline by Streptomyces akiyoshiensis

5-Hydroxy-4-oxonorvaline (HON) was produced optimally by Streptomyces akiyoshiensis in media containing starch and casein supplemented with high concentrations of phosphate and magnesium sulfate; cultures grown at initial pH values between 6.3 and 6.6 yielded HON titres of 13-14 mM. Physiological analysis of HON production provided evidence that the excess inorganic constituents in this medium played an important role in optimizing production. In simple defined media buffered at pH 5.5-6.0 and inoculated with either a spore suspension or washed vegetative mycelium, formation of HON was less than one-third the amount produced in the starch-casein-salts medium. Production was markedly affected by the carbon and nitrogen sources used; media containing starch and potassium nitrate or aspartate supported the highest yields of HON. In starch-nitrate media, production was suppressed by excess nitrogen source, and the HON titre decreased 3-fold as the phosphate content was increased from 0.5 to 5 mM; growth was not appreciably altered. The results suggest that the high level of HON production in the complex starch-casein-salts medium is associated with sequestration of metabolic ammonium and reduced availability of phosphate through formation of the poorly soluble magnesium ammonium phosphate.

Replication of equid herpesvirus-1 in the vaginal tunics of colts following local inoculation

Equid herpesvirus-1 (EHV-1; Ab4 isolate) was inoculated unilaterally into the cavum vaginale of four pony colts under general anaesthesia. The animals were monitored daily for evidence of scrotal or testicular swelling and euthanased electively on days 3, 4, 6 and 12 after infection. Detailed pathological examination of the male genital tract was carried out. In animals examined at days 3 and 4 after infection, replication of EHV-1 was detected bilaterally in mesothelial and endothelial cells of the parietal and visceral vaginal tunics. The mesothelial infection had resolved by day 12 after infection, with no evidence of direct extension to deeper genital organs. None of the four colts showed significant scrotal or testicular swelling.

An immunohistological study of the uterus of mares following experimental infection by equid herpesvirus 1

Twelve Welsh Mountain pony mares in late gestation were infected intranasally with EHV-1 (AB4 isolate) at dose rates from 10(3) to 10(7.3) TCID50. This resulted in 3 cases of paresis, at Days 9, 10 and 12 after inoculation, and 5 abortions, at Days 6, 9, 18, 19 and 20. Euthanasia was performed between Days 6 and 21, with collection of uterine specimens for histopathology, virus isolation and immunoperoxidase staining from the pregnant horn, non-pregnant horn and body. EHV-1 replication in endometrial vessels was detected as early as Day 6 and was maximal at Days 9-11, when widespread thromboischaemic damage was present. By Days 15-19 in mares remaining pregnant, EHV-1 antigen expression in the endometrium was sparse, despite residual lesions but little associated thrombosis. Endometrial vascular pathology varied considerably in degree and extent, and no consistent predilection sites for replication within the uterus were apparent.

Modeling the anti-CEA antibody combining site by homology and conformational search

A model for an antibody specific for the carcinoembryonic antigen (CEA) has been constructed using a method which combines the concept of canonical structures with conformational search. A conformational search technique is introduced which couples random generation of backbone loop conformations to a simulated annealing method for assigning side chain conformations. This technique was used both to verify conformations selected from the set of known canonical structures and to explore conformations available to the H3 loop in CEA ab initio. Canonical structures are not available for H3 due to its variability in length, sequence, and observed conformation in known antibody structures. Analysis of the results of conformational search resulted in three equally probable conformations for H3 loop in CEA. Force field energies, solvation free energies, exposure of charged residues and burial of hydrophobic residues, and packing of hydrophobic residues at the base of the loop were used as selection criteria. The existence of three equally plausible structures may reflect the high degree of flexibility expected for an exposed loop of this length. The nature of the combining site and features which could be important to interaction with antigen are discussed.

Spontaneous mutagenesis: experimental, genetic and other factors

Spontaneous mutations are "the net result of all that can go wrong with DNA during the life cycle of an organism" (Glickman et al., 1986). Thus, the types and amounts of spontaneous mutations produced are the resultant of all the cellular processes that are mutagenic and those that are antimutagenic. It is not widely appreciated that the types and frequencies of spontaneous mutations change markedly with subtle changes in experimental conditions. All types of mutations are produced spontaneously, i.e., base substitutions, frameshifts, insertions and deletions. However, very few papers have appeared that are devoted exclusively to the study of the mechanisms of spontaneous mutagenesis, and of the subtle experimental factors that affect the types and frequencies of spontaneous mutations. This is unfortunate because spontaneous mutagenesis appears to play a major role in evolution, aging, and carcinogenesis. This review emphasizes subtle experimental variables that markedly affect the results of a spontaneous mutation experiment. A thorough understanding of these variables eliminates the need for a theory of "directed" mutagenesis. The intrinsic instability of DNA, and the types of normal metabolic lesions that are produced in DNA that lead to mutations via errors made in replication, repair, and recombination are reviewed, as is the genetic control of spontaneous mutagenesis. As with spontaneous mutagenesis, spontaneous carcinogenesis can also be considered to be the net result of all that can go wrong with DNA during the life of an organism.

Abortion of virologically negative foetuses following experimental challenge of pregnant pony mares with equid herpesvirus 1

From 1988 to 1991, 51 pregnant pony mares were challenged intranasally or by aerosol with an isolate of EHV-1 (AB4) originally recovered from a quadriplegic mare. This resulted in 32 abortions, occurring from 9 to 29 days after infection. In 14 of the early abortions (Days 9-14), EHV-1 was not demonstrated in the foetal tissues by virus isolation or immunostaining despite no other non-viral cause for the abortion being evident. Application of the polymerase chain reaction to foetal tissues from 9 of these cases also proved negative. One of the 14 mares was destroyed immediately after abortion, and post-mortem examination revealed severe and widespread vasculitis, thrombosis and secondary ischaemic damage in the endometrium with replication of EHV-1 in endothelial cells. These findings suggest that EHV-1 abortion can occur due to endometrial damage without the establishment of a foetal infection.

Properties of R-plasmid pEB017, which confers both enhanced UV-radiation resistance and mutability to wild-type, recA and umuC strains of Escherichia coli K12

The R-plasmid, pEB017, restored recombination ability to recA56 and conferred enhanced resistance to UV-radiation and enhanced UV-radiation mutability to wild-type, recA56 and umuC36 strains of Escherichia coli K12. Comparatively, pEB017 enhanced UV-radiation mutability in a umuC strain, and also enhanced UV-radiation and nitrofuran mutability in a wild-type strain several-fold more than did another R-plasmid, pKM101. Plasmid pEB017 also mediated about a 3-fold enhancement of the SOS induction of beta-galactosidase synthesis in a recA strain, compared with the normal recA+ gene of E. coli. A BamHI fragment of pEB017 DNA was cloned into plasmid vector pBR322 to yield pEB021. The BamHI fragment in pEB021 (3.5 kb) is about 170 bp longer between the BamHI and PstI sites on the left end of the recA-like fragment, compared with published data on a similarly cloned recA gene from E. coli. Plasmid pEB021 conferred enhanced resistance to UV-radiation and enhanced UV-radiation mutability in wild-type and recA strains, and restored recombination ability in a recA strain. The introduction of pEB021 into a umuC strain made the cells slightly more resistant to killing by UV-irradiation, and promoted a small amount of UV-mutability in an otherwise nonmutable strain. These results suggest that R-plasmid pEB017 has a recA-like gene that mediates the enhanced resistance to UV-radiation and enhanced UV-radiation mutability, but which seems different in several important aspects from the normal recA gene in E. coli.

Morphological autocorrelation transform: A new representation and classification scheme for two-dimensional images

A methodology based on mathematical morphology is proposed for efficient recognition of two-dimensional (2D) objects or shapes. It is based on the introduction a shape descriptor called the morphological autocorrelation transform (MAT). The MAT of an image is composed of a family of geometrical correlation functions (GCFs) which define its morphological covariance in a specific direction. The MAT is translation-, scale-, and rotation-invariant. It is shown that in most situations, a small subset of the MAT suffices for image representation. The characteristics and performance of a shape recognition system based on the MAT are investigated and analyzed. Computational complexity of the proposed morphological-based recognition system is examined. It is shown that shape properties, such as area, perimeter, and orientation, are readily derived from the MAT representation, and that the proposed system is well suited for shape representation and classification.

Involvement of RecB-mediated (but not RecF-mediated) repair of DNA double-strand breaks in the γ-radiation production of long deletions in Escherichia coli

Experiments were designed to determine the association between the repair of gamma-radiation-induced DNA double-strand breaks (DSB) and the induction of 700-1000 bp long deletions (Lac(-)----Lac+), base substitutions (leuB19----Leu+), and frameshifts (trpE9777----Trp+) in Escherichia coli K-12. Over the range of 2.5-20 krad, deletions were induced with linear kinetics, as has been shown for the induction of DSB, while the induction kinetics of base substitutions and frameshifts were curvilinear. Like the repair of DSB, deletion induction showed an absolute requirement for an intact recB gene as well as a dependency on the type of preirradiation growth medium; these requirements were not seen for base substitutions or frameshifts. In addition, about 80% of the spontaneous deletions were absent in the recB21 strain. A recC1001 mutation, which confers a 'hyper-Rec' phenotype, increased the rate of gamma-radiation-induced deletions as well as the low-dose production of base substitutions and frameshifts. A recF143 mutation increased the yield of gamma-radiation-induced deletions without increasing base substitutions or frameshifts. A mutS mutation markedly enhanced the gamma-radiation induction of frameshifts, and had a slight effect on base substitutions, but did not affect the induction of deletions. Resistance to gamma-irradiation and the capacity to repair DSB (albeit at about half the normal rate) were restored to the radiosensitive recB21 strain by the addition of the sbcB21 and sbcC201 mutations. However, the radioresistant recB sbcBC strain, which is recombination proficient via the RecF pathway, was still grossly deficient in the ability to produce deletions. A model for deletion induction as a by-product of the recB-dependent (Chi-dependent) repair of gamma-radiation-induced DSB is discussed, as is the inability to detect deletions in cells that use only the recF-dependent (Chi-independent) mechanism to repair DSB.