A model of microbial contamination of a water reservoir

A three year record of daily fecal coliform counts in a Massachusetts water reservoir has the appearance of an irregular time series punctuated by outbursts of varying duration. The pattern is described in terms of a probabilistic model where the fluctuations in the 'regular' and 'explosive' regimes are governed by two sets of probabilities. It has been assumed that the random oscillations has a lognormal distribution, and that once an explosion threshold has been exceeded the increments or decrements in the population size have fixed probability distributions. The threshold for triggering an outburst was estimated by examining the randomness of the autocorrelation function of the record after it is filtered to eliminate peaks of progressively increasing magnitude. Once the threshold has been identified, the mean and standard deviation of the underlying lognormal distribution could be estimated directly from remains found in the record after all the peaks were removed. The probabilities of an increment and decrement during the outbursts and their relative magnitudes could also be estimated using simple formulas. These estimated parameter values were then used to generate realistic records with known threshold levels, which were subsequently used to assess the procedure's feasibility and sensitivity.

Misacylation and editing by Escherichia coli valyl-tRNA synthetase: evidence for two tRNA binding sites

Valyl-tRNA synthetase (ValRS) has difficulty discriminating between its cognate amino acid, valine, and structurally similar amino acids. To minimize translational errors, the enzyme catalyzes a tRNA-dependent editing reaction that prevents accumulation of misacylated tRNA(Val). Editing occurs with threonine, alanine, serine, and cysteine, as well as with several nonprotein amino acids. The 3'-end of tRNA plays a vital role in promoting the tRNA-dependent editing reaction. Valine tRNA having the universally conserved 3'-terminal adenosine replaced by any other nucleoside does not stimulate the editing activity of ValRS. As a result 3'-end tRNA(Val) mutants, particularly those with 3'-terminal pyrimidines, are stably misacylated with threonine, alanine, serine, and cysteine. Valyl-tRNA synthetase is unable to hydrolytically deacylate misacylated tRNA(Val) terminating in 3'-pyrimidines but does deacylate mischarged tRNA(Val) terminating in adenosine or guanosine. Evidently, a purine at position 76 of tRNA(Val) is essential for translational editing by ValRS. We also observe misacylation of wild-type and 3'-end mutants of tRNA(Val) with isoleucine. Valyl-tRNA synthetase does not edit wild-type tRNA(Val)(A76) mischarged with isoleucine, presumably because isoleucine is only poorly accommodated at the editing site of the enzyme. Misacylated mutant tRNAs as well as 3'-end-truncated tRNA(Val) are mixed noncompetitive inhibitors of the aminoacylation reaction, suggesting that ValRS, a monomeric enzyme, may bind more than one tRNA(Val) molecule. Gel-mobility-shift experiments to characterize the interaction of tRNA(Val) with the enzyme provide evidence for two tRNA binding sites on ValRS.

Estimating the frequency of high microbial counts in commercial food products using various distribution functions

Industrial microbial count records usually form an irregular fluctuating time series. If the series is truly random or weakly autocorrelated, the fluctuations can be considered as the outcome of the interplay of numerous factors that promote or inhibit growth. These factors usually balance each other, although not perfectly, hence, the random fluctuations. If conditions are unchanged, then at least in principle the probability that they will produce a coherent effect, i.e., an unusually high (or low) count of a given magnitude, can be calculated from the count distribution. This theory was tested with miscellaneous industrial records (e.g., standard plate count, coliforms, yeasts) of various food products, including a dairy-based snack, frozen foods, and raw milk, using the normal, log normal, Laplace, log Laplace, Weibull, extreme value, beta, and log beta distribution functions. Comparing predicted frequencies of counts exceeding selected levels with those actually observed in fresh data assessed their efficacy. No single distribution was found to be inherently or consistently superior. It is, therefore, suggested that, when the probability of an excessive count is estimated, several distribution functions be used simultaneously and a conservative value be used as the measure of the risk.

Internal carotid artery hypoplasia presenting as anterior ischemic optic neuropathy

PURPOSE

To describe the occurrence of anterior ischemic optic neuropathy in a young woman with internal carotid artery hypoplasia.

METHODS

Case report with clinical and radiologic observations.

RESULTS

A 38-year-old woman suffered from a sudden, painless loss of vision in her right eye. The diagnosis of anterior ischemic optic neuropathy was based on the clinical course and appearance of the fundus. Doppler evaluation of the carotid arteries, computed tomography (CT) scan, magnetic resonance imaging (MRI), and CT angiogram all demonstrated internal carotid artery hypoplasia on the same side.

CONCLUSION

Although carotid artery disease (mainly atherosclerosis) is not a common predisposing factor for anterior ischemic optic neuropathy, our patient had an ipsilateral coexisting internal carotid artery hypoplasia and anterior ischemic optic neuropathy. We believe that the carotid artery anomaly might have contributed to the development of anterior ischemic optic neuropathy in this patient.

Mycoplasma fermentans in rheumatoid arthritis and other inflammatory arthritides

OBJECTIVE

To evaluate the association between infection with Mycoplasma fermentans (Mf) and rheumatoid arthritis (RA) and other inflammatory arthritides.

METHODS

Screening of synovial fluid samples (SF) for Mf was done by culture and by polymerase chain reaction (PCR) in 38 and 34 RA patients, respectively, 8 undifferentiated arthritis (UDA), 9 reactive arthritis (ReA), and in 40 other arthritides. The prevalence of antibodies to Mf in these SF was determined by both ELISA and immunoblotting (IB). Antibodies were measured also in sera of 88 RA patients, 28 ReA, 14 UDA, 71 other arthritides, and in 102 healthy blood donors.

RESULTS

All SF were culture-negative for Mf, while 7 SF were positive by PCR (6/34 RA and 1/8 UDA). SF from patients with other arthritides and ReA were PCR-negative. The prevalence of anti-Mf antibodies in SF of RA patients was significantly higher than in SF of other arthritides (p = 0.01). In 47% (17/38) of all RA (including the 6 PCR-positive patients), the level of antibodies to Mf in their SF was higher than that in sera, compared to 7.5% (3/40) in other arthritides (p = 0.0002). There was no significant difference in the prevalence of serum antibodies to Mf between patients with RA, other arthritides, and healthy controls. By IB with Mf sonicate, binding to Mf peptides P107, P48, and P29 was detected in SF of 7/11 RA patients but not in 11 patients with traumatic arthritis. Specific binding to Mf membrane lipoproteins was also more prevalent in SF of RA patients than in other arthritides (p = 0.038).

CONCLUSION

The finding that both Mf DNA and specific antibodies to Mf were present in the SF of RA patients suggests that in some RA patients Mf may play a role in initiating or perpetuating synovitis.

On estimating the probability of aperiodic outbursts of microbial populations from their fluctuating counts

The irregular sequence of counts of a microbial population, in the absence of observable corresponding environmental changes (e.g., temperature), can be regarded as reflecting the interplay of several unknown or random factors that favor or inhibit growth. Since these factors tend to balance one another, the fluctuations usually remain within bounds, and only by a coincidence--when all or most act in unison--does an 'outburst' occur. This situation can be represented mathematically as a sequence of independent random variables governed by a probability distribution. The concept was applied to reported microbial counts of ground meat and wastewater. It is found that the lognormal distribution could serve as a model, and that simulations from this model are indistinguishable from actual records. The parameters of the lognormal (or other) distribution can then be used to estimate the probability of a population outburst, i.e., an increase above a given threshold. Direct estimation of the outburst probability based on frequency of occurrence is also possible, but in some situations requires an impractically large number of observations. We compare the efficiency of these two methods of estimation. Such methods enable translation of irregular records of microbial counts into actual probabilities of an outburst of a given magnitude. Thus, if the environment remains 'stable' or in dynamic equilibrium, the fluctuations should not be regarded merely as noise, but as a source of information and an indicator of potential population outbursts even where obvious signs do not exist.

On modeling the irregular fluctuations in microbial counts

Daily or other periodic microbial counts in many foods, particularly ground meats, poultry, and raw milk, show an irregular fluctuating pattern. The cause of the fluctuations is the interplay of many random factors that tend to promote or inhibit microbial growth. Therefore, the actual size of a microbial population can vary randomly around a typical level or around a trend determined, for example, by seasonal variations or changing sanitary conditions. Fluctuations around a fixed level can often be modeled as a sequence of independent counts having a lognormal or other parametric distribution. The independence of the counts and the type of distribution can be established by standard statistical tests. Once selected, the distribution function can be used to estimate the probability of encountering a population in any given size range. The model can be modified to describe sequences that include zero counts, which are the result of the organisms' absence, or of the failure of the method to detect them. In the case of fluctuations around a trend, a modified version of the model can be used to estimate the probability of deviations from the trend. A more thorough modification is required in order to account for fluctuating patterns that include outbursts of appreciable duration, like those caused by massive contamination of a water reservoir.

Adenovirus-mediated p53 gene therapy: overview of preclinical studies and potential clinical applications

Disruption of p53 function through mutation, or other means, occurs very frequently in human cancer and is associated with an unfavorable prognosis in various cancers. Evidence from in vitro and in vivo transduction experiments have demonstrated that adenoviral-mediated expression of wild-type p53 suppresses the transformed phenotype of many cell types and potentiates the cytotoxicity of both chemotherapeutic agents and radiation therapy. Recently several phase I studies have evaluated the safety, biological effect and different routes of administration of adenoviral-mediated p53 gene therapy in various tumor types. These studies indicate that adenovirus-mediated p53 gene therapy and introduction of wild-type p53 into tumor cells represents a potentially valuable tool for the therapy of many types of human cancers. This review presents an overview of the most recent advances in the preclinical and clinical evaluation of adenoviral p53 gene therapy as well as the challenges that lay ahead forfuture clinical studies.

Synthetase recognition determinants of E. coli valine transfer RNA

We have studied the interactions between Escherichia coli tRNAVal and valyl-tRNA synthetase (ValRS) by enzymatic footprinting with nuclease S1 and ribonuclease V1, and by analysis of the aminoacylation kinetics of mutant tRNAVal transcripts. Valyl-tRNA synthetase specifically protects the anticodon loop, the 3' side of the stacked T-stem/acceptor-stem helix, and the 5' side of the anticodon stem of tRNAVal against cleavage by double- and single-strand-specific nucleases. Increased nuclease susceptibility at the ends of the anticodon- and T-stems in the tRNAVal.ValRS complex is indicative of enzyme-induced conformational changes in the tRNA. The most important synthetase recognition determinants are the middle and 3' anticodon nucleotides (A35 and C36, respectively); G20, in the variable pocket, and G45, in the tRNA central core, are minor recognition elements. The discriminator base, position 73, and the anticodon stem also are recognized by ValRS. Replacing wild-type A73 with G73 reduces the aminoacylation efficiency more than 40-fold. However, the C73 and U73 mutants remain good substrates for ValRS, suggesting that guanosine at position 73 acts as a negative determinant. The amino acid acceptor arm of tRNAVal contains no other synthetase recognition nucleotides, but regular A-type RNA helix geometry in the acceptor stem is essential [Liu, M., et al. (1997) Nucleic Acids Res. 25, 4883-4890]. In the anticodon stem, converting the U29:A41 base pair to C29:G41 reduces the aminoacylation efficiency 50-fold. This is apparently due to the rigidity of the anticodon stem caused by the presence of five consecutive C:G base pairs, since the A29:U41 mutant is readily aminoacylated. Identity switch experiments provide additional evidence for a role of the anticodon stem in synthetase recognition. The valine recognition determinants, A35, C36, A73, G20, G45, and a regular A-RNA acceptor helix are insufficient to transform E. coli tRNAPhe into an effective valine acceptor. Replacing the anticodon stem of tRNAPhe with that of tRNAVal, however, converts the tRNA into a good substrate for ValRS. These experiments confirm G45 as a minor ValRS recognition element.

Perspectives of nursing executives regarding ethical-economic issues

The authors grapple with the very real issue of how to allocate scarce health care resources while trying to hold down costs, especially in the face of changing federal and managed care reimbursement realities. Nurse executives (NEs) were surveyed in an attempt to discover their perspectives on a number of related ethical-economic issues. The NEs' responses to the entire "ethical-economic" survey were contrasted with answers offered to the same tool earlier by staff RNs. Among the questions raised was the impact of cost controls on staffing patterns. Not surprisingly, the staff nurses reported perceiving that budget cuts had a greater negative impact on staff positions and the quality of patient care than the nurse executives reported. Both groups were in favor of taxpayers covering a greater part of the cost of medically indigent care. When asked if they would be willing to pay higher taxes themselves, slightly less than half of the nurse executives answered in the affirmative while only 17% of the staff nurses indicated a similar willingness.

Intravitreal gas injection diminishes hyaluronic acid

OBJECTIVES

To determine if compression of the vitreous by an intraocular gas bubble diminishes the concentration of hyaluronic acid (NaHA).

MATERIALS AND METHODS

Eighteen albino rabbits had air, xenon or perfluoroethane (C2F6) injected into the vitreous to displace 12.5% to 90% of the vitreous volume. After the gas was absorbed, the vitreous was analyzed for NaHA by the Carbazole method (1, 13).

RESULTS

A 90% displacement diminished the NaHA concentration by 18.6%. Lesser displacements caused a lesser loss, but the differences are not significant.

CONCLUSION

Intraocular gas injections, both large and small, reduce the concentration of NaHA and destabilize the vitreous structure.

Massive pulmonary haemorrhage caused by leptospirosis successfully treated with nitric oxide inhalation and haemofiltration

A patient with leptospirosis who developed oliguric renal failure, massive pulmonary haemorrhage and respiratory failure is described. The patient's clinical condition and arterial oxygenation failed to improve despite vigorous supportive measures. Nitric oxide inhalation and haemofiltration resulted in a marked clinical improvement and subsequent full recovery. We suggest that the addition of haemofiltration and nitric oxide inhalation therapy should be considered in patients with pulmonary haemorrhage and renal failure caused by leptospirosis, in whom conventional therapy fails.

Dermatomyositis and peritoneal papillary serous carcinoma

We describe an unusual case of peritoneal papillary serous carcinoma (PPSC) arising in a female patient with dermatomyositis (DM). Despite periodic extensive searches for an underlying malignancy, no malignancy had been detected in this patient during the first 2.5 years after the diagnosis of DM. It was only when the patient presented with pleural effusion and ascites that the underlying intra-abdominal malignancy was detected by laparoscopy. Treatment with four cycles of pre-operative chemotherapy (taxol and cisplatin) resulted in tumor regression with amelioration in the muscular manifestation of the DM, but without parallelic amelioration in the skin manifestations of the DM. Explorative laparotomy confirmed the presence of papillary serous carcinoma in the omentum, surface of the left ovary and the retroperitoneal lymph nodes, and established the diagnosis of PPSC. Following two cycles of postoperative chemotherapy, the patient is alive with no evidence of internal malignancy. However, although muscle strength and enzymes have remained normal, no effect on the skin manifestation of DM has been observed. This case illustrates that, alongside the more frequently occurring ovarian carcinoma, PPSC should also be considered in the differential diagnosis of the underlying malignancy that may occur in the female patient with DM.

Recognition of the universally conserved 3'-CCA end of tRNA by elongation factor EF-Tu

Escherichia coli tRNA(Val) with pyrimidine substitutions for the universally conserved 3'-terminal adenine can be readily aminoacylated. It cannot, however, transfer valine into polypeptides. Conversely, despite being a poor substrate for valyl-tRNA synthetase, tRNA(Val) with a 3'-terminal guanine is active in in vitro polypeptide synthesis. To better understand the function of the 3'-CCA sequence of tRNA in protein synthesis, the effects of systematically varying all three bases on formation of the Val-tRNA(Val):EF-Tu:GTP ternary complex were investigated. Substitutions at C74 and C75 have no significant effect, but replacing A76 with pyrimidines decreases the affinity of valyl-tRNA(Val) for EF-Tu:GTP, thus explaining the inability of these tRNA(Val) variants to function in polypeptide synthesis. Valyl-tRNA(Val) terminating in 3'-guanine is readily recognized by EF-TU:GTP. Dissociation constants of the EF-Tu:GTP ternary complexes with valine tRNAs having nucleotide substitutions at the 3' end increase in the order adenine < guanine < uracil; EF-Tu has very little affinity for tRNA terminating in 3' cytosine. Similar observations were made in studies of the interaction of 3' end mutants of E. coli tRNA(Ala) and tRNA(Phe) with EF-Tu:GTP. These results indicate that EF-Tu:GTP preferentially recognizes purines and discriminates against pyrimidines, especially cytosine, at the 3' end of aminoacyl-tRNAs.

Antibodies to mycoplasma fermentans in HIV-positive heterosexual patients: seroprevalence and association with AIDS

There are conflicting reports concerning the prevalence of Mycoplasma fermentans in HIV-positive patients and its association with AIDS. Serum antibodies to M. fermentans were measured by a modified immunoblotting technique in 48 HIV-positive heterosexual patients and in 30 HIV-negative heterosexual controls. Antibodies to M. fermentans were detected in 19 (40%) of HIV-positive patients and in three (10%) of the HIV-negative controls (P = 0.01). The prevalence of antibodies to Mycoplasma hominis and to Ureaplasma urealyticum was similar in both groups. In the HIV-positive group, 16/19 (84%) M. fermentans-positive patients developed AIDS, compared to eight of 29 (28%) M. fermentans-negative patients (P = 0.0004). The HIV-positive patients with antibodies to M. fermentans had a lower CD4+ cell count and a higher prevalence of antibodies to the other mycoplasma tested (P = 0.007 and P = 0.03, respectively), as compared to the patients without antibodies to M. fermentans. These findings may suggest that the presence of antibodies to M. fermentans indicate an opportunistic infection. Of the 19 M. fermentans-positive patients, 11 were positive on the first examination, and eight became positive during the follow-up period. Seven out of these eight patients developed antibodies to M. fermentans before the development of AIDS. Therefore, the possibility exists that M. fermentans might influence the development of AIDS.

Role of acceptor stem conformation in tRNAVal recognition by its cognate synthetase

Although the anticodon is the primary element in Escherichia coli tRNAValfor recognition by valyl-tRNA synthetase (ValRS), nucleotides in the acceptor stem and other parts of the tRNA modulate recognition. Study of the steady state aminoacylation kinetics of acceptor stem mutants of E.coli tRNAValdemonstrates that replacing any base pair in the acceptor helix with another Watson-Crick base pair has little effect on aminoacylation efficiency. The absence of essential recognition nucleotides in the acceptor helix was confirmed by converting E.coli tRNAAlaand yeast tRNAPhe, whose acceptor stem sequences differ significantly from that of tRNAVal, to efficient valine acceptors. This transformation requires, in addition to a valine anticodon, replacement of the G:U base pair in the acceptor stem of these tRNAs. Mutational analysis of tRNAValverifies that G:U base pairs in the acceptor helix act as negative determinants of synthetase recognition. Insertion of G:U in place of the conserved U4:A69 in tRNAValreduces the efficiency of aminoacylation, due largely to an increase in K m. A smaller but significant decline in aminoacylation efficiency occurs when G:U is located at position 3:70; lesser effects are observed for G:U at other positions in the acceptor helix. The negative effects of G:U base pairs are strongly correlated with changes in helix structure in the vicinity of position 4:69 as monitored by19F NMR spectroscopy of 5-fluorouracil-substituted tRNAVal. This suggests that maintaining regular A-type RNA helix geometry in the acceptor stem is important for proper recognition of tRNAValby valyl-tRNA synthetase.19F NMR also shows that formation of the tRNAVal-valyl-tRNA synthetase complex does not disrupt the first base pair in the acceptor stem, a result different from that reported for the tRNAGln-glutaminyl-tRNA synthetase complex.

Septic arthritis due to bacteroides fragilis after pilonidal sinus resection in a patient with rheumatoid arthritis

Bacteroides fragilis is a rare cause of septic arthritis. Most patients with B. fragilis septic arthritis have a chronic joint disease, particularly rheumatoid arthritis, and sources of infection are lesions of the gastrointestinal tract and the skin. We report a 69-year-old male, who developed B. fragilis septic arthritis after pilonidal sinus resection. High level of suspicion of development B. fragilis septic arthritis must be present in patients with chronic joint disease in whom gastrointestinal or skin surgery was previously performed.

Localization of the major ethidium bromide binding site on tRNA

Binding of ethidium bromide to Escherichia coli tRNAVal and an RNA minihelix based on the acceptor stem and T-arm of tRNAVal was investigated by 19F and 1H NMR spectroscopy of RNAs labeled with fluorine by incorporation of 5-fluorouracil. Ethidium bromide selectively intercalates into the acceptor stem of the tRNAVal. More than one ethidium bromide binding site is found in the acceptor stem, the strongest between base pairs A6:U67 and U7:A66. 19F and 1H spectra of the 5-fluorouracil-substituted minihelix RNA indicate that the molecule exists in solution as a 12 base-paired stem and a single-stranded loop. Ethidium bromide no longer intercalates between base pairs corresponding to the tRNAVal acceptor stem in this molecule. Instead, it intercalates between base pairs at the bottom of the long stem-loop structure. These observations suggest that ethidium bromide has a preferred intercalation site close to the base of an RNA helical stem.

Hyperreactive malarial splenomegaly and AIDS: proguanil prevents recurrent pneumonia

An Ethiopian immigrated to Israel and gave a positive test result for human immunodeficiency virus. Soon after, he was thrice admitted to hospital in 3 months for severe pneumonia. Acquired immunodeficiency syndrome was diagnosed, as was hyperreactive malarial splenomegaly (HMS). Thereafter, during maintained proguanil treatment for HMS, the patient remained well for 16 months. Then, after another pneumonic illness, pneumococcal vaccine was administered. Proguanil was maintained for another 10 months and, despite declining CD4 cell counts, good health continued for a further 18 months.

Postoperative complications after splenectomy for hematologic malignancies

OBJECTIVE

The authors analyzed the frequency and character of postoperative complications after splenectomy in patients with hematologic malignancies, and correlated these findings with preoperative conditions that could have predicted their outcome.

SUMMARY BACKGROUND DATA

Splenectomy is performed for hematologic malignancies for diagnostic and therapeutic indications. The role of splenectomy for lymphoproliferative and myeloproliferative malignancies is complex and sometimes controversial.

METHODS

The medical records of 135 patients undergoing splenectomies for hematologic malignancies at Roswell Park Cancer Institute from January 1, 1984 to December 31, 1993 were reviewed retrospectively. These included Hodgkin's disease (HD), hairy cell leukemia (HCL), non-Hodgkin's lymphoma (NHL), chronic lymphocytic leukemia (CLL), chronic myelogenous leukemia (CML), and a miscellaneous group.

RESULTS

The overall postoperative complication and mortality rates for all patients were 52% and 9%, respectively. The complication rate was 63% for patients whose spleens weighed greater than 2000 g, and 29% for patients whose spleens weighed less than 2000 g (p = 0.001). Seventy-three percent of the postoperative deaths were due to septic complications, only one of which was caused by an encapsulated organism. Complications occurred in less than 20% of patients with the diagnosis of HD and HCL; more than 50% of patients with NHL, CLL, and CML suffered postoperative complications.

CONCLUSIONS

Splenectomy performed in patients with hematologic malignancies is a potentially morbid procedure. Splenic size was the only preoperative factor found to be predictive of postoperative complications. The complication rate differed significantly between the different diagnostic subgroups.

The in vivo bioactivity of vascular endothelial growth factor/vascular permeability factor is independent of N-linked glycosylation

The carbohydrate moieties of glycoprotein hormones or growth factor molecules may have a variety of effects that impact biological potency. Vascular endothelial growth factor (VEGF), also known as vascular permeability factor (VPF), is a 45 kD heparin-binding, endothelial cell (EC) specific mitogen with a putative N-linked glycosylation site. Recent studies have shown that VEGF/VPF may successfully augment collateral development in animal models of myocardial and hindlimb ischemia. The extent to which glycosylation of the 75 asparagine site affects the angiogenic properties of VEGF/VPF has not been studied in vivo. Specifically unaddressed to date is the concern that nonglycosylated VEGF/VPF may be less stable, and therefore characterized by a shorter half-life, reducing its utility for therapeutic angiogenesis. Accordingly, the purpose of this study was to investigate the extent to which posttranslational modification, specifically glycosylation, mofies the angiogenic properties of VEGF/VPF in vivo. Glycosylated (g+) recombinant human VEGF165 was purified from media conditioned by Chinese hamster ovary (CHO) cells. Nonglycosylated (g-) VEGF165 was expressed, purified and refolded from E. coli. The purity of both materials was assessed by silver-stained SDS/PAGE and characterized by the presence of a single amino terminal sequence as indicated by Edman degradation. Tryptic mapping by reverse-phase HPLC confirmed that the potential glycosylation site at 75 asparagine was occupied by N-linked carbohydrate for the Chinese hamster ovary-derived VEGF/VPF, but not for E. coli-derived VEGF/VPF. The mitogenic effects of Chinese hamster ovary-derived (g+) VEGF165 and E. coli-derived (g-) VEGF165 wre studied in vitro using microvascular EC. At concentrations of VEGF/VPF ranging from 10(-4) to 10(2) nM, both produced similar concentration-dependent effects on EC proliferation. For in vivo studies, (g-) (n = 8) and (g+) (n = 8) formulations of VEGF/VPF were administered to New Zealand white rabbits with unilateral hindlimb ischemia. For (g-) versus (g+) VEGF/VPF-treated groups, respectively, calf blood pressure ratio was 0.40 +/- 0.04 versus 0.37 +/- 0.04; angiographic score (of collateral vessels) was 0.37 +/- 0.04 versus 0.35 +/- 0.04; capillary density (capillaries/mm2) at necropsy was 246.9 +/- 21.5 versus 253.9 +/- 18.8; and tissue perfusion (colored microspheres) was 92.8 +/- 5.5 versus 90.30 +/- 13.47 (all p = ns). Moreover, intravascular Doppler-based analyses of resting, maximum, and endothelium-dependent flow was similar for (g-) and (g+) VEGF/VPF. These in vitro and in vivo findings establish that the potential for VEGF/VPF to stimulate therapeutic angiogenesis persists unaltered in the nonglycosylated state.

A case report. Ectopic molars that cause osteomeatal complex obstruction

During a routine dental examination, a general dentist noticed facial asymmetry in a 42-year-old man. Dental radiography suggested a pathological condition in the sinuses. The dentist referred the patient to a head and neck surgeon for further examination. Computed tomography demonstrated ectopic molars in the maxillary sinuses blocking drainage of the sinuses.

Perspectives of practicing nurses on ethical issues in health care economics

Perspectives of nurses working in seven hospitals across the United States are described. Most nurses believed that all people should have equal access and quality of health care. However, most nurses were unwilling to pay more taxes or donate time to achieve these goals.

Infection of the amniotic cavity with Ureaplasma urealyticum in the midtrimester of pregnancy

The purpose of this study was to determine the clinical significance of invasion of the amniotic fluid (AF) with Ureaplasma urealyticum in the midtrimester of pregnancy. Amniotic fluid and cervical swabs obtained from 214 asymptomatic women in the midtrimester of pregnancy (16-20 weeks) were cultured for U urealyticum and Mycoplasma hominis. Inoculum size was determined by quantitative culture. Six of the 214 women (2.8%) had Ureaplasma in high titers in the AF. The pregnancy outcomes of 129 women were determined. Adverse pregnancy outcome occurred more frequently in women with a positive AF culture than in women with a negative AF culture (3/6 [50%] vs. 15/123 [12%], respectively; P = .035). We conclude that infection of the amniotic cavity with U urealyticum can be present in asymptomatic patients in the midtrimester of pregnancy and is a significant risk factor for spontaneous preterm labor and delivery. These observations suggest that routine culture of AF at the time of midtrimester amniocentesis can identify the group of patients at risk for a poor pregnancy outcome.

An institutional review of sarcomas of the large and small intestine

BACKGROUND

This study was done to review the institutional experience with the treatment of sarcoma of the small or large intestine.

STUDY DESIGN

Thirty-nine patients admitted between the years 1959 and 1987, with a diagnosis of sarcoma of the small or large bowel form the basis of this review.

RESULTS

At referral, 74 percent of the patients presented with peritoneal sarcomatosis. Only six patients underwent complete resection. The overall five-year survival rate was 20 percent. Patients with low grade tumors had median and five-year survival rates of 33.3 months and 44 percent, respectively, while patients with high grade tumors had median and five-year survival rates of 22.4 months and zero percent, respectively, p = 0.01. Patients undergoing complete resection had a median survival period of 33.3 months, while patients receiving less than complete resection had a median survival period of 15.4 months, p = 0.003. Factors found to be significant by multifactorial analysis included tumor size, grade, stage at presentation, and invasion of adjacent organs.

CONCLUSIONS

Sarcoma of the small and large bowel is an uncommon entity. Survival rates are relatively poor. Aggressive surgical intervention is the mainstay of therapy.

Antibodies to Ureaplasma urealyticum in women with intraamniotic infection and adverse pregnancy outcome

OBJECTIVE

To determine the association between antibody response to Ureaplasma urealyticum and pregnancy outcome in women with ureaplasmal invasion of the amniotic cavity.

METHODS

A cross section study was performed in our high risk pregnancy unit. Three groups of pregnant women were identified: 1) 271 women at the midtrimester of pregnancy (16-20 weeks), who underwent transabdominal amniocentesis for genetic indications 2) 161 consecutive women admitted with preterm labor and intact membranes. 3) 118 consecutive patients with preterm premature rupture of membranes. Amniotic fluids were cultured for Ureaplasma urealyticum, Mycoplasma hominis and also for other aerobic and anaerobic bacteria. Serum antibodies to Uu were measured by a specific enzyme-linked-immunosorbent-assay.

RESULTS

The prevalence of positive AF cultures with Uu in the 3 study groups was 2.9%, 4.3% and 17.8%, and the prevalence of antibodies to Uu in the AF-colonized patients was 50%, 86% and 57%, respectively. Adverse pregnancy outcome (preterm birth, low birth weight or fetal death) among all AF colonized women, was significantly higher in patients with antibodies to Uu than in those without antibodies; preterm delivery 90% vs. 43%, and low birth weight infants or fetal death 85% vs. 28%, p = 0.006 and 0.001 respectively.

CONCLUSION

Women with intraamniotic infection with Uu and elevated levels of antibodies to Uu, had a higher rate of preterm delivery, and low birthweight infants/fetal death than those without antibody to Uu.

Ureaplasma urealyticum cervical colonization as a marker for pregnancy complications

OBJECTIVES

To determine the clinical significance of cervical colonization with (Ureaplasma urealyticum (Uu) and its possible relationship to pregnancy outcome.

METHODS

Cervical cultures for Uu and serum antibodies to Uu were determined in four groups of pregnant women: (1) 117 women who underwent mid-trimester amniocentesis; (2) 47 women with preterm labor and intact membranes; (3) 34 women with preterm premature rupture of membranes; and (4) a control group of 315 healthy women with normal pregnancies. Statistical methods used were the chi-square and Fisher's exact tests.

RESULTS

A significant increase in the cervical colonization rate with Uu was detected in all study groups (62%, 77% and 74%, respectively) when compared with the control group (42%). Women at mid-trimester of pregnancy with a positive cervical culture and high levels of antibodies, had a higher rate of pregnancy complications than those with a negative culture and absence of antibodies (62 vs. 28%, respectively; P = 0.0006).

CONCLUSION

Cervical colonization with Uu when associated with elevated titers of antibodies to Uu, may serve as a marker for the identification of a subpopulation of women who are at high risk for the development of pregnancy complications.

Mycoplasma genitalium in the joints of two patients with arthritis

Mycoplasma genitalium was sought in synovial fluids from 13 patients, of whom five had Reiter's syndrome, four had rheumatoid arthritis, and one each had systemic lupus erythematosus, psoriatic arthritis, rheumatic fever and undefined arthritis. The mycoplasma was detected by a PCR assay in the knee joint of a 25-year-old man with Reiter's syndrome, from whom urethral ureaplasmas were isolated and whose synovial fluid mononuclear cells responded to ureaplasmal antigens in a proliferation assay. Mycoplasma genitalium was also detected in the knee joint during an exacerbation of arthritis in a 58-year-old man who had had seronegative juvenile polyarthritis that had evolved to seronegative rheumatoid arthritis.

Functional transfer RNAs with modifications in the 3'-CCA end: differential effects on aminoacylation and polypeptide synthesis

The trinucleotide CCA sequence is present at the 3' terminus of all mature tRNAs. Despite this high degree of conservation, we have been able to prepare in vitro transcripts of Escherichia coli tRNA(Val) with altered 3' termini that are readily aminoacylated and can function in polypeptide synthesis. Replacement of the 3'-terminal adenosine with either cytidine or uridine yields a tRNA(Val) variant that retains almost full aminoacylation activity, having specificity constants (Vmax/Km) 40-50% that of wild-type tRNA(Val). The tRNA(Val) variant with a 3'-terminal guanosine remains fully chargeable but is a poor substrate for valyl-tRNA synthetase, largely as the result of a decrease in the catalytic constant. End-group analysis revealed the absence of adenosine at the 3' end of the tRNA(Val) mutants and identified the nucleotide expected from the sequence of the DNA template as the predominant 3'-terminal residue; Val-cytidine was isolated from the aminoacylated C76 mutant. Val-tRNA(Val) with 3'-CCG is active in poly(U,G)-directed (Val, Phe) copolypeptide synthesis, whereas the tRNA(Val) mutants terminating in 3'-CCC and 3'-CCU, which are readily aminoacylated, are inactive. The differential effects of nucleotide substitution on aminoacylation and polypeptide synthesis suggest that the universally conserved 3'-CCA end of tRNAs is monitored at two or more steps in protein synthesis that have different nucleotide recognition specificities.

Nucleoside modifications stabilize Mg2+ binding in Escherichia coli tRNA(Val): an imino proton NMR investigation

The structures of in vitro transcribed Escherichia coli tRNA(Val), which lacks base modifications, and the native tRNA, which contains them, are very similar in the presence of excess Mg2+ (Kintanar, Yue, and Horowitz, unpublished results). To further probe the effects of base modifications on the structure of tRNA, the Mg2+ ion dependence of the downfield region of the 1H NMR spectrum of in vitro transcribed E. coli tRNA(Val) in aqueous phosphate buffer was investigated. The spectra indicate a remarkable conformational change in unmodified E. coli tRNA(Val) coincident with binding or release of Mg2+. Assignment of the imino proton resonances in the low Mg2+ form of the tRNA transcript allows a detailed description of the conformational change. There is near total disruption of the D stem and tertiary interactions in the absence of bound Mg2+. A new strong interaction between the U67-A6 base pair and the G50-U64 wobble pair is observed, indicating a substantial structural rearrangement at the junction of the acceptor and T stems. The binding constants of the strong Mg2+ binding sites in the D loop and near the D stem in unmodified tRNA(Val) are at least 2 orders of magnitude less than in tRNAVal containing base modifications. The metal ion binding site in the anticodon loop is somewhat stronger than metal ion binding sites in the D loop and stem in unmodified tRNA(Val), but it is still weaker than all strong Mg2+ binding sites in native tRNA(Val). Thus, one role of the base modifications found in tRNA is to stabilize or strengthen the Mg2+ binding sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Ureaplasma urealyticum in Reiter's syndrome

OBJECTIVE

To evaluate the role of Ureaplasma urealyticum (Uu) in the pathogenesis of Reiter's syndrome (RS).

METHODS

Infection with Uu was determined in 31 patients with RS and 28 patients with other arthritides by urethral, cervical and synovial fluid (SF) culture and by measuring anti-Uu serum antibody. Infection with Chlamydia trachomatis was determined by examining SF by a direct immunofluorescence technique, by a polymerase chain reaction and by measuring anti-C. trachomatis serum antibody. The proliferative response of SF and peripheral blood mononuclear cells (PBMC) to Uu antigens in patients with RS was compared to that of a control group. The effect that treatment of 6 patients with RS with ciprofloxacin had on repeated cultures, on titer of anti-Uu antibody and on mononuclear cell reactivity was measured sequentially.

RESULTS

The colonization rate of Uu in patients with RS (74%) was significantly greater than in patients with other arthritides (14%). Genital C. trachomatis isolation and serum anti-C. trachomatis antibody were uncommon in both groups (11 and 13%, respectively). SF mononuclear cells of the patients with RS proliferated specifically in response to Uu antigens [up to 6.9 stimulation index (SI)], as did their PBMC (up to 14.5 SI). In some patients, high anti-Uu antibody titers were measured in the serum. Clinical remission was observed in 4 of 6 patients and correlated with eradication of Uu, decrease in antibody titers and disappearance of mononuclear cell reactivity to Uu antigens.

CONCLUSION

Our findings suggest that Uu might be a causative agent or a trigger in the development of sexually acquired RS.

Effect of nucleoside modifications on the structure and thermal stability of Escherichia coli valine tRNA

Transfer RNA transcribed in vitro lacks the base modifications found in native tRNA. To understand the effect of base modifications on the structure of tRNA, the downfield region of the 1H NMR spectrum of in vitro transcribed E coli tRNAVal in aqueous phosphate buffer in the presence of excess Mg2+ was investigated. The resonances of all imino protons involved in hydrogen bonds in the helical stem regions and in tertiary interactions were assigned using two-dimensional nuclear Overhauser enhancement spectroscopy (NOESY) and one-dimensional difference nuclear Overhauser effect (NOE) methods. In addition, some aromatic C2 and C8 proton resonances as well as one amino proton resonance were assigned. The chemical shifts of the assigned resonances of unmodified E coli tRNAVal were compared with those of the native tRNA molecule under similar solution conditions. The similarity of the NMR data for unmodified and modified tRNA indicates that the in vitro transcribed tRNA has nearly the same solution structure as the native molecule in the presence of excess Mg2+. The only significant differences were the chemical shifts of resonances corresponding to protons in (or interacting with) bases, indicating the possibility of local structural perturbations. The thermal stability of E coli modified and unmodified tRNAVal in the presence of Mg2+ was also investigated by analyzing the temperature dependence of the imino proton spectra. Several tertiary interactions involving modified nucleosides in native E coli tRNAVal are less stable in the absence of base modifications.

Probing structural differences between native and in vitro transcribed Escherichia coli valine transfer RNA: evidence for stable base modification-dependent conformers

Structural differences between native (modified) and in vitro transcribed (unmodified) Escherichia coli tRNA(Val) were explored by comparing their temperature-absorbance profiles as a function of magnesium ion concentration and by probing their solution conformation with single- and double-strand-specific endonucleases. In vitro transcribed tRNA(Val) has a less ordered structure as monitored by thermal melting profiles; its Tm is appreciably lower than that of native tRNA(Val) at all Mg2+ concentrations. Structure probing experiments with nuclease S1 and ribonuclease V1 show that the unmodified tRNA(Val) transcript is more susceptible to nuclease attack at low Mg2+ concentrations, particularly in the D- and T-loops, indicative of at least a partial disruption of D-loop/T-loop interactions. These experiments also provide evidence for temperature-dependent alternative conformations of the anticodon loop of native tRNA(Val). Modified nucleosides are essential for the stability of these conformers; they cannot be detected in the unmodified in vitro transcript. The observations suggest that post-transcriptional modifications in tRNA allow the adoption of unique conformations and act to stabilize those that are biologically active.

In vitro transcription of transfer RNAs with 3'-end modifications

It is difficult to modify the 3'-end of RNA transcribed in vitro from recombinant plasmid or phagemid DNA because of the need to retain a restriction endonuclease recognition site at the downstream end of the template in order to linearize the DNA before transcription. To avoid limitations on the 3'-sequence of RNA transcripts, we have modified a template-containing phagemid by inserting a FokI site outside the RNA gene sequence, positioned to cleave the template DNA to yield the desired 3' terminus. We demonstrate that this phagemid is an efficient template for tRNA transcription and use it to prepare mutants of Escherichia coli tRNA(Val) with modifications at the 3'-CCA end. Phagemids containing a FokI site should be suitable for in vitro transcription of large quantities of RNA of any length and with an unlimited variety of 3'-terminal sequences.

[Aneurysmal bone cyst of a lumbar vertebra in a child]

An aneurysmal cyst of the 3rd lumbar vertebra was diagnosed in a 6-year-old girl. She presented with right loin pain and a palpable mass in the region of the second and third lumbar vertebrae. X-ray of the vertebrae, but not computerized tomography, was characteristic for the tumor. The diagnosis was confirmed by histologic examination. Aneurysmal cyst of the vertebra is rare in children.

Correlations between fluorine-19 nuclear magnetic resonance chemical shift and the secondary and tertiary structure of 5-fluorouracil-substituted tRNA

To complete assignment of the 19F nuclear magnetic resonance (NMR) spectrum of 5-fluorouracil-substituted Escherichia coli tRNA(Val), resonances from 5-fluorouracil residues involved in tertiary interactions have been identified. Because these assignments could not be made directly by the base-replacement method used to assign 5-fluorouracil residues in loop and stem regions of the tRNA, alternative assignment strategies were employed. FU54 and FU55 were identified by 19F homonuclear Overhauser experiments and were then assigned by comparison of their 19F NMR spectra with those of 5-fluorouracil-labeled yeast tRNA(Phe) mutants having FU54 replaced by adenine and FU55 replaced by cytosine. FU8 and FU12, were assigned from the 19F NMR spectrum of the tRNA(Val) mutant in which the base triple G9-C23-G12 substituted for the wild-type A9-A23-FU12. Although replacement of the conserved U8 (FU8) with A or C disrupts the tertiary structure of tRNA(Val), it has only a small effect on the catalytic turnover number of valyl-tRNA synthetase, while reducing the affinity of the tRNA for enzyme. Analysis of the 19F chemical shift assignments of all 14 resonances in the spectrum of 5-fluorouracil-substituted tRNAVal indicated a strong correlation to tRNA secondary and tertiary structure. 5-Fluorouracil residues in loop regions gave rise to peaks in the central region of the spectrum, 4.4 to 4.9 parts per million (p.p.m.) downfield from free 5-fluorouracil. However, the signal from FU59, in the T-loop of tRNA(Val), was shifted more than 1 p.p.m. downfield, to 5.9 p.p.m., presumably because of the involvement of this fluorouracil in the tertiary interactions between the T and D-loops. The 19F chemical shift moved upfield, to the 2.0 to 2.8 p.p.m. range, when fluorouracil was base-paired with adenine in helical stems. This upfield shift was less pronounced for the fluorine of the FU7.A66 base-pair, located at the base of the acceptor stem, an indication that FU7 is only partially stacked on the adjacent G49 in the continuous acceptor stem/T-stem helix. An unanticipated finding was that the 19F resonances of 5-fluorouracil residues wobble base-paired with guanine were shifted 4 to 5 p.p.m. downfield of those from fluorouracil residues paired with A. In the 19F NMR spectra of all fluorinated tRNAs studied, the farthest downfield peak corresponded to FU55, which replaced the conserved pseudouridine normally found at this position.

Fluorine-19 nuclear magnetic resonance as a probe of the solution structure of mutants of 5-fluorouracil-substituted Escherichia coli valine tRNA

In order to utilize 19F nuclear magnetic resonance (NMR) to probe the solution structure of Escherichia coli tRNAVal labeled by incorporation of 5-fluorouracil, we have assigned its 19F spectrum. We describe here assignments made by examining the spectra of a series of tRNAVal mutants with nucleotide substitutions for individual 5-fluorouracil residues. The result of base replacements on the structure and function of the tRNA are also characterized. Mutants were prepared by oligonucleotide-directed mutagenesis of a cloned tRNAVal gene, and the tRNAs transcribed in vitro by bacteriophage T7 RNA polymerase. By identifying the missing peak in the 19F NMR spectrum of each tRNA variant we were able to assign resonances from fluorouracil residues in loop and stem regions of the tRNA. As a result of the assignment of FU33, FU34 and FU29, temperature-dependent spectral shifts could be attributed to changes in anticodon loop and stem conformation. Observation of a magnesium ion-dependent splitting of the resonance assigned to FU64 suggested that the T-arm of tRNAVal can exist in two conformations in slow exchange on the NMR time scale. Replacement of most 5-fluorouracil residues in loops and stems had little effect on the structure of tRNAVal; few shifts in the 19F NMR spectrum of the mutant tRNAs were noted. However, replacing the FU29.A41 base-pair in the anticodon stem with C29.G41 induced conformational changes in the anticodon loop as well as in the P-10 loop. Effects of nucleotide substitution on aminoacylation were determined by comparing the Vmax and Km values of tRNAVal mutants with those of the wild-type tRNA. Nucleotide substitution at the 3' end of the anticodon (position 36) reduced the aminoacylation efficiency (Vmax/Km) of tRNAVal by three orders of magnitude. Base replacement at the 5' end of the anticodon (position 34) had only a small negative effect on the aminoacylation efficiency. Substitution of the FU29.A41 base-pair increased the Km value 20-fold, while Vmax remained almost unchanged. The FU4.A69 base-pair in the acceptor stem, could readily be replaced with little effect on the aminoacylation efficiency of E. coli tRNAVal, indicating that this base-pair is not an identity element of the tRNA, as suggested by others.

Postsplenectomy leukocystosis: physiologic or an indicator of infection?

The records of 42 patients who underwent splenectomy following blunt abdominal trauma were reviewed to determine whether white blood cell (WBC) count is a useful indicator of acute infection in the postoperative period. Patients, ranging in age from 14 to 54 years, were divided into two groups: 1) infected (n = 18) and 2) noninfected (n = 24). Group average daily WBC counts (thousands/mm3) and differential counts (polymorphonuclear leukocyte/bands) were evaluated for the first 14 postoperative days. The infected group had a mean WBC of 21.2 and a mean differential count of 73/8. The average daily WBC count began to rise on Day 4 (WBC = 10.8) and peaked on Day 7 at 27.8. There were 30 episodes of infection: 14 pneumonias and 16 others, including sinusitis, empyema, subphrenic abscess, urinary tract infection, and bacteremias. The noninfected group had a mean WBC count of 14.2 and a mean differential of 73/5. For this group, the average WBC peaked by the postoperative Day 2 (WBC = 15.9), then the trend was downward. Thus, for patients with traumatic splenic injuries, WBC count may predict infection in the postsplenectomy period. In the noninfected group, the authors observed no average daily WBC count above 16; whereas, in the infected group, no average daily WBC count less than 16 was observed. The differential counts were not significantly different between the two groups.

Polyarthritis associated with hydatid disease (echinococcosis) of the liver

A 36-year-old male developed asymmetric polyarthritis during the course of hydatid disease of the liver. Excision of the hydatid cyst was accompanied by full remission of the arthritis without recurrence during the 7-year follow-up period. This sequence of clinical events suggests an eventual cause and effect relationship. A "reactive" immune mechanism, triggered by a parasite located at a distant site, appears to be responsible for this type of arthritis.

[Echinococcus cyst of the breast imitating carcinoma]

A 3 x 4 cm breast mass in a 38-year-old woman was surgically removed and was found to be an echinococcal cyst; thorough investigation failed to reveal any other hydatid cysts. Echinococcal cyst should be considered in the differential diagnosis of the much more common malignant breast mass.