Painless neutropenic enterocolitis in a patient undergoing chemotherapy.

CASE DESCRIPTION: A 60-year-old man developed painless neutropenic enterocolitis after induction chemotherapy for newly diagnosed acute myelogenous leukemia. The patient had recurrent fever while neutropenic, without experiencing abdominal pain or tenderness on physical examination. His diagnosis was delayed by the fact that he had no localizing symptoms. DISCUSSION: Neutropenic enterocolitis is a common complication, generally occurring in patients who are severely neutropenic; the condition presents with fever and abdominal pain. No cases of painless neutropenic enterocolitis have yet been reported. Review of the literature shows that patients can develop this condition in the absence of fever and, sometimes, neutropenia. Furthermore, few comprehensive studies or reviews have investigated the utility of computed tomography imaging in identifying a source for abdominal pain in neutropenic patients with fever. SUMMARY: Many potential causes of febrile neutropenia should be considered in chemotherapy patients.

Wet smear compared with gram stain diagnosis of bacterial vaginosis in asymptomatic pregnant women.

OBJECTIVE: To compare wet smear and Gram stain diagnoses of bacterial vaginosis among asymptomatic pregnant women. METHODS: Between November 1, 1996 and December 31, 1997, asymptomatic women who initiated prenatal care in our obstetric clinics were invited to participate. Exclusion criteria included antimicrobial use within 2 weeks, cervical cerclage, vaginal bleeding, placenta previa, spermicide use, douching, or intercourse within 8 hours. Clinical diagnosis that required two of three positive criteria for bacterial vaginosis (vaginal pH, whiff test, and clue cells on wet smear) was compared with Gram stain diagnosis (Bacterial vaginosis score 7-10 by Nugent criteria). RESULTS: Population characteristics (n = 69) included an average (+/- standard deviation [SD]) maternal age of 27. 3 +/- 6.6 years, 26 nulliparas (38%), 28 black women (41%), 23 white women (38%), 15 Hispanic women (22%), and three Asian women (4%). The mean (+/-SD) gestational age at entry was 15.6 +/- 7.6 weeks. Twenty-seven percent (18 of 67) of the study population was diagnosed with bacterial vaginosis by definitive Gram stain. Two slides were lost or were of poor quality and not included. Using Gram stain diagnosis of bacterial vaginosis as the standard, clinical diagnosis had sensitivity of 56% (95% confidence interval [CI] 32%, 78%), a specificity of 96% (95% CI 90%, 100%), a positive predictive value of 83%, and a negative predictive value of 85%. CONCLUSION: In asymptomatic pregnant women, bacterial vaginosis can be diagnosed reliably by Gram stain.

13C labeling indicates that the epoxide-containing amino acid of HC-toxin is biosynthesized by head-to-tail condensation of acetate.

HC-toxin, cyclo(D-Pro-L-Ala-D-Ala-L-Aeo), where Aeo stands for 2-amino-9,10-epoxi-8-oxodecanoic acid, is a potent inhibitor of histone deacetylase. Previous molecular genetic studies indicated that HC-toxin biosynthesis requires a dedicated fatty acid synthase. The incorporation of [13C]acetate into HC-toxin was studied using NMR. The pattern of incorporation of 13C was consistent with the carbons of Aeo being derived from head-to-tail condensation of acetate.

Microbiologic assessment of the transabdominal ultrasound transducer head.

The objectives of this study were to determine (1) the rate of bacterial isolation from the abdomen of women having obstetric ultrasonography, (2) the rate of bacterial transmission to the transducer head, and (3) the eradication rate after routine wiping of the transducer head. A total of 191 obstetric patients participated in this study. At the start of each day, the transducer head and the coupling gel were cultured. Aerobic cultures were obtained from each patient's periumbilical and suprapubic areas before the transabdominal scan and from the transducer head before and after wiping off the gel with a dry cloth. Daily transducer head and gel cultures were negative. Of the abdominal skin cultures, 175 (92%) were positive; 35 (18%) were positive for serious organisms, and 140 (74%) were positive for organisms of low virulence. Sixty percent of the transducer head cultures from women with abdominal skin pathogens were positive before the gel was wiped off. None of the cultures from the transducer head were positive after removal of the gel. We conclude that many women carry potentially virulent pathogens on the abdominal skin and that transmission of these organisms to the transducer head commonly occurs. Physical removal of the gel from the transducer head effectively eradicates these microorganisms, minimizing patient-to-patient transmission.

Improved proton assignment for DNA by application of aliasing and dispersive-absorptive phasing to two-quantum COSY spectra.

A unique combination of aliasing and dispersive-absorptive (DA) phasing of two-quantum correlated spectroscopy (2 Q-COSY) NMR data is shown to enhance proton chemical-shift assignments in DNA oligonucleotides by (i) reducing the time necessary for acquiring NMR data or, alternatively, improving the spectral resolution in a given time, (ii) reducing the number of spectra necessary for NMR data processing and analysis, and (iii) increasing the complexity of oligonucleotide sequences and structures which are accessible to 2D NMR analysis. Aliasing allows a reduction in the size of the acquired data without significant risk of losing information. Phasing the 2Q-COSY dispersive in the F2 dimension reduces the primary antiphase doublet into a pseudo-singlet and increases the apparent signal-to-noise. A single 2Q-COSY spectrum can provide an amount of chemical-shift information comparable to that from a series of COSY, relayed-COSY, and/or spin-lock COSY spectra optimized for various coupling constants. The low signal-to-noise inherent in the most popular two-quantum-filtered correlated spectroscopy (2QF-COSY) of samples with naturally broad lines is largely avoided due to less cancellation. There is no diagonal in a 2Q-COSY which can obscure correlations between protons which are nearly isochronous. As an example of this efficient application, the assignment of 139 of the 143 proton resonances from a single 2Q-COSY and a 2D-NOE spectrum of the DNA hexadecamer [d(AAATATAGCTATATTT)]2 is demonstrated.

Tertiary base pair interactions in slipped loop-DNA: an NMR and model building study.

Short direct repeat sequences are often found in regulatory regions of various genes; in some cases they display hypersensitivity to S1 nuclease cleavage in supercoiled plasmids. A non-standard DNA structure (Slipped Loop Structure, or SLS) has been proposed for these regions in order to explain the S1 cleavage data; the formation of this structure may be involved in the regulation of transcription. The structure can be generally classified as a particular type of pseudoknot. To date, no detailed stereochemical model has been developed. We have applied one-dimensional 1H NMR spectroscopy to study a synthetic DNA, 55 nucleotides in length, which cannot fold as a standard hairpin but which may favor the SLS formation. AT base pairs were identified, consistent only with the formation of an additional, tertiary miniduplex in the SLS. An all-atom stereochemically sound model has been developed for the SLS with the use of conformational calculations. The model building studies have demonstrated that the tertiary miniduplex can be formed for one of the plausible SLS isomers, but not for the other.

Hepatitis B virus direct repeat sequence: imino proton exchange rates and distance and torsion angle restraints from NMR.

Structural features of a trisdecamer duplex, [d(GGCAGAGGTGAAA).d(TTTCACCTCTGCC)], in solution are being investigated by proton one-dimensional (1D) and two-dimensional (2D) NMR spectroscopy. This DNA sequence is comprised of the 11-base-pair direct repeat sequence found in the hepatitis B viral genome with an additional base pair from the genome included on each end to minimize end effects on the 11-bp sequence of interest. The direct repeat sequence occurs twice in the viral genome; both are essential for initiation of DNA synthesis. The critical nature of this sequence suggests it may be a target to control replication of the virus. Elucidation of the structure of the direct repeat sequence could prove to be beneficial in targeting efforts. Structural determination via restrained molecular dynamics requires experimentally derived distance restraints. The ability to determine solution structures of biomolecules by NMR spectroscopy is limited by the quality and quantity of distance and torsion angle restraints that can be extracted from the NMR data. Techniques used to establish these restraints are constantly evolving and improving. Modifications in procedure are applied to the trisdecamer duplex to yield improvements in the determination of sugar conformations from COSY data and a substantial increase in the number of distance restraints typically garnered from 2D NOE intensity data. This increase in the number of distance restraints normally obtained from 2D NOE intensities was accomplished by utilizing a new version of the iterative complete relaxation matrix program MARDIGRAS with intensities extracted from a 2D NOE data set acquired in 90% H2O. The exchange rate of the imino and amino protons with the solvent water protons can now be included in the relaxation matrix calculations, thereby providing more accurate distances when utilizing the 2D NOE cross-peaks involving at least one exchangeable proton. In this lab, analysis of two-quantum-filtered correlation (2QF-COSY) spectra to determine the conformational states of the sugar moieties typically employs the program package SPHINX/LINSHA to simulate the scalar coupling effects manifest in the cross-peaks. With enough data, we typically find that a single conformer is inadequate to describe sugar pucker, but a rapid two-state equilibrium is consistent with all the data. In the process, a large number of cross-peaks are simulated with a range of possible sugar conformation ratios, amplitudes, and line widths. A limitation of this procedure is the possibility of producing a nonunique solution. These methods rely on the ability to match the appearance of simulated cross-peaks with real data.(ABSTRACT TRUNCATED AT 400 WORDS)

Pregnancy outcome in Swiss-Webster mice infected with Chlamydia trachomatis.

OBJECTIVE: The objective of this study was to observe pregnancy outcomes in mice infected transvaginally with Chlamydia trachomatis. METHODS: Pregnant mice were inoculated transvaginally with either C. trachomatis (CT) or sterile calf serum (CON) on pregnancy day 4. Pregnancy outcomes as well as genital tract histology and culture were compared. Statistical analysis was performed using Fisher's exact test and Student's t-test. RESULTS: Twenty-four of 26 CT mice had positive uterine cultures for C. trachomatis. Inflammation occurred in 9 (34.6%) (P = 0.002, 95% confidence interval = 1.7-3.5) and intrauterine fetal demise occurred in 5 (19.2%) (P = 0.05, 95% confidence interval = 1.6-2.9) of CT mice. No mice in the CON group (0/24) had positive uterine cultures, developed inflammation, or experienced intrauterine fetal demise. CONCLUSIONS: Lower genital tract chlamydial infection is associated with intrauterine fetal demise in Swiss-Webster mice.

Actinomycin D induced DNase I hypersensitivity and asymmetric structure transmission in a DNA hexadecamer.

DNase I cleavage rates and nmr chemical shifts are shown to change for DNA sequences distal to an intercalated actinomycin D molecule in a duplex hexadecamer upon drug binding. Both sets of observations suggest that the source of these changes is a DNA-mediated structural response. The nmr results imply the response is transmitted preferentially in a 5'-to-3' direction from the drug binding site. An inequivalent response of the two strands to a ligand-induced conformational change immediately suggests a mechanism for distinguishing the sense and antisense strands of DNA.