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Biomedical subjects

R J Klein

Publications and source records attributed to R J Klein.

At least 19 recordsLinked to original sources
PubMed2001

Computational identification of noncoding RNAs in E. coli by comparative genomics.

Some genes produce noncoding transcripts that function directly as structural, regulatory, or even catalytic RNAs [1, 2]. Unlike protein-coding genes, which can be detected as open reading frames with distinctive statistical biases, noncoding RNA (ncRNA) gene sequences have no obvious inherent statistical biases [3]. Thus, genome sequence analyses reveal novel protein-coding genes, but any novel ncRNA genes remain invisible. Here, we describe a computational comparative genomic screen for ncRNA genes. The key idea is to distinguish conserved RNA secondary structures from a background of other conserved sequences using probabilistic models of expected mutational patterns in pairwise sequence alignments. We report the first whole-genome screen for ncRNA genes done with this method, in which we applied it to the "intergenic" spacers of Escherichia coli using comparative sequence data from four related bacteria. Starting from >23,000 conserved interspecies pairwise alignments, the screen predicted 275 candidate structural RNA loci. A sample of 49 candidate loci was assayed experimentally. At least 11 loci expressed small, apparently noncoding RNA transcripts of unknown function. Our computational approach may be used to discover structural ncRNA genes in any genome for which appropriate comparative genome sequence data are available.

Animals↗
PubMed2000

Locoregional cancer treatment with magnetic drug targeting.

The specific delivery of chemotherapeutic agents to their desired targets with a minimum of systemic side effects is an important, ongoing challenge of chemotherapy. One approach, developed in the past to address this problem, is the i.v. injection of magnetic particles [ferrofluids (FFs)] bound to anticancer agents that are then concentrated in the desired area (e.g., the tumor) by an external magnetic field. In the present study, we treated squamous cell carcinoma in rabbits with FFs bound to mitoxantrone (FF-MTX) that was concentrated with a magnetic field. Experimental VX-2 squamous cell carcinoma was implanted in the median portion of the hind limb of New Zealand White rabbits (n = 26). When the tumor had reached a volume of approximately 3500 mm3, FF-MTX was injected intraarterially (i.a.; femoral artery) or i.v. (ear vein), whereas an external magnetic field was focused on the tumor. FF-MTX i.a. application with the external magnetic field resulted in a significant (P < 0.05), complete, and permanent remission of the squamous cell carcinoma compared with the control group (no treatment) and the i.v. FF-MTX group, with no signs of toxicity. The intratumoral accumulation of FFs was visualized both histologically and by magnetic resonance imaging. Thus, our data show that i.a. application of FF-MTX is successful in treating experimental squamous cell carcinoma. This "magnetic drug targeting" offers a unique opportunity to treat malignant tumors locoregionally without systemic toxicity. Furthermore, it may be possible to use these magnetic particles as a "carrier system" for a variety of anticancer agents, e.g., radionuclides, cancer-specific antibodies, and genes.

Animals↗
PubMed1998

Toward a resolution of the introns early/late debate: only phase zero introns are correlated with the structure of ancient proteins.

We present evidence that a well defined subset of intron positions shows a non-random distribution in ancient genes. We analyze a database of ancient conserved regions drawn from GenBank 101 to retest two predictions of the theory that the first genes were constructed by exon shuffling. These predictions are that there should be an excess of symmetric exons (and sets of exons) flanked by introns of the same phase (positions within the codon) and that intron positions in ancient proteins should correlate with the boundaries of compact protein modules. Both these predictions are supported by the data, with considerable statistical force (P values < 0.0001). Intron positions correlate to modules of diameters around 21, 27, and 33 A, and this correlation is due to phase zero introns. We suggest that 30-40% of present day intron positions in ancient genes correspond to phase zero introns originally present in the progenote, while almost all of the remaining intron positions correspond to introns added, or moved, appearing equally in all three intron phases. This proposal provides a resolution for many of the arguments of the introns-early/introns-late debate.

Animals↗
PubMed1992

Health status indicators: definitions and national data.

In July 1991 the Centers for Disease Control (CDC) released a set of 18 health status indicators and encouraged their use by federal, State, and local health agencies. The indicators were developed in response to Objective 22.1 of Healthy People 2000 through a consensus process described in a previous Statistical Notes. This article recommends detailed definitions, suggests national data sources, and provides national baseline data for each indicator.

Centers for Disease Control and Prevention, U.S.↗
PubMed1991

Native herpes simplex virus glycoprotein D vaccine: immunogenicity and protection in animal models.

Mice, guinea pigs, and rhesus monkeys were immunized with immunoaffinity-purified native glycoprotein D (gD) derived from herpes simplex virus type 1 (HSV1). The native glycoprotein has evoked significant in vivo responses even at low doses. Thus, mice immunized with doses as low as 1 microgram were significantly protected from the morbidity and mortality of lethal HSV2 challenge and from establishment of latent HSV2 infection. Protection was dose-related and correlated with prechallenge serum neutralizing antibody titres to HSV. Similarly, immunized guinea-pigs demonstrated significant reductions in the frequency, severity and duration of genital lesions induced by HSV2 vaginal challenge. In long term immunogenicity studies, immunized rhesus monkeys exhibited significant serum neutralizing antibody responses to both HSV1 and HSV2. In vitro stimulation of monkey peripheral blood leucocytes with purified gD resulted in a significant cellular proliferative response. The results obtained in these animal models with a gD subunit vaccine provide an appropriate foundation for the initiation of human studies.

Animals↗
PubMed1989

Reinfections and site-specific immunity in herpes simplex virus infections.

Studies with human volunteers and patients suffering from recurrent herpes simplex virus (HSV) infections have shown that reinfections with autologous or heterologous strains, occurring at sites distant from those of the recurrences, are possible in a variable proportion of the subjects. Experiments in animals have shown that mice surviving a primary HSV infection in the lumbo-sacral area, can become latently infected in trigeminal ganglia upon reinfection of the orofacial site. Similar results were obtained after vaccination of mice with a thymidine-kinase negative, non-pathogenic HSV-1 mutant. It was also demonstrated that initial HSV-1 eye infection in rabbits prevents superinfection of trigeminal ganglia by other strains.

Animals↗
PubMed1988

Intravenous acyclovir therapy of first episodes of genital herpes: a multicenter double-blind, placebo-controlled trial.

PURPOSE: A collaborative multicenter double-blind, placebo-controlled trial of intravenous acyclovir treatment of first-episode genital herpes was performed in order to substantiate previous findings on the efficacy and safety of this drug, to evaluate the influence of parenteral therapy on recurrence frequency, and to obtain further data on the natural history of genital herpes. PATIENTS AND METHODS: Eighty-two patients with first episodes of genital herpes simplex virus (HSV) infection were randomly assigned in a double-blind fashion to treatment with intravenous acyclovir (5 mg/kg every eight hours) or placebo for five days. Before therapy, all lesions in the genital/perineal area and in extragenital sites were cultured. New lesions appearing in both areas after the onset of therapy were cultured separately. Lesions in all groups were cultured until completely healed. Sera were collected from all patients on entry to the study and on Day 21 to determine presence or absence of antibodies to HSV-1 and HSV-2. Time to healing, time to crusting, time to cessation of viral shedding, and appearance of new lesions during therapy were compared for each treatment group. RESULTS: Patients receiving acyclovir experienced a significant reduction in the median duration of pain (4.3 versus 4.8 days, p = 0.019), viral shedding (1.9 versus 8.4 days, p less than 0.001), and time to healing (8.4 versus 11.5 days, p = 0.02) compared with placebo recipients. These differences were largely attributable to the effect of therapy in the subset of patients with primary disease in whom acyclovir reduced the median duration of pain from 10.6 days to 4.2 days, the median duration of viral shedding from 17.1 days to 1.9 days, and the median time to healing from 14.2 days to 8.3 days. The rate of subsequent recurrence of genital herpes was not altered by acyclovir treatment: 24 of 32 acyclovir recipients (75 percent) experienced one or more recurrences during a mean follow-up of 14 months compared with 19 of 27 placebo recipients (70 percent). Among patients experiencing recurrences, the mean number of recurrences per month among acyclovir recipients was 0.25 compared with 0.19 for patients given placebo. CONCLUSION: This multicenter trial confirms the efficacy of intravenous acyclovir in the management of first-episode genital herpes, especially in patients with primary infection. However, therapy did not alter the frequency of recurrences.

Acyclovir↗
PubMed1987

Spread of herpes simplex virus in lymph nodes after experimental infection of mice.

Herpes simplex virus was frequently isolated from ipsilateral popliteal lymph nodes after percutaneous inoculation of the dorsal face of the footpad, and from ipsi- and contralateral submandibular lymph nodes after percutaneous inoculation of the cheek or the orofacial area of mice. Virus was detected only on very rare occasion in nondraining lymph nodes (inguinal or axillary) or in contralateral popliteal lymph nodes, but was frequently isolated in contralateral lumbar lymph nodes after footpad inoculation. The presence of virus in lymph nodes paralleled or followed the invasion of ipsilateral sensory ganglia and was associated with dissemination of virus in contralateral sensory ganglia after unilateral inoculation. In older mice virus was detected only occasionally in lymph nodes and dissemination of virus in contralateral sensory ganglia was generally not observed. The results suggest that lymphatic spread may contribute to dissemination of virus in contralateral sensory ganglia after unilateral inoculation of mice.

Age Factors↗
PubMed1986

Treatment of recurrent genital herpes with topical alpha interferon gel combined with nonoxynol 9.

A double-blind, placebo-controlled study was done to evaluate the efficacy of an alpha interferon preparation in 128 patients with recurrent genital herpes. The preparation containing 10(5) or 10(7) U alpha interferon with nonoxynol 9 in a cream base (Exovir-HZ) was applied three times daily for 5 days. The treatment did not cause any adverse reactions. Patients treated with either interferon concentration became negative for viral culture at a faster rate than placebo recipients. The end of new lesion formation, scabbing, and the healing of lesions were all superior in patients treated with 10(5) U to those treated with 10(7) U interferon. End of new lesion formation and scabbing were also statistically different in patients treated with 10(7) U from those patients treated with placebo. Results suggest that topical interferon might be useful in relieving symptoms of severe cases of genital herpes.

Administration, Topical↗