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Biomedical subjects

G Peters

Publications and source records attributed to G Peters.

At least 253 records · Page 14Linked to original sources
PubMed1988

Simultaneous therapy with high-dose cisplatin and radiation for unresectable squamous cell cancer of the head and neck: a phase I-II study.

Studies using simultaneous radiation therapy and conventional doses of cisplatin have suggested improvement in local control and patient survival. This study was undertaken to determine toxicity and patient tolerance to concomitant high-dose cisplatin (40 mg/m2 per day X 5) and radiation (60 Gy in 6 wk +/- 10-Gy boost to residual tumor). Seventeen patients with advanced, inoperable squamous cell cancer primary tumor in the head and neck were treated (15 males and 2 females; median age, 57 yr). Cisplatin was started on day 1 of radiation therapy and repeated every 28 days for three cycles. Normal saline infusion (250 ml/hr) was started 12 hours prior to the first dose and continued 12 hours after the fifth dose. The daily dose of cisplatin was dissolved in 250 ml of 3% NaCl and given over 30 minutes. The cisplatin dose for subsequent cycles was reduced 10 mg/m2 per day only for a nadir granulocyte count less than 500/mm3 or fever greater than 101 degrees F during leukopenia. Of the 17 patients who started therapy, 15 have completed therapy; 1 patient died after one cycle, and 1 died after two cycles. Eleven patients received three cycles of cisplatin, and 10 patients required one dose reduction (6 at course 2 and 4 at course 3). Seven possible infections were successfully treated. Grade 2 neuropathy occurred in 3 patients, and renal toxicity greater than grade 1 occurred in 1 patient. Additional toxic effects were median WBC count nadir of 1.8 X 10(3)/mm3, platelet count nadir of 128 X 10(3)/mm3, hemoglobin nadir of 9.8 g/dl, and median weight loss of 5%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Injection of noradrenaline into the hypothalamic paraventricular nucleus produces vigorous gnawing in satiated rats.

Single injections of noradrenaline (NA) into the hypothalamic paraventricular nucleus (PVN) initiate short bouts of eating in the rat. The effect of the injections of NA (40 nM) into the PVN on gnawing was studied in satiated male rats that had displayed a reliable eating response to NA. The NA injections produced numerous bouts of prolonged and vigorous gnawing of wood pieces shaped like food pellets. The gnawing response started 0.5-2 min after the injection of NA and lasted for 20-25 min. The results suggest that the increase in gnawing and eating evoked by NA might be related to facilitation of the oral responses, and a changed sensitivity to the food related stimuli, in addition to an intrinsic increase in appetite.

Animals↗
PubMed1987

Complete nucleotide sequence of a milk-transmitted mouse mammary tumor virus: two frameshift suppression events are required for translation of gag and pol.

We sequenced two recombinant DNA clones constituting a single provirus of the milk-transmitted mouse mammary tumor virus characteristic of BR6 mice. The complete provirus is 9,901 base pairs long, flanked by 6 base-pair duplications of cellular DNA at the site of integration. Five extensive blocks of open reading frame corresponding to the gag gene, the presumed protease, the pol and env genes, and the open reading frame orf within the long terminal repeat of the provirus were readily discernible. Translation of gag, protease, and pol involved three different translational reading frames to produce the three overlapping polyprotein precursors Pr77, Pr110, and Pr160 found in virus-infected cells. Synthesis of the reverse transcriptase and endonuclease therefore required two separate frameshifts to suppress the termination codons at the ends of the Pr77 and Pr110 domains. Direct evidence is presented for translational readthrough of both stop codons in an in vitro protein synthesis system.

Amino Acid Sequence↗
PubMed1987

Alpha-coma: clinical and evoked potential studies.

Simultaneous brainstem auditory and somatosensory evoked potential studies to median nerve stimulation were performed in two comatose patients, having diffuse alpha-pattern in their EEGs. CT scan of the brain in both cases did not reveal any mass lesion. In Case 1, the clinical and evoked potential studies suggested a brain stem lesion, and in Case 2 there was diffuse encephalopathy, with asymmetric dysfunction of the brainstem as seen in the evoked potential patterns. The suggested separation of alpha-pattern into two distinct groups, based on the reactivity and the presence or absence of sleep activities, into brainstem and diffuse cortical lesions could not be supported by our evoked potential studies. Our study, based on the observations of the evoked potential studies, indicated that the reactivity to sensory stimulation and intermittent attenuation of diffuse alpha-like activity relate to the integrity of the ascending sensory inputs to the thalamus. In the absence of evoked potential data, the localization of lesion(s) in alpha-coma pattern may be imprecise. Moreover, the circadian sleep rhythms and the presence or absence of "sleep spindles" appeared to depend on the inputs of the ascending sensory pathways to the structures generating the sleep activities. The specific neuronal structures generating the alpha-pattern still remain unidentified; however, this pattern seems to be originating from the structures rostral to the mesencephalon, possibly in the thalamic-thalamocortical circuits.

Adult↗
PubMed1986

Insertion elements and transitions in cloned mouse mammary tumour virus DNA: further delineation of the poison sequences.

The provirus of mouse mammary tumour virus (MMTV) is reputed to contain sequences within the viral gag gene that prevent or inhibit its propagation as a recombinant DNA clone in Escherichia coli. Here we report the successful isolation of several lambda and plasmid clones comprising the 5' virus-host DNA junction fragments from integrated MMTV proviruses in BR6 mice. Although the lambda clones appeared intact, almost all of the plasmids were found to contain the bacterial insertion sequences IS1 or IS2 within a small region of the gag gene. One nondisrupted clone was recovered which had undergone multiple G to A transitions, some of which created stop codons in gag. These results have provided more precise information as to the location of the poison sequences and are discussed in relation to possible explanations for the phenomenon.

Amino Acid Sequence↗
PubMed1986

Sequence, topography and protein coding potential of mouse int-2: a putative oncogene activated by mouse mammary tumour virus.

A major proportion of carcinomas induced by mouse mammary tumour virus (MMTV) show evidence for proviral activation of a cellular gene, int-2, on chromosome 7. The sequence of 7869 bp of DNA spanning the transcription unit of int-2 was determined and compared with that of a series of int-2-specific cDNA clones derived from mammary tumour RNA. The predicted positions of intron-exon boundaries, established by alignment of cDNA and chromosomal DNA sequences, indicate that the gene comprises at least three exons. An open reading frame capable of encoding a protein of 245 amino acids with an estimated mol. wt of 27 kd, is flanked by substantial non-coding segments at both 5' and 3' ends. Comparison of the chromosomal DNA sequence and the predicted amino acid sequence with available data-bases has revealed no homology to other known genes. These results are discussed in relation to the status of int-2 as a candidate proto-oncogene.

Amino Acid Sequence↗
PubMed1986

Investigations on ofloxacin: antibacterial activity and influence on the immune system.

The in vitro activity of ofloxacin was tested against freshly isolated strains, from clinical material, of Pseudomonas aeruginosa, Staphylococcus aureus, and coagulase-negative staphylococci, including strains that were resistant to methicillin and/or novobiocin. 97% of the Pseudomonas strains were inhibited by ofloxacin concentrations in the range of 0.78 to 6.25 mg/l, with 55% of the strains being inhibited by concentrations up to 1.56 mg/l. All of the staphylococci strains, including those resistant to novobiocin and/or methicillin, were sensitive to ofloxacin in the range 0.19 to 1.56 mg/l. The influence of ofloxacin on cellular and humoral host immunity was evaluated both in vivo and in vitro. The influence of the compound on phagocytic activity of human polymorphonuclear leucocytes was evaluated by luminol-enhanced chemiluminescence. Ofloxacin did not influence cell-mediated immunity. It had no effect on chemotaxis. The use of sub-inhibitory concentrations of ofloxacin enhanced the phagocytic kill rate.

Animals↗
PubMed1986

Treatment of nonunited scaphoid fractures by pulsed electromagnetic field and cast.

Thirty-five of 44 nonunited scaphoid fractures that were at least 6 months old healed in a mean time of 4.3 months during pulsed electromagnetic field (PEMF) treatment using external coils and a thumb spica cast. The mean time from the onset of the fracture to treatment was 40 months. No concurrent operation was performed. Follow-up time averaged 8.4 months. Eight of nine fractures with avascular necrosis healed. Five of eight fractures in the proximal third healed. Twelve (75%) of 16 patients treated in short-arm thumb spica casts and PEMF healed versus 22 (92%) of 24 patients treated initially in long-arm thumb spica casts and PEMF. We have found PEMF to be a reliable alternative method of treating nonunited scaphoid fractures. Because of the low risk, simplicity of use, and reliability, we recommend its consideration in the treatment of undisplaced, nonunited fractures without carpal instability less than 5 years after the injury. Treatment should initially begin with a long-arm cast.

Adolescent↗
PubMed1986

In-vitro activity of ticarcillin with and without clavulanic acid against clinical isolates of gram-positive and gram-negative bacteria.

The in-vitro activity of ticarcillin with and without clavulanic acid was investigated against 285 freshly isolated clinical strains of Gram-positive and Gram-negative bacteria by the agar-dilution technique on Mueller-Hinton-agar. Clavulanic acid had an excellent or moderate potentiating effect on the in-vitro activity of ticarcillin against staphylococci, Escherichia coli, Klebsiella spp., Enterobacter aerogenes, Proteus mirabilis, Citrobacter spp., Acinetobacter, Haemophilus influenzae and Bacteroides spp. No effect was seen against enterococci, indole-positive Proteus spp., Ent. cloacae, Serratia marcescens and Pseudomonas aeruginosa. The effect of clavulanic acid was dose- and inoculum-dependent.

Bacterial Infections↗
PubMed1986

Interference with granulocyte function by Staphylococcus epidermidis slime.

The interaction of Staphylococcus epidermidis slime with human neutrophils (PMN) was examined by using isolated slime and allowing bacteria to elaborate slime and other extracellular products in situ. S. epidermidis slime was found to contain a chemoattractant. Incubation of PMN with 50 micrograms or more of slime per ml inhibited subsequent chemotaxis of the PMN to n-formyl-methionyl-leucyl-phenylalanine by 27% and to zymosan-activated serum by 44 to 67% with increasing slime concentrations. S. epidermidis slime stimulated little degranulation of untreated PMN. After pretreatment of PMN with 5 micrograms of cytochalasin b per ml, slime predominantly induced release of specific granule contents (33.8% lactoferrin release by 250 micrograms of slime per ml versus 10% myeloperoxidase release by 250 micrograms of slime per ml). By a surface phagocytosis assay, PMN uptake of radiolabeled S. epidermidis which were incubated for 18 h on a plastic surface for slime expression was less than that for S. epidermidis adhered to the plastic for 2 h or grown in unsupplemented nutrient broth. These results suggest that S. epidermidis slime interaction with PMN may be potentially detrimental to host defense and may contribute to the ability of this organism to persist on surfaces of foreign bodies in the vascular or central nervous system.

Chemotaxis, Leukocyte↗
PubMed1986

Characterization, chromosome assignment, and segregation analysis of endogenous proviral units of mouse mammary tumor virus.

In the course of analyzing sites of proviral integration in tumors induced by mouse mammary tumor virus (MMTV), we have isolated recombinant DNA clones corresponding to the 5' and 3' ends of four endogenous MMTV proviruses present in BALB/c and BR6 mice. This has permitted the structural characterization of each locus by detailed restriction mapping and the preparation of DNA probes specific for the cellular sequences flanking each provirus. These probes have been used to trace the segregation patterns of the proviruses, designated Mtv-8, Mtv-9, Mtv-17, and Mtv-21, in a panel of inbred strains of laboratory mice and to map Mtv-17 and Mtv-21 to mouse chromosomes 4 and 8, respectively. The unambiguous resolution of these four proviruses on Southern blots has greatly facilitated the analysis of other endogenous MMTV proviruses in these inbred mice.

Animals↗
PubMed1986

Characterization and chromosome assignment of the human homolog of int-2, a potential proto-oncogene.

int-2 is one of two cellular genes (int-1 and int-2) currently implicated in the genesis of mammary carcinomas by mouse mammary tumor virus and may constitute a novel cellular proto-oncogene. Using low-stringency hybridization with mouse int-2 probes, we established that homologous genes exist in a variety of mammalian species, including humans, but failed to detect related sequences in other classes and phyla. Recombinant bacteriophage clones and a single cosmid encompassing the human int-2 gene were isolated and characterized by restriction enzyme mapping. A survey of nine primary human breast tumors, three breast tumor cell lines, and three normal individuals revealed no evidence for gross amplification or rearrangement of the int-2 locus. Three distinct restriction fragment length polymorphisms were observed which could prove useful in future linkage studies. By a combination of in situ hybridization of metaphase chromosomes and somatic cell genetics, the human int-2 gene was mapped to chromosome 11, band q13.

Animals↗
PubMed1986

[Infections caused by coagulase-negative Staphylococci in immunocompromised patients].

Coagulase-negative staphylococci are important members of the normal aerobic microflora of human skin and mucous membranes. Normally they are not pathogenic for men. But the increase in patients with implanted plastic foreign bodies or intravascular catheters had led to a dramatic change. In these patients, coagulase-negative staphylococci are the predominant organisms causing septicemia. Special pathomechanisms are involved in the colonization of polymers by staphylococci leading to a "plastic infection". Intravascular catheters are also important factors in the origin of septicemia in premature neonates and in patients with malignant diseases, especially under cytostatic therapy. Premature or suppressed opsonophagocytosis mechanisms are responsible for the origin and maintainance of septicemia.

Antineoplastic Agents↗