PubMed Health⌕ Search

Biomedical subjects

L Bertsch

Publications and source records attributed to L Bertsch.

8 recordsLinked to original sources
PubMed1993

Guanosine pentaphosphate phosphohydrolase of Escherichia coli is a long-chain exopolyphosphatase.

An exopolyphosphatase [exopoly(P)ase; EC 3.6.1.11] activity has recently been purified to homogeneity from a mutant strain of Escherichia coli which lacks the principal exopoly(P)ase. The second exopoly(P)ase has now been identified as guanosine pentaphosphate phosphohydrolase (GPP; EC 3.6.1.40) by three lines of evidence: (i) the sequences of five tryptic digestion fragments of the purified protein are found in the translated gppA gene, (ii) the size of the protein (100 kDa) agrees with published values for GPP, and (iii) the ratio of exopoly(P)ase activity to GPP activity remains constant throughout a 300-fold purification in the last steps of the procedure. The enzyme liberates orthophosphate by processive hydrolysis of the phosphoanyhydride bonds of polyphosphate [poly(P)] chains (1000 residues) or by hydrolysis of the 5'-gamma-phosphate of guanosine 5'-triphosphate 3'-diphosphate (pppGpp) to guanosine 5'-diphosphate 3'-diphosphate (ppGpp or "magic spot"). The Km for long-chain poly(P) as a substrate (approximately 0.5 nM) is far lower than that for pppGpp (0.13 mM); the kcat for the poly(P)ase activity is 1.1 s-1 and that for pppGpp hydrolase is 0.023 s-1. These and other findings direct attention to possible functions of poly(P) in the response of E. coli to stresses and deprivations.

Amino Acid Sequence↗
PubMed1989

Intracarotid cisplatin chemotherapy for recurrent gliomas.

Forty patients with recurrent gliomas were treated with monthly intra-arterial infusions of cisplatin. Of the 35 evaluable patients, 12 (34%) responded with computerized tomography (CT) evidence of a decrease in tumor size; in 14 (40%) the tumor stabilized on CT scans, and in nine (26%) the disease progressed. The median survival period was 35.0 weeks for the responders and 27.5 weeks for all 35 patients. The primary toxicities were renal (reversible alterations in creatinine clearance), otological (severe hearing loss in one patient), and likely neurotoxicity in one patient who had received bilateral infusions following contralateral tumor progression. The authors are now using this form of regional chemotherapy sequentially before and following radiotherapy in newly diagnosed cases.

Adult↗
PubMed1989

Systemic beta-interferon therapy for recurrent gliomas: a brief report.

Recombinant beta-interferon in escalating dosages was administered intravenously three times weekly to seven patients with recurrent gliomas. No evidence of response was seen in any patient, either on neurological examination or by computerized tomography (CT). However, stabilization of tumor volume, assessed from contrast-enhanced CT scans, occurred for 8 to 26 weeks in three patients. Immediate progression of disease despite treatment occurred in four patients.

Adult↗
PubMed1988

Systemic gamma-interferon therapy for recurrent gliomas.

Recombinant gamma-interferon (2 mg/sq m) was administered intravenously twice weekly in 8-week courses to 14 patients with recurrent gliomas. Computerized tomography (CT) evidence of response was seen in only one patient, and stabilization for 12 to 86 weeks was recorded in three. This was a disappointing result, particularly in a series of patients with relatively small initial tumor volumes (less than 50 cu mm on enhanced CT) and Karnofsky functional ratings of 70 or higher. In addition, several instances of toxicity potentially attributable to gamma-interferon were observed.

Acute Kidney Injury↗
PubMed1987

Randomized phase III trial of single versus multiple chemotherapeutic treatment following surgery and during radiotherapy for patients with anaplastic gliomas.

In 81 patients with anaplastic supratentorial gliomas, single versus multiple chemotherapeutic agents were selected for treatment following surgery and during radiotherapy in a prospective randomized study. Time to treatment failure and survival were not significantly enhanced by multiple agent chemotherapy, as administered in this study.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1986

Central neurotoxicity following intracarotid BCNU chemotherapy for malignant gliomas.

Central neurotoxicity is reported in 5 of 16 patients with recently diagnosed anaplastic gliomas, who received intra-arterial BCNU (200 mg/M2/course) and also 2 in a series of 26 patients with recurrent gliomas similarly treated. Neurotoxicity was usually delayed, commencing several weeks following the second or third course. CT scans during central neurotoxicity represented 1 or more of 3 patterns: no change; increased low density area(s); and/or ipsilateral gyral enhancement and punctate calcification in the middle cerebral artery territory. In one clinicopathological correlation, coagulative necrosis of the white matter was observed, identical histologically to those changes recognized as delayed vascular events following radiotherapy. Cautious exploration of the various clinical factors that may contribute to this toxicity seems appropriate, as exploration of the potential benefits of regional chemotherapeutic infusions is undertaken.

Brain Neoplasms↗