Biomedical subjects

C Herman

Publications and source records attributed to C Herman.

At least 19 recordsLinked to original sources

PubMed1998

Degradation of carboxy-terminal-tagged cytoplasmic proteins by the Escherichia coli protease HflB (FtsH).

Proteins with short nonpolar carboxyl termini are unstable in Escherichia coli. This proteolytic pathway is used to dispose of polypeptides synthesized from truncated mRNA molecules. Such proteins are tagged with an 11-amino-acid nonpolar destabilizing tail via a mechanism involving the 10Sa (SsrA) stable RNA and then degraded. We show here that the ATP-dependent zinc protease HflB (FtsH) is involved in the degradation of four unstable derivatives of the amino-terminal domain of the lambdacI repressor: three with nonpolar pentapeptide tails (cI104, cI105, cI108) and one with the SsrA tag (cI-SsrA). cI105 and cI-SsrA are also degraded by the ClpP-dependent proteases. Loss of ClpP can be compensated for by overproducing HflB. In an in vitro system, cI108 and cI-SsrA are degraded by HflB in an energy-dependent reaction, indicating that HflB itself recognizes the carboxyl terminus. These results establish a tail-specific pathway for removing abnormal cytoplasmic proteins via the HflB and Clp proteases.

ATP-Dependent Proteases↗

PubMed1998

Mutation of proline 211 reduces shedding of the human p75 TNF receptor.

We have identified a residue necessary for the cleavage of human p75 TNF-R from the cell surface by deletion and mutagenesis analysis of the membrane-proximal domain between amino acids 147 and 221. Deletion analysis of this area showed that residues between amino acids 207 and 216 are required for shedding. Site-directed mutagenesis of proline 211 to glycine reduced PMA-induced shedding of human p75 TNF-R from COS-7 or Raw 264.7 cells. Mutation of glycine 210 to aspartic acid did not affect receptor shedding. Mutation of serine 212 to leucine did not affect the PMA-induced shedding from the surface of COS-7 cells, but reduced the efficiency of shedding from the surface of Raw 264.7 macrophages by PMA or LPS. Deletion of putative elastase cleavage sites at amino acids 151 to 153, 162 to 163, and 177 to 178 (also a putative metalloprotease site similar to the cleavage site of TNF-alpha) or mutation of a serine-threonine-serine motif resembling a similar motif at the site of L-selectin cleavage at amino acids 202 to 204 did not reduce shedding of p75 TNF-R after treatment of cells with PMA. This work shows that a single amino acid mutation at proline 211 of human p75 TNF-R can prevent shedding from the cell surface, and that deletion of other previously proposed putative cleavage sites of the human p75 TNF-R does not prevent its shedding.

Amino Acid Sequence↗

PubMed1998

Characteristics of rectal carcinomas that predict the presence of lymph node metastases: implications for patient selection for local therapy.

BACKGROUND AND OBJECTIVES: It has been estimated that approximately 5% of middle and low rectal adenocarcinomas are amenable to local therapy. However, these treatment modalities are limited by their failure to identify and treat regional nodal metastases. METHODS: This study was undertaken to evaluate the role of tumor size, depth of penetration into the rectal wall, degree of histologic differentiation, DNA ploidy status, and their combination on the presence or absence of metastases in perirectal lymph nodes. Logistic regression was used to quantitatively predict the probability of positive lymph nodes. RESULTS: Tumor size did not correlate with the presence of nodal involvement; however, worsening degree of differentiation, increasing depth of wall penetration and aneuploidy did statistically correlate with the presence of nodal metastases. For any combination of tumor traits, aneuploidy markedly increased the probability of positive lymph nodes over that observed with diploid tumors. CONCLUSIONS: The combination of degree of differentiation, depth of penetration, and ploidy status may be used to identify patients whose tumors may be adequately treated with local measures. For any combination of tumor traits, aneuploidy markedly increased the probability of positive lymph nodes over that observed with diploid tumors.

Adult↗

PubMed1998

Proteolysis and chaperones: the destruction/reconstruction dilemma.

Cytoplasmic proteases, although necessary for proper cell functioning, must be strictly regulated. In fact, they resemble chaperones, ancient protein folding devices. These molecules recognise exposed hydrophobic regions of unfolded or denatured proteins. For most substances it is not known how the cell chooses between the refolding and proteolytic pathways. In Escherichia coli, however, a carboxy-terminal proteolysis tag and binding site for the chaperone DnaK have recently been identified.

Bacterial Proteins↗

PubMed1998

Gene therapy for rheumatoid arthritis. Theoretical considerations.

Current understanding of the pathogenesis of rheumatoid arthritis has provided evidence that therapeutic benefit can be achieved by using antagonists targeted to the inflammatory cytokines involved, mainly tumour necrosis factor-alpha and interleukin-1. Gene delivery of antagonists, which can inhibit the production or action of these cytokines and other mediators, has been achieved in experimental animal models. This new method of delivery can produce therapeutic effects at lower concentrations and in a local environment, overcoming the adverse effects that often accompany protein therapy. However, several technological and biological restraints preclude the immediate adaptation of this method to human treatment. Based on the experimental evidence, possible target therapeutic genes, cell types and vector systems that could be used are discussed in this article.

Arthritis, Rheumatoid↗

PubMed1997

The HflB protease of Escherichia coli degrades its inhibitor lambda cIII.

The cIII protein of bacteriophage lambda is known to protect two regulatory proteins from degradation by the essential Escherichia coli protease HflB (also known as FtsH), viz., the lambda cII protein and the host heat shock sigma factor sigma32. lambda cIII, itself an unstable protein, is partially stabilized when the HflB concentration is decreased, and its half-life is decreased when HflB is overproduced, strongly suggesting that it is degraded by HflB in vivo. The in vivo degradation of lambda cIII (unlike that of sigma32) does not require the molecular chaperone DnaK. Furthermore, the half-life of lambda cIII is not affected by depletion of the endogenous ATP pool, suggesting that lambda cIII degradation is ATP independent (unlike that of lambda cII and sigma32). The lambda cIII protein, which is predicted to contain a 22-amino-acid amphipathic helix, is associated with the membrane, and nonlethal overproduction of lambda cIII makes cells hypersensitive to the detergent sodium dodecyl sulfate. This could reflect a direct lambda cIII-membrane interaction or an indirect association via the membrane-bound HflB protein, which is known to be involved in the assembly of certain periplasmic and outer membrane proteins.

ATP-Dependent Proteases↗

PubMed1996

Changes in blood cell numbers and formation of eicosanoids during clotting in warm- and cold-acclimated bullfrogs (Rana catesbeiana).

Amphibian blood cells play an important role in eicosanoid synthesis. Formation of eicosanoids during clotting of whole human blood but not frog blood has been reported. Amphibian blood cell numbers are affected by cold exposure; therefore eicosanoid production may reflect these changes. Blood cell changes during warm, and short- and long-term-cold exposure periods were recorded and the formation of leukotriene B4 (LTB4), LTC4, thromboxane (TXB2), and prostaglandin E2 (PGE2) was measured during blood clotting by using radioimmunoassay. Short-term (1 day) cold exposure (5 degrees) did not significantly decrease blood cell number or eicosanoid production during clotting. However, following exposure to cold (5 degrees) for 10 or 30 days, blood cell number and production of LTB4, TXB2, and PGE2 during clotting decreased when compared with warm acclimated controls (22 degrees). LTC4 levels during blood clotting decreased significantly only after 30 days of cold exposure. The results demonstrate that eicosanoid synthesis can be correlated with blood cell number in warm- and cold-exposed bullfrogs.

Acclimatization↗

PubMed1996

Bisallylic hydroxylation and epoxidation of polyunsaturated fatty acids by cytochrome P450.

Polyunsaturated fatty acids can be oxygenated by cytochrome P450 to hydroxy and epoxy fatty acids. Two major classes of hydroxy fatty acids are formed by hydroxylation of the omega-side chain and by hydroxylation of bisallylic methylene carbons. Bisallylic cytochrome P450-hydroxylases transform linoleic acid to 11-hydroxylinoleic acid, arachidonic acid to 13-hydroxyeicosa-5Z,8Z,11Z,14Z-tetraenoic acid, 10-hydroxyeicosa-5Z,8Z,11Z,14Z-tetraenoic acid and 7-hydroxyeicosa-5Z,8Z,11Z,14Z-tetraenoic acid and eicosapentaenoic acid to 16-hydroxyeicosa-5Z,8Z,11Z,14Z,17Z-pent aenoic acid, 13-hydroxyeicosa-5Z,8Z,11Z,14Z,17Z-pent aenoic acid and 10-hydroxyeicosa-5Z,8Z,11Z,14Z,17Z-pent aenoic acid as major metabolites. The bisallylic hydroxy fatty acids are chemically unstable and decompose rapidly to cis-trans conjugated hydroxy fatty acids during acidic extractive isolation. Bisallylic hydroxylase activity appears to be augmented in microsomes induced by the synthetic glucocorticoid dexamethasone and by some other agents, but the P450 gene families of these hydroxylases have yet to be determined. The fatty acid epoxides, which are formed by cytochrome P450, are chemically stable, but are hydrolyzed to diols by soluble epoxide hydrolases. Epoxidation of polyunsaturated fatty acids is a prominent pathway of metabolism in the liver and the renal cortex and epoxy-genase activity appears to be under homeostatic control in the kidney. Many arachidonate epoxygenases have been identified belonging to the CYP2C gene subfamily. Epoxygenases have also been found in the central nervous system, endocrine organs, the heart and endothelial cells. Epoxides of arachidonic acid have been found to exert pharmacological effects on many cells.

Animals↗

PubMed1995

Degradation of sigma 32, the heat shock regulator in Escherichia coli, is governed by HflB.

The heat shock response in Escherichia coli is governed by the concentration of the highly unstable sigma factor sigma 32. The essential protein HflB (FtsH), known to control proteolysis of the phage lambda cII protein, also governs sigma 32 degradation: an HflB-depleted strain accumulated sigma 32 and induced the heat shock response, and the half-life of sigma 32 increased by a factor up to 12 in mutants with reduced HflB function and decreased by a factor of 1.8 in a strain overexpressing HflB. The hflB gene is in the ftsJ-hflB operon, one promoter of which is positively regulated by heat shock and sigma 32. The lambda cIII protein, which stabilizes sigma 32 and lambda cII, appears to inhibit the HflB-governed protease. The E. coli HflB protein controls the stability of two master regulators, lambda cII and sigma 32, responsible for the lysis-lysogeny decision of phage lambda and the heat shock response of the host.

ATP-Dependent Proteases↗

PubMed1995

Regulation of the heat-shock response depends on divalent metal ions in an hflB mutant of Escherichia coli.

HflB, also called FtsH, is an essential Escherichia coli protein involved in the proteolysis of the heat-shock regulator sigma 32 and of the phage regulator lambda cll. The hflB1(Ts) allele (formerly called ftsH1) conferring temperature-sensitive growth at 42 degrees C is suppressed by loss of the ferric-uptake repressor Fur and by anaerobic growth. We show here that suppression requires TonB-dependent Fe(III) transport in the hflB1(Ts) fur mutant during aerobic growth at 42 degrees C and Feo-dependent Fe(II) transport during anaerobic growth at 42 degrees C. Temperature-resistant growth of hflB1(Ts) strains is also observed at 42 degrees C in the presence of a high concentration of Fe(II), Ni(II), Mn(II) or Co(II) salts, but not in the presence of Zn(II), Cd(II), Cu(II), Mg(II), Ca(II) or Cr(III) salts. However, neither Ni(II) nor a fur mutation permits growth in the complete absence of HflB. The heat-shock response, evaluated by an htpG::lacZ fusion, is overinduced in hflB1(Ts) strains at 42 degrees C because of stabilization of sigma 32. Growth in the presence of Ni(II) or in the absence of the Fur repressor abolishes this overinduction in the hflB1(Ts) strain, and, in the hflB1(Ts) fur mutant, sigma 32 is no longer stabilized at 42 degrees C. These results reinforce the recent observation that HflB is a metalloprotease active against sigma 32 in vitro and suggest that it can associate functionally in vivo with Fe(II), Ni(II), Mn(II) and Co(II) ions.

ATP-Dependent Proteases↗

PubMed1995

Leptomeningeal dissemination of malignant glioma simulating cerebral vasculitis. Case report with angiographic and pathological studies.

BACKGROUND: The complex clinical and radiological picture of leptomeningeal spread of tumor is well recognized as a problem of systemic cancer but is less frequent in primary cerebral glioma, particularly as a presenting picture. While brain ischemia and infarction may occur in patients with subarachnoid tumor, the mechanism for these complications remains unclear. Angiographic and pathological demonstrations of direct vascular involvement by disseminated glioma are particularly sparse. We report a patient presenting with multiple infarctlike lesions with postmortem evidence of direct vascular involvement by glioma. CASE DESCRIPTION: A 54-year-old woman presenting with seizures, headache, and changes in mental status was found to have vascular narrowing in cerebral blood vessels and ischemic lesions on neuroimaging studies of the brain, interpreted as cerebral vasculitis. A brain biopsy showed leptomeningeal glioma. Postmortem examination demonstrated a glioblastoma arising around the right sylvian fissure with extensive subarachnoid dissemination of tumor. The leptomeningeal tumor caused vascular narrowing by encasement, direct vascular wall invasion, and thrombosis and was associated with underlying infarctlike foci of parenchymal necrosis. CONCLUSIONS: This case demonstrates an unusual presentation of glioblastoma clinically and radiographically mimicking cerebral vasculitis, and it illustrates a variety of mechanisms for tumor-produced vascular compromise.

Cerebral Angiography↗

PubMed1994

Pseudoepitheliomatous hyperplasia in chronic cutaneous wounds. A flow cytometric study.

Cutaneous squamous cell carcinomas (SCC) arising in a setting of chronic regeneration and repair tend to be highly aggressive lesions prognostically distinct from SCC arising in solar-damaged skin. Full thickness thermal injury and chronic nonhealing ulcers are predisposing conditions in up to 2% of SCC. A significant association has been suggested to exist between pseudoepitheliomatous hyperplasia (PH) and SCC. Three-hundred-eighty-six surgical cases of skin excised secondary to severe burns (n = 254) or chronic ulcers (n = 132) were reviewed, yielding 43 (11%) with PH. Flow cytometric DNA analysis was performed on paraffin-embedded sections. Thirty cases without PH were studied in addition to the 43 cases with PH. The majority (39/43) of the PH cases showed a single diploid population with a mean S-phase of 13.7%. Four cases (9.3%) showed an aneuploid peak. All cases without PH were diploid with a mean S-phase of 9.0%. In this study, PH was present in 11% of cases reviewed, and showed a 50% mean higher S-phase than comparable cases without PH. Aneuploidy was present in 9.3% of the PH cases studied. SCC may arise from a subgroup of PH in a background of rapidly proliferating keratinocytes.

Carcinoma↗

PubMed1993

Cell growth and lambda phage development controlled by the same essential Escherichia coli gene, ftsH/hflB.

The lambda phage choice between lysis and lysogeny is influenced by certain host functions in Escherichia coli. We found that the frequency of lambda lysogenization is markedly increased in the ftsH1 temperature-sensitive mutant. The ftsH gene, previously shown to code for an essential inner membrane protein with putative ATPase activity, is identical to hflB, a gene involved in the stability of the phage cII activator protein. The lysogenic decision controlled by FtsH/HflB is independent of that controlled by the protease HflA. Overproduction of FtsH/HflB suppresses the high frequency of lysogenization in an hflA null mutant. The FtsH/HflB protein, which stimulates cII degradation, may be a component of an HflA-independent proteolytic pathway, or it may act as a chaperone, maintaining cII in a conformation subject to proteolysis via such a pathway. Suppressor mutations of ftsH1 temperature-sensitive lethality, located in the fur gene (coding for the ferric uptake regulator), did not restore FtsH/HflB activity with respect to lambda lysogenization.

ATP-Dependent Proteases↗

PubMed1992

Prognostic significance of DNA ploidy in male breast carcinoma. A retrospective analysis of 32 cases.

BACKGROUND: DNA aneuploidy has been prognostically significant in female breast carcinoma of low stage, but its value in male breast carcinoma remains undetermined. METHODS: Flow cytometric DNA analyses were performed retrospectively on paraffin-embedded tissue from 32 men with breast carcinoma (mean follow-up time, 5.97 years [standard deviation +/- 4.63]; range, 1 to 18 years). RESULTS: Multivariate discriminant function analysis showed only tumor size less than 2 cm to be independently predictive of better disease-free survival (P less than 0.05). DNA ploidy (aneuploid, 25 patients; diploid, 7 patients) and lymph node status (positive, 22 patients; negative, 10 patients) were not predictive of survival, regardless of tumor size. CONCLUSIONS: The authors concluded that DNA ploidy may not significantly predict survival in male breast carcinoma.

Adult↗

PubMed1992

Flow and image cytometric DNA analysis in Ewing's sarcoma.

Ewing's sarcoma is the second most common bone tumor in childhood, with an overall 5-yr survival of 40%. It is one of the poorly differentiated small spherical cell tumors frequently requiring distinction from rhabdomyosarcoma, neuroblastoma, osteosarcoma, primitive neuroectodermal tumor, and lymphoma. The majority of rhabdomyosarcomas, neuroblastomas, and osteosarcomas are aneuploid, whereas Ewing's sarcomas are usually diploid. To determine whether there is any correlation between DNA content, morphology, site, and survival in Ewing's sarcoma and extraosseous Ewing's sarcoma, 21 tumor samples were studied retrospectively (3 extraosseous Ewing's and 18 Ewing's sarcomas). The DNA analysis was performed on disaggregated paraffin-embedded tissue nuclei by flow (FCM) and image (IC) cytometry and correlated with the histology and clinical history. The DNA ploidy by FCM on 17 of 18 Ewing's sarcoma samples was 12 diploid, 1 aneuploid, and 4 tetraploid. By IC, the DNA ploidy on 16 samples was 13 diploid, 1 aneuploid, and 2 tetraploid. Three samples were nonevaluable (1 by FCM and 2 by IC). The agreement between FCM and IC was 12 of 16 (75%). The extraosseous Ewing's sarcoma tumors were 2 diploid and 1 aneuploid by IC. In this study there was no correlation between the DNA ploidy and either the histology, site, or survival.

Adolescent↗

PubMed1991

Corneal ulcer and adverse reaction rates in premarket contact lens studies.

We analyzed clinical data on 22,739 contact lens wearers who were studied and whose lenses were approved under 48 manufacturer-sponsored studies for the Food and Drug Administration between 1980 and 1988. The incidence of corneal ulcers was low in the cosmetic (nontherapeutic) daily-wear soft and rigid gas-permeable lens wearers (1/1,923 and 1/1,471 patient-years, respectively). Corneal ulcers and severe adverse reactions occurred two to four times more frequently in extended-wear cosmetic soft and rigid gas-permeable lens wearers than in cosmetic daily-wear lens wearers. Aphakic extended-wear soft lens users were nine times more likely to develop a corneal ulcer when compared to the soft daily-wear cosmetic group. Corneal abrasions and keratitis accounted for 81 of 159 severe adverse reactions, whereas corneal ulcers accounted for 28 of 159 adverse reactions. The data indicate that overnight extended wear of contact lenses is associated with a greater risk of serious, sight-threatening complications than daily wear.

Aphakia↗

PubMed1990

Flow and image cytometric DNA analysis in rhabdomyosarcoma.

Rhabdomyosarcoma is the most common malignant soft-tissue tumor in childhood, with an overall 3-year disease-free survival of 73%. DNA content is known to correlate with prognosis and therapy response in many cancers. To determine the role of DNA content in rhabdomyosarcoma, 23 tumor samples were studied retrospectively: 18 primary tumors and 5 post-chemotherapy recurrences or specimens obtained at second-look surgeries. The DNA analysis was performed on disaggregated paraffin-embedded tissue nuclei by flow and image cytometry and correlated with the histology and clinical history. Of the primary tumors 4 were diploid, 4 polyploid, and 10 aneuploid (9 with a single aneuploid G0G1 peak and 1 multiploid) by flow cytometry. The concordance rate between flow and image cytometry was 19 of 23 (83%); one case did not have flow cytometry available. Most embryonal rhabdomyosarcomas were aneuploid (10 of 12; 83%), and they had a high incidence of recurrence in Stages III and IV (4 of 12; 33%). Although aneuploidy in pediatric cancers may predict a therapeutic response and good prognosis, this was not supported by our findings in rhabdomyosarcoma. The tumor DNA content correlated with the clinical stage but not with the patient's clinical course or tumor histopathological type. DNA content did not appear to be as important a prognostic tool as tumor stage.

Adolescent↗

PubMed1990

St. Anthony's fire: successful reversal of ergotamine-induced peripheral vasospasm by hydrostatic dilatation.

A 60-year-old trauma victim developed severe ischemia of all four extremities following administration of heparin-dihydroergotamine as prophylaxis against deep venous thrombosis. Despite cessation of heparin-dihydroergotamine and infusion of intraarterial papaverine into the right femoral artery, both lower extremities progressed to frank gangrene and amputation (above-knee on the left and below-knee on the right). However, both ischemic upper extremities were salvaged following intraoperative hydrostatic dilatation with balloon catheters. Ergotism is an avoidable and potentially treatable cause of peripheral gangrene in the critically-ill patient.

Catheterization↗