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Biomedical subjects

B Koch

Publications and source records attributed to B Koch.

At least 55 records · Page 3Linked to original sources
PubMed1998

Comparison between moexipril and atenolol in obese postmenopausal women with hypertension.

The present study investigated the effect of the new ACE-inhibitor moexipril versus the beta 1-adrenergic blocker atenolol on metabolic parameters, adverse events (AEs) and sitting systolic (SSBP) and sitting diastolic blood pressure (SDBP) in obese postmenopausal women with hypertension (stage I and II). After a 4-week placebo run-in phase, 116 obese, postmenopausal women with primary hypertension were randomised into two treatment groups receiving once daily dosages of either moexipril 7.5 mg or atenolol 25 mg initially (mean age: 57 +/- 7 years in both groups; mean weight: 94 kg in the moexipril group and 89 kg in the atenolol group, corresponding to a body mass index (BMI) of 35.2 kg/m2 and 34.1 kg/m2 in both groups, respectively). After 4 and 8 weeks, the dosages were uptitrated to moexipril 15 mg, or if necessary to moexipril 15 mg/hydrochlorothiazide (HCTZ) 25 mg, or to atenolol 50 mg and atenolol 50 mg/HCTZ 25 mg, in patients whose blood pressure was not sufficiently controlled. At endpoint, metabolic parameters (total cholesterol, triglycerides, LDL, HDL, glucose, insulin) were not significantly altered in either treatment group. Most frequent adverse events under monotherapy (moexipril/atenolol) were asthenia (5.3/13.0%), headache (13.2/21.7%), cough (7.9/6.5%), pharyngitis (21.1/8.7%) and peripheral oedema (5.3/13.0%). Overall at least one AE was reported in 66% of the patients treated with moexipril and in 78% of those treated with atenolol. Reduction of SSBP/SDBP at endpoint was 14.7 +/- 1.9/10.0 +/- 1.1 and 8.7 +/- 1.9/8.4 +/- 1.1 mmHg after treatment with moexipril and atenolol, respectively. The results showed that moexipril and atenolol are equally effective in reducing blood pressure without adversely affecting blood lipids and carbohydrate metabolism.

Adrenergic beta-Antagonists↗
PubMed1998

Prophylactic thyroidectomy in 75 children and adolescents with hereditary medullary thyroid carcinoma: German and Austrian experience.

When mutations of the RETproto-oncogene were found in 1993 to account for hereditary medullary thyroid carcinoma (MTC), surgeons obtained the opportunity to operate on patients prophylactically (i. e., at a clinically asymptomatic stage). Whether this approach is justified, and, if so, when and to which extent surgery should be performed remained to be clarified. A questionnaire was sent to all surgical departments in Germany and Austria. All of the patients who fulfilled the following criteria were enrolled: (1) preoperatively proved RET mutation; (2) age </= 20 years, (3) clinically asymptomatic thyroid C cell disease; and (4) TNM classification pT0-1/pNX/pN0-1/M0. Seventy-five patients were identified, and fifteen mutations were detected in six codons. Two adolescents had unilateral pheochromocytomas as part of the multiple endocrine neoplasia II (MEN-II) syndrome. No hyperparathyroidism was noted. All patients underwent total thyroidectomy, and 57 patients went on to have lymph node dissection. Parathyroid glands were removed in 34 patients and autografted in 11. Histopathology revealed MTC in 46 patients (61%, youngest 4 years); C cell hyperplasia (CCH) only was detected in the other 29 patients. Three patients had lymph node metastases (LNMs) the youngest being age 14 years. Calcitonin levels were not useful for differentiating between CCH and MTC, but in all patients with LNMs at least the stimulated calcitonin levels were assayed. After surgery, five patients (6.7%) sustained permanent hypoparathyroidism, and one patient (1.3%) had a permanent unilateral recurrent nerve palsy. All but three patients (96%) were biochemically cured. In conclusion, prophylactic total thyroidectomy can be performed safely in experienced centers. We recommend prophylactic total thyroidectomy at age 6. Cervicocentral lymph node dissection should be included when calcitonin levels are elevated or if patients are older than 10 years. Bilateral lymph node dissection should be performed if LNMs are suspected or when patients with elevated calcitonin are older than 15 years.

Adolescent↗
PubMed1998

Melanocortin receptors and delta-opioid receptor mediate opposite signalling actions of POMC-derived peptides in CATH.a cells.

The locus coeruleus is innervated by proopiomelanocortin (POMC)-derived peptide immunoreactive fibres. The biological effects of ( melanocyte-stimulating hormone (aMSH) and [-endorphin on second messengers (cAMP, inositol phosphates) and gene transcription were studied in the locus cceruleus-derived cell line CATH.a. RT-PCR analysis revealed the presence of four MSH receptor subtypes (1, 3, 4 and 5). Activation of these receptors by diacetyl alphaMSH stimulated cAMP accumulation in a dose-dependent manner (EC50: 4 x 10(-9) M). Diacetyl alphaMSH stimulated transcription from reporter genes driven by the c-fos or tyrosine hydroxylase promoter. This effect was abolished when protein kinase A was inactivated with a dominant inhibitory mutant. RT-PCR analyses revealed the presence of delta-, but not mu-and kappa-opioid receptor. Pharmacological analysis showed that beta-endorphin (EC50: 2.5 x 10(-8)M), but not N-acetyl beta-endorphin, antagonized the biological effect of diacetyl alphaMSH on cAMP production and gene transcription. Since N-acetylation regulates the biological activity of alphaMSH and beta-endorphin in an opposite manner, we propose a model where the rate of secretion dictated by the bioelectric activity of the presynaptic neuron modulates POMC-derived peptide maturation and the resulting biological signal sensed by the postsynaptic plate.

Acetylation↗
PubMed1998

Continuous activation of pituitary adenylate cyclase-activating polypeptide receptors elicits antipodal effects on cyclic AMP and inositol phospholipid signaling pathways in CATH.a cells: role of protein synthesis and protein kinases.

Continuous exposure of cells to agonists develops a process that determines the extent to which the cells eventually respond to further stimuli. Here we used CATH.a cells (a catecholaminergic neuron-like cell line), which express pituitary adenylate cyclase-activating polypeptide (PACAP) receptors linked to both adenylyl cyclase and phospholipase C-beta pathways, to investigate the influence of prolonged hormonal treatment on dual signaling and gene transcription. Prolonged incubation of cells with PACAP failed to down-regulate the density and affinity of membrane binding sites and caused opposite changes in messenger systems: PACAP-stimulated cyclic AMP accumulation was attenuated in a time- and dose-dependent fashion (t(1/2) = 6.7 h and IC50 = 0.1 nM), whereas phosphoinositide turnover was overstimulated. Both effects were insensitive to pertussis toxin, whereas the drop in cyclic AMP concentration was also unchanged in the presence of 3-isobutyl-1-methylxanthine, indicating that neither Gi-like proteins nor cyclic nucleotide phosphodiesterases play a critical role in these processes. Blockade of protein synthesis with cycloheximide, as well as inhibition by H89 of cyclic AMP-dependent protein kinase (but not by bisindolylmaleimide of protein kinase C) antagonized the influences exerted by PACAP on adenylyl cyclase activity and inositol phosphate formation. Transcription of the chimeric GAL4-CREB construct, transiently transfected into CATH.a cells, was stimulated by PACAP, and this effect was potentiated as a result of chronic PACAP treatment. The results of the present investigation provide new insight into the possible differential regulation and cross-talks of transduction signals of receptors linked to multiplex signaling. They demonstrate that prolonged exposure of CATH.a cells to PACAP results in the desensitization of the cyclic AMP pathway and superinduction of the inositol phosphate signal, through protein neosynthesis and cyclic AMP-dependent protein kinase activation. At the same time, they show that desensitization of cyclic AMP signaling not only fails to hamper, but actually amplifies PACAP-stimulated CREB-regulated transcription.

Cell Line↗
PubMed1998

Induced levels of heat shock proteins in a dnaK mutant of Lactococcus lactis.

The bacterial heat shock response is characterized by the elevated expression of a number of chaperone complexes and proteases, including the DnaK-GrpE-DnaJ and the GroELS chaperone complexes. In order to investigate the importance of the DnaK chaperone complex for growth and heat shock response regulation in Lactococcus lactis, we have constructed two dnaK mutants with C-terminal deletions in dnaK. The minor deletion of 65 amino acids in the dnaKDelta2 mutant resulted in a slight temperature-sensitive phenotype. BK6, containing the larger deletion of 174 amino acids (dnaKDelta1), removing the major part of the inferred substrate binding site of the DnaK protein, exhibited a pronounced temperature-sensitive phenotype and showed altered regulation of the heat shock response. The expression of the heat shock proteins was increased at the normal growth temperature, measured as both protein synthesis rates and mRNA levels, indicating that DnaK could be involved in the regulation of the heat shock response in L. lactis. For Bacillus subtilis, it has been found (A. Mogk, G. Homuth, C. Scholz, L. Kim, F. X. Schmid, and W. Schumann, EMBO J. 16:4579-4590, 1997) that the activity of the heat shock repressor HrcA is dependent on the chaperone function of the GroELS complex and that a dnaK insertion mutant has no effect on the expression of the heat shock proteins. The present data from L. lactis suggest that the DnaK protein could be involved in the maturation of the homologous HrcA protein in this bacterium.

Bacterial Proteins↗
PubMed1998

Antihypertensive treatment in postmenopausal women: results from a prospective, randomized, double-blind, controlled study comparing an ACE inhibitor (moexipril) with a diuretic (hydrochlorothiazide).

The present study was designed to compare the safety and efficacy of the new angiotensin-converting enzyme inhibitor moexipril with that of hydrochlorothiazide (HCTZ) in postmenopausal women with mild-to-moderate hypertension. After a 4-week single-blind placebo period, 97 postmenopausal hypertensive women (42-74 years of age) with a sitting diastolic blood pressure (SDBP) of 95-114 mm Hg were randomized to receive either once daily moexipril 15 mg or HCTZ 25 mg for a 12-week double-blind treatment period. At study endpoint, HCTZ caused significantly greater increases from baseline in serum uric acid levels than did moexipril (0.8 +/- 0.1 vs. 0.1 +/- 0.1 mg/dl, p < 0.01). Furthermore, 12-week treatment with HCTZ resulted in significant increases in glucose (+11.0 +/- 4.1 mg/dl) and total cholesterol/HDL ratio (+0.3 +/- 0.1 mg/dl) and a significant decrease in HDL (-3.2 +/- 0.7 mg/dl). In contrast, moexipril treatment was not associated with significant changes in any metabolic parameter. Both drugs efficiently lowered SDBP with reductions of -10.0 +/- 1.3 and -11.8 +/- 1.1 mm Hg in the moexipril and HCTZ group, respectively. Clinical adverse events were reported by a greater percentage of HCTZ patients (53%) than moexipril patients (40%), with headache and rhinitis as the most frequent events. The results indicate that moexipril was better tolerated than HCTZ in postmenopausal women and did not adversely affect metabolic parameters. Both drugs were effective in lowering blood pressure.

Adult↗
PubMed1998

[Quantitative determination of cell composition of human granulation tissue by fluorescence activated cell sorting (FAC)].

Granulation tissue of normal and non-healing human wounds showed a similar distribution pattern of the cell populations investigated by FACS analysis, whereas only non-healing wounds revealed a reduced density of cells and intercellular matrix. Thus, supporting the thesis that impaired wound healing is not caused by changes of the cellular distribution pattern of granulation tissue, but possibly by lessened cell function.

Cell Count↗
PubMed1998

[Quality assurance in rheumatology--the rheumatologic anamnesis].

The systemic character of the rheumatic diseases has to be considered in the interview of a patient with rheumatic symptoms. It is the aim of this article to point to the importance of the anamnesis as part of the quality control in rheumatology and to present a short list of concise questions which proved to be valuable when dealing with patients with rheumatic symptoms. A physician not trained in rheumatology should be enabled to appreciate extraarticular symptoms in the context of the systemic nature of the rheumatic diseases.

Germany↗
PubMed1998

Comparison of seroprevalences of human herpesvirus-6 and -7 in healthy blood donors from nine countries.

BACKGROUND AND OBJECTIVES: The purpose of the study was to register antibody prevalences of HHV-7 in various locations of the world in comparison to the closely related HHV-6. MATERIALS AND METHODS: Sera of healthy blood donors from nine countries in five continents were titered by indirect immunofluorescent assays using HHV-6 infected HSB2 and HHV-7 infected SupT1 cells. RESULTS: Antibody prevalence for HHV-7 is high (75-98%) in practically all countries except for Northern Japan (44%), with no simple correlation to elevated HHV-6 antibody titers. There were regions of low, intermediate and high mean antibody titers against HHV-7 such as 78.5-91.3 for Belgium, Israel, Japan, USA and Australia, 175.4-182.6 for Mexico and Cologne/Germany, and 389.2 for South Africa for which geographic characteristics may be responsible. CONCLUSION: HHV-7, similar to HHV-6, is a widespread human herpesvirus with elevated antibody titers in the healthy human population essentially everywhere. The data warrant further studies to evaluate its possible pathologic potential, preferentially in persons with defective immune responses.

Adolescent↗
PubMed1997

A fatal case of severe SLE complicated by invasive aspergillosis.

We report on the case of a 25-year-old female with severe systemic lupus erythematosus (SLE) who presented with pancytopenia, fever, arthralgia and abdominal pain. After antibiotic treatment, the patient was afebrile for 3 days before her temperature rose again. Dyspnoea and cough pointed towards pneumonia which was confirmed by X-ray. Different antibiotics and the antimycotic agent fluconazol were given. The lupus flare was treated with high-dose prednisolone. After a couple of days, the dyspnoea increased and mechanical ventilation became necessary. Bronchoscopy and transbronchial biopsy revealed the diagnosis of invasive aspergilloses. Despite of an immediate treatment with amphotericin B, the patient died because of respiratory insufficiency. The literature on aspergillosis in SLE is reviewed and prophylactic, diagnostic and therapeutic options are discussed for this infectious complication which has an 80% mortality in patients with SLE.

Adult↗
PubMed1997

Podocytes are the major source of IL-1 alpha and IL-1 beta in human glomerulonephritides.

To address the question of in situ production of IL-1 alpha and IL-1 beta in proliferative and non-proliferative forms of human glomerulonephritis (GN), we performed immunocytochemical and in situ hybridization studies on renal biopsies from patients with mesangial IgA-GN (N = 38), idiopathic membranous GN (MGN; N = 12), minimal change disease (MCD; N = 9), focal segmental glomerulosclerosis (FSGS; N = 5) and acute endocapillary GN (AGN; N = 3). Normal kidneys (N = 10) served as controls. Concomitantly, the expression of IL-1 receptor type I (IL-1 RI), IL-1 receptor type II (IL-1 RII) and of IL-1 receptor antagonist (IL-1 RA) was analyzed. Antibodies against antigens expressed on podocytes (PP-44), endothelial cells (CD31) and monocytes/macrophages (CD11b, CD14, CD68) were applied to attribute the expression of IL-1/IL-1 related peptides to intrinsic glomerular and/or blood-derived infiltrating cells. Our results demonstrate that IL-1 RII is constitutively expressed on endothelial cells, and its expression can be induced in proximal tubular cells and in the interstitium. In diseased glomeruli podocytes are capable of producing IL-1 alpha/beta. In MGN and MCD/FSGS, the expression of both IL-1 forms is particularly noted in early stages of the disease and is not only accompanied by a marked reactivity for IL-1 RI, but also for IL-1 RA. In segmental sclerosing lesions in FSGS and in IgA-GN with marked glomerular proliferation and/or sclerosis, a reduced expression of the PP-44 antigen and a diminished ability of podocytes to produce IL-1/IL-1 related peptides are noted. These results suggest that intrinsic glomerular production of IL-1 may be of relevance for the protection of glomeruli from continuing injury.

Acute Disease↗
PubMed1997

Antihypertensive treatment with moexipril plus HCTZ vs metoprolol plus HCTZ in patients with mild-to-moderate hypertension.

Combination therapy with the new ACE inhibitor moexipril plus hydrochlorothiazide (HCTZ) results in significant blood pressure (BP) reductions. This study compares the efficacy and safety of moexipril plus HCTZ to that of a standard combination treatment in patients with mild-to-moderate hypertension. After a 1 month placebo run-in period, 140 hypertensive patients whose sitting diastolic BP (DBP) averaged 95-114 mm Hg were randomized to receive either once daily moexipril 7.5 mg/HCTZ 12.5 mg or metoprolol 100 mg/HCTZ 12.5 mg for the following 12-week double-blind treatment period. At biweekly visits BP was controlled sphygmomanometrically and the occurrence of adverse events (AE) was documented. At study endpoint adjusted mean reductions in sitting systolic/diastolic BP seen with both combinations were -17.6 mm Hg/-12.8 mm Hg and -17.2 mm Hg/-13.9 mm Hg in the moexipril/HCTZ and metoprolol/HCTZ groups, respectively. The response rate to both kinds of combinations were very similar, 69% and 74% in the moexipril/HCTZ and metoprolol/HCTZ groups, respectively. The percentage of patients which experienced one or more AEs were 46% in the moexipril/HCTZ and 61% in the metoprolol/HCTZ group. Headache and cough which are the most frequently reported AEs after treatment with ACE inhibitors were seen in 9% and 10% of the patients in the moexipril/HCTZ group compared to 10% and 4% in the metoprolol/HCTZ group. The study indicates that the combination of moexipril 7.5 mg plus HCTZ 12.5 mg is as efficacious and safe as metoprolol 100 mg plus HCTZ 12.5 mg in the treatment of mild-to-moderate hypertension.

Adult↗
PubMed1997

Pituitary adenylate cyclase-activating polypeptide triggers dual transduction signaling in CATH.a cells and transcriptionally activates tyrosine hydroxylase and c-fos expression.

We used a catecholaminergic neuron-like cell line (CATH.a cells) as a model system to investigate the likelihood that pituitary adenylate cyclase-activating polypeptide (PACAP) may participate in the regulation of specific gene expression in catecholaminergic neurons. Analysis by reverse transcriptase-PCR amplification revealed the presence in these cells of type I PACAP receptors, with a short isoform, together with a heavier so-called Hop splice variant. PACAP38 and PACAP27 enhanced, in a dose-dependent manner, both cyclic AMP formation and phosphoinositide breakdown, with EC50 values of, respectively, 0.6 x 10(-10) and 2 x 10(-9) M. These peptides, in addition, also elevated [Ca2+]i by mobilizing intracellular calcium pools. Vasoactive intestinal peptide (VIP) was approximately 1,000-fold less potent in stimulating cyclic AMP (with EC50 = 2 x 10(-7) M) and failed to change the turnover of phosphoinositides and to alter [Ca2+]i. Both forms of PACAP, as well as forskolin, stimulated transcriptional induction of tyrosine hydroxylase (TH) and c-fos promoters fused to a chloramphenicol acetyltransferase (CAT) reporter gene in transiently transfected cells (p < 0.01 vs. controls). Induction of CAT activity linked to both TH and c-fos promoters was obliterated upon coexpression of a dominant inhibitory mutant (Mt-RAB) of cyclic AMP-dependent protein kinase. We conclude that CATH.a cells do express functional PACAP type I receptors, the activation of which impinges on TH and c-fos transcription according to a process that is primarily dependent on the cyclic AMP-PKA pathway.

Adenylyl Cyclases↗
PubMed1997

High levels of circulating adrenomedullin in severe illness: correlation with C-reactive protein and evidence against the adrenal medulla as site of origin.

Adrenomedullin (AM) is a novel vasorelaxing peptide which was originally isolated from the extracts of human pheochromocytoma. It is produced by a number of organs among which the adrenal gland exhibits by far the highest concentrations. The peptide circulates in blood and its plasma levels have been reported to be increased in several diseases such as renal failure and sepsis. In the present study plasma concentrations of AM were measured in various forms of severe illness and compared to clinical and biochemical parameters in order to gain an insight into the factors controlling the plasma levels of this peptide. The highest concentrations of AM were found in patients with sepsis (344.4 +/- 60.4 pg/ml, n = 16) who exhibited up to 12-fold higher levels than a group of healthy subjects (74.1 +/- 4.1 pg/ml, n = 20). Markedly elevated levels were also measured in hemorrhagic (250.1 +/- 37.9 pg/ml, n = 9) and cardiogenic (216.2 +/- 29.4 pg/ml, n = 7) shock as well as in patients with cancer of the gastrointestinal tract (155.6 +/- 32.5 pg/ml, n = 11) or the lungs (146.5 +/- 19.1 pg/ml, n = 22). Plasma AM levels were positively correlated with serum creatinine concentrations in shock (r = 0.06, p < 0.001) and with C-reactive protein levels in patients with cancer (r = 0.64, p < 0.001) or sepsis (r = 0.63, p < 0.01). In order to examine the potential role of the adrenal gland as a site of AM release, hypoglycemia was induced in a group of healthy volunteers by graded infusion of insulin. Despite a more than 20-fold increase in plasma adrenalin indicating maximal stimulation of the adrenal medulla, no significant alterations of the plasma AM levels were observed. The study demonstrates that not only sepsis but also various forms of cancer and shock are associated with high levels of circulating AM. The correlation with C-reactive protein levels suggests a role of cytokines in mediating the elevations in plasma AM observed in sepsis and cancer. Reduced clearance of the peptide by the kidneys may be one of the mechanisms involved in the accumulation of AM in shock. The adrenal gland appears not to be a major source for circulating AM.

Adrenal Medulla↗
PubMed1997

PACAP type I receptor activation promotes cerebellar neuron survival through the cAMP/PKA signaling pathway.

The molecular nature, transduction pathways, and neurotrophic functions of pituitary adenylate cyclase activating peptide (PACAP) receptors were studied in primary culture of rat cerebellar granule cells. We show that cerebellar neurons express several PACAP type I receptor (PVR I) isoforms, including the short (PVR Is) and the Hop (PVR I-Hop) splice variants, the latter being restricted to neurons and not found in cerebellar glial cell cultures. In vitro, cerebellar granule cells die rapidly in the absence of a high concentration of K+ (25 mM), as demonstrated by TUNEL histochemistry, which shows that K+ deprivation induces massive neuronal apoptosis within 12 hr. This effect was reversed by PACAP 27 and 38. Both forms of PACAP prevent DNA fragmentation and allow long-term neuronal survival in the absence of high K+ (as shown by MAP2 immunostaining) and stimulate a reporter gene driven by the full-length c-fos promoter. These effects of PACAP are fully abolished upon transient transfection of cells with a dominant inhibitory mutant of the cAMP-dependent protein kinase (PKA). Taken together, these results show that in cerebellar granule neurons, PACAP type I receptors regulate gene expression and promote neuronal survival through the cAMP/PKA pathway.

Animals↗
PubMed1997

Usefulness of moexipril and hydrochlorothiazide in moderately severe essential hypertension.

The purpose of this study was to assess the efficacy and tolerability of the angiotensin-converting enzyme inhibitor moexipril alone and in combination with hydrochlorothiazide versus hydrochlorothiazide monotherapy in patients with stage II and III essential hypertension. This was a double-blind, randomized, multicenter trial that evaluated moexipril (15 and 30 mg once daily), hydrochlorothiazide (25 and 50 mg once daily), and combinations of the drugs (15 mg moexipril/25 mg hydrochlorothiazide and 30 mg moexipril/50 mg hydrochlorothiazide) in 272 hypertensive patients whose seated diastolic blood pressure (BP) was 100 to 114 mm Hg. The primary efficacy variable was the mean change from baseline in seated diastolic BP at the end of the dosing period. Secondary efficacy measures included changes in systolic BP and standing BP. The lower doses of moexipril and hydrochlorothiazide reduced diastolic BP similarly (-8.0 +/- 1.4 versus -8.1 +/- 1.4 mm Hg; p = NS) as did higher doses of the monotherapeutic regimens (moexipril, -9.7 +/- 1.2 mm Hg versus hydrochlorothiazide, -11.0 +/- 1.2 mm Hg, p = NS). Combinations of moexipril and hydrochlorothiazide reduced diastolic BP significantly more than either monotherapy (lower doses, -16.0 +/- 1.4 mm Hg; p < 0.001; higher doses, -17.9 +/- 1.2 mm Hg; p < 0.001). Similar trends were observed for the systolic BP. Discontinuation rates due to adverse events were 0% for the moexipril monotherapy patients and 3% to 5% in patients on diuretic or combination treatment. These data demonstrate that 15 and 30 mg moexipril once daily lower BP similarly to hydrochlorothiazide in patients with stage II and III hypertension. There is also an additive effect when combining the two agents that lowers BP more significantly than either monotherapy.

Adult↗
PubMed1997

Construction of specific erythromycin resistance mutations in the temperate lactococcal bacteriophage TP901-1 and their use in studies of phage biology.

A method for the construction and isolation of specifically designed mutations of the temperate lactococcal phage TP901-1 has been developed. Two different erm-labeled mutants were isolated. One was shown to be defective in lysogenization and excision. The other, showing normal lysogenization, was used for host range studies.

Bacteriophages↗