Applications of gene replacement technology to Streptomyces clavuligerus strain development for clavulanic acid production

Cephamycin C production was blocked in wild-type cultures of the clavulanic acid-producing organism Streptomyces clavuligerus by targeted disruption of the gene (lat) encoding lysine epsilon-aminotransferase. Specific production of clavulanic acid increased in the lat mutants derived from the wild-type strain by 2- to 2.5-fold. Similar beneficial effects on clavulanic acid production were noted in previous studies when gene disruption was used to block the production of the non-clavulanic acid clavams produced by S. clavuligerus. Therefore, mutations in lat and in cvm1, a gene involved in clavam production, were introduced into a high-titer industrial strain of S. clavuligerus to create a double mutant with defects in production of both cephamycin C and clavams. Production of both cephamycin C and non-clavulanic acid clavams was eliminated in the double mutant, and clavulanic acid titers increased about 10% relative to those of the parental strain. This represents the first report of the successful use of genetic engineering to eliminate undesirable metabolic pathways in an industrial strain used for the production of an antibiotic important in human medicine.

Predisposition to hookworm infection in Papua New Guinea

Reinfection with hookworm (Necator americanus) following chemotherapy was studied over 8 years in a rural village in Madang Province, Papua New Guinea. Faecal egg counts were performed on up to 202 individuals in July 1988, August 1990 and November 1996; the study population was treated after sampling in 1988 and 1990. Reinfection burdens in 1996 did not differ significantly from pretreatment burdens (in 1988), and were significantly higher than burdens in 1990. However, the prevalence of hookworm infection was significantly lower in 1996 than in either 1988 or 1990. There was significant predisposition to high or low hookworm burden between 1990 and 1996; this predisposition was stronger in children than adults. However, there was no detectable predisposition between 1988 and 1996 in individuals who had been treated 2 or more times between surveys. The mean weight of adult hookworms in individual hosts was measured in 1988 and 1990 using worms expelled after chemotherapy. There was a significant positive correlation between mean male hookworm weight in the 2 years, suggesting that individual hosts are predisposed to infection with heavy or light hookworms. These data suggest that differences in host susceptibility are involved in generating predisposition, but that longer-term variation in either exposure or susceptibility limits the period over which significant predisposition can be detected.

Runaway pacemaker: a case report and review

We describe a case of runaway pacemaker. The differential diagnosis is discussed and a review of the literature is included for the diagnosis and treatment of pacemaker mediated tachycardia and runaway pacemaker.

Study of restriction fragment length polymorphism analysis and spoligotyping for epidemiological investigation of Mycobacterium bovis infection

Restriction fragment length polymorphism (RFLP) analysis with probes derived from the insertion element IS6110, the direct repeat sequence, and the polymorphic GC-rich sequence (PGRS) and a PCR-based typing method called spacer oligonucleotide typing (spoligotyping) were used to strain type Mycobacterium bovis isolates from the Republic of Ireland. Results were assessed for 452 isolates which were obtained from 233 cattle, 173 badgers, 33 deer, 7 pigs, 5 sheep, and 1 goat. Eighty-five strains were identified by RFLP analysis, and 20 strains were identified by spoligotyping. Twenty percent of the isolates were the most prevalent RFLP type, while 52% of the isolates were the most prevalent spoligotype. Both the prevalent RFLP type and the prevalent spoligotype were identified in isolates from all animal species tested and had a wide geographic distribution. Isolates of some RFLP types and some spoligotypes were clustered in regions consisting of groups of adjoining counties. The PGRS probe gave better differentiation of strains than the IS6110 or DR probes. The majority of isolates from all species carried a single IS6110 copy. In four RFLP types IS6110 polymorphism was associated with deletion of fragments equivalent in size to one or two direct variable repeat sequences. The same range and geographic distribution of strains were found for the majority of isolates from cattle, badgers, and deer. This suggests that transmission of infection between these species is a factor in the epidemiology of M. bovis infection in Ireland.

Ultrasound in obstetric triage

The use of limited ultrasound as a tool in obstetric triage has become increasingly popular. While most midwives only perform ultrasound in the third trimester, some institutions do include earlier sonographic testing as part of the midwifery management plan. This article addresses the professional issues related to limited ultrasound in obstetric triage protocol, the education and training needed to acquire the skill, the process for integrating the skill into clinical practice, and a discussion of obstetric triage procedures.

Guillain-Barré syndrome

The concepts of Guillain-Barré syndrome have changed substantially over the last 10 years, and the last 2 years have been no exception. Guillain-Barré syndrome is now recognized as a heterogeneous disorder with many clinical manifestations. Most current investigations are centered on the hypothesis of molecular mimicry. The major challenge now is to identify the precise mechanisms of nerve fiber injury and to determine how to prevent immune injury.

Cytosolic redox state mediates postischemic response to pyruvate dehydrogenase stimulation

Augmented pyruvate oxidation via pharmacological stimulation of pyruvate dehydrogenase (PDH) during reperfusion has been related to improved recovery of postischemic hearts independent of glycolytic activity. This study examined recovery of postischemic rabbit hearts during activation of PDH with dichloroacetate (DCA) in the presence of lactate, as a source of pyruvate, to determine the response to substrate-dependent changes in cytosolic redox state. After 10 min of ischemia, isolated hearts were reperfused with either 2.5 mM or 0. 5 mM pyruvate (Pyr) or 2.5 mM lactate (Lac), with or without 5 mM DCA. (13)C-enriched substrates allowed NMR assessment of metabolic perturbations. During normal perfusion, Pyr and Lac supported similar mechanical work. Increasing Pyr oxidation restored postischemic rate-pressure product to 82 +/- 4 and 88 +/- 6% of preischemic values during reperfusion with 2.5 and 0.5 mM Pyr, respectively, vs. 61 +/- 6 and 45 +/- 14% for untreated 2.5 and 0.5 mM Pyr, respectively (P < 0.05). In contrast, increasing Lac oxidation did not benefit recovery of RPP in untreated (44 +/- 7%) vs. DCA-treated 36 +/- 4% hearts. Thus the benefit of PDH activation for contractile recovery of postischemic hearts is mediated by the source of pyruvate, which also influences cytosolic redox state.

Predictors of homelessness among participants in a substance abuse treatment program

Risk factors for homelessness were examined prospectively among recent participants in a substance abuse treatment program. Low levels of support from friends, greater depression, and recent substance use were bivariately associated with homelessness two months following completion of the program. However, friend support was the only factor associated with homelessness after controlling for other significant bivariate predictors.

An analysis of silicone gel-filled breast implants: diagnosis and failure rates

This retrospective review analyzed 180 women who underwent explantation of 357 silicone gel-filled breast implants from September of 1991 to January of 1995. Implant status, including shell integrity and implantation times, was determined at the time of explantation. The age range of the patients was 25 to 75 years, with a mean age of 47 years. The age of the implants ranged from 0.5 to 24 years, with a mean age of 10.5 years. Of the 292 implants with known and documented integrity status, there were 102 intact, 76 unruptured with signs of leakage, and 114 ruptured. The frequency of implant rupture significantly increased with implant age. The average age of rupture was 13.4 years. The average age of signs of leakage was 10.1 years. There were no significant differences in failure rates among the implant types of four manufacturers. Analysis of both mammography and magnetic resonance imaging (MRI) as diagnostic modalities for differentiating intact implants, implant leakage, and implant rupture was performed. Standard mammography was less reliable in diagnosing implant leakage or rupture (sensitivity, 55 percent; specificity, 69 percent) than MRI (sensitivity, 72 percent; specificity, 82 percent). In conclusion, implant rupture occurred at a significantly increasing rate with implant age (10 to 15 years). These findings were independent of implant type or manufacturer. Mammography alone is a below-average diagnostic tool for detecting leakage or rupture, whereas MRI is a more accurate modality.

Safety and cost-effectiveness of early discharge after primary angioplasty in low risk patients with acute myocardial infarction. PAMI-II Investigators. Primary Angioplasty in Myocardial Infarction

OBJECTIVES

The second Primary Angioplasty in Myocardial Infarction (PAMI-II) study evaluated the hypothesis that primary percutaneous transluminal coronary angioplasty (PTCA), with subsequent discharge from the hospital 3 days later, is safe and cost-effective in low risk patients.

BACKGROUND

In low risk patients with myocardial infarction (MI), few data exist regarding the need for intensive care and noninvasive testing or the appropriate length of hospital stay.

METHODS

Patients with acute MI underwent emergency catheterization with primary PTCA when appropriate. Low risk patients (age <70 years, left ventricular ejection fraction >45%, one- or two-vessel disease, successful PTCA, no persistent arrhythmias) were randomized to receive accelerated care (admission to a nonintensive care unit and day 3 hospital discharge without noninvasive testing [n = 237] or traditional care [n = 234]).

RESULTS

Patients who received accelerated care had similar in-hospital outcomes but were discharged 3 days earlier (4.2+/-2.3 vs. 7.1+/-4.7 days, p = 0.0001) and had lower hospital costs ($9,658+/-5,287 vs. $11,604+/-6,125 p = 0.002) than the patients who received traditional care. At 6 months, accelerated and traditional care groups had a similar rate of mortality (0.8% vs. 0.4%, p = 1.00), unstable ischemia (10.1% vs. 12.0%, p = 0.52), reinfarction (0.8% vs. 0.4%, p = 1.00), stroke (0.4% vs. 2.6%, p = 0.07), congestive heart failure (4.6% vs. 4.3%, p = 0.85) or their combined occurrence (15.2% vs. 17.5%, p = 0.49). The study was designed to detect a 10% difference in event rates; at 6 months, only a 2.3% difference was measured between groups, indicating an actual power of 0.19.

CONCLUSIONS

Early identification of low risk patients with MI allowed safe omission of the intensive care phase and noninvasive testing, and a day 3 hospital discharge strategy, resulting in substantial cost savings.

Lead levels in high-risk and low-risk young children in the Minneapolis-St Paul metropolitan area

OBJECTIVES

To determine distribution of lead levels among children in a low-risk area; to validate a prescreening questionnaire; and to determine if universal lead screening is necessary in children in this area.

DESIGN

Blood lead levels and questionnaires were obtained on eligible patients. Data were analyzed using stepwise regression analysis.

SETTING

Community clinics and a health maintenance organization (HMO) in the Minneapolis-St Paul metropolitan area.

PATIENTS

A total of 9603 children at well-child visits, age 6 months to 6 years at community clinics, and 6 months to 3 years at the HMO.

OUTCOME MEASURES

Whole blood lead levels (WBLs) and questionnaires.

RESULTS

The total sample rate of WBLs at >/=10 microg/dL was 12%, at >/=15 microg/dL was 31/2%, and at >/=20 microg/dL was 1.2%. At both 10 microg/dL and 15 microg/dL, the non-HMO group was at higher risk. For both groups, risk factors included living in the central cities, and living in housing built before 1950. For the non-HMO group a history of the child eating paint chips, or the child or a sibling having previous lead poisoning were also risk factors.

CONCLUSIONS

Not all children need lead screening. Children living in the central cities, or with the risk factors of living in housing built before 1950 or a previous history of lead poisoning should be screened.

The modern CIO: forging a new role in the managed care era

The advent of managed care has helped forge new roles for healthcare professionals. Competitive pressures, the profile of the member community, and provider network design drive healthcare delivery via the managed care model. Careful analysis and design of the managed care model charts the success or failure of the health care delivery system--usually an integrated delivery system (IDS). Therefore, those healthcare organizations that have chosen to get on the managed care bandwagon must re-invent themselves, both culturally and technologically. The chief information officer (CIO) leads this technological revolution. To work effectively, the technological infrastructure of the IDS must be closely in line with enterprise goals and objectives. In the managed care environment the old information system (IS) approach of supporting the operational needs of individual departments simply will not work. The CIO's new role will be to master the concept of managed care to ensure that enterprise-wide needs for operational, clinical, and financial information are met, and that IS and enterprise goals are aligned. CIOs who have an intuitive grasp of the managed care environment--although their numbers are growing as managed care mushrooms--make up a minority group. They are a special breed with clearly definable qualities such as business savvy and an affinity for big-picture thinking. To an IDS, a CIO with these qualities is a rare gem indeed. This article introduces Don Winschel, the associate administrator and CIO of Johnson City Medical Center (Johnson City, TN) as an example of one such modern CIO.

Identification of a CG/LH binding site in two strains of Mycobacterium vaccae

We have previously reported the presence of a chorionic gonadotropin-like (CG-like) protein in the bacterium Xanthomonas maltophilia (X. maltophilia). We have also shown that X. maltophilia possesses a unique binding site for the native ligand and hCG, but not for human luteinizing hormone (hLH), and that binding of the native ligand or hCG to the receptor causes changes in the growth rates of culturing X. maltophilia. In this study we have characterized a CG/LH binding site in two strains of Mycobacterium vaccae. The binding site is specific for hCG and hLH, and Scatchard analysis reveals a biphasic, high affinity binding pattern. This is the second identified bacterial species to possess a CG-specific binding site.

New paradigms for new problems: expanding information technology in healthcare

As healthcare moves from individual fee-for-services and single hospital systems to capitated contracts and integrated delivery systems (IDS), and then into Community Health Information Networks (CHINs), implementing a data warehouse is a realistic way to collect and transform data into meaningful information. However, healthcare differs from other industries because of its complexity. The software is more specialized, and many vendors have adopted proprietary operating systems that hold critical data hostage. Even when available, data is not integrated and is more convoluted than in other industries. To have a complete patient profile, there can be 750 critical data elements in a healthcare transaction, as compared to an estimated 150 data elements in a financial transaction. Historical, behavioral, and diagnostic information is needed at multiple points along the continuum of care: physician's office, rehabilitation, pharmacy, emergency room, laboratory, and hospital. Additionally, these points along the continuum must communicate with the community they serve and the purchasers of healthcare. This article looks at data warehousing and the different technologies available for consolidating and integrating information in the healthcare environment.

Increased natural killer cells in fluids. A new, sensitive means of detecting carcinoma

OBJECTIVE

Natural killer (NK) cells are cells of undefined lineage that are capable of lysing certain tumor cell lines in vitro. Determination of NK cell percent (NK%) in effusions by flow cytometry could aid in the detection of malignancies.

STUDY DESIGN

Over a six-month period at the Houston Veterans Affairs Medical Center, fresh effusions were routinely processed for cytology, and a portion was submitted for lymphocyte immunophenotyping using the FACScan and a panel including CD16/CD56 for NK cells. Seventy fluids (42 pleural, 28 peritoneal) from 62 men were examined.

RESULTS

NK cell percents were markedly increased in 15 cases (29-68%, mean 45.5) and low in 55 (2-20%, mean 8). Fourteen of the 15 cases with increased NK% were positive for carcinoma (93%), while 54/55 cases with low ones were negative for carcinoma (98%). Mesotheliomas, lymphomas and leukemias had low NK%.

CONCLUSION

Using the Mann-Whitney U test, an increase in NK% predicts metastatic carcinoma with a P level of < .00001.

Patterns and mechanisms of in-stent restenosis. A serial intravascular ultrasound study

BACKGROUND

Studies have suggested that restenosis within Palmaz-Schatz stents results from neointimal hyperplasia or chronic stent recoil and occurs more frequently at the articulation.

METHODS AND RESULTS

Serial intravascular ultrasound (IVUS) was performed after intervention and at follow-up in 142 stents in 115 lesions. IVUS measurements (external elastic membrane [EEM], stent, and lumen cross-sectional areas [CSAs] and diameters) were performed, and plaque CSA (EEM lumen in reference segments and stent lumen in stented segments), late lumen loss (delta lumen), remodeling (delta EEM in reference segments and delta stent in stented segments), and tissue growth (delta plaque) were calculated. After intervention, the lumen tended to be smallest at the articulation because of tissue prolapse. At follow-up, tissue growth was uniformly distributed throughout the stent; the tendency for greater neointimal tissue accumulation at the central articulation reached statistical significance only when normalized for the smaller postintervention lumen CSA. In stented segments, late lumen area loss correlated strongly with tissue growth but only weakly with remodeling. Stents affected adjacent vessel segments; remodeling progressively increased and tissue growth progressively decreased at distances from the edge of the stent. These findings were similar in native arteries and saphenous vein grafts and in lesions treated with one or two stents. There was no difference in the postintervention or follow-up lumen (at the junction of the two stents) when overlapped were compared with nonoverlapped stents.

CONCLUSIONS

Late lumen loss and in-stent restenosis were the result of neointimal tissue proliferation, which tended to be uniformly distributed over the length of the stent.

Mechanisms and results of balloon angioplasty for the treatment of in-stent restenosis

Restenosis within tubular slotted stents is secondary to intimal hyperplasia and is usually treated with percutaneous transluminal coronary angioplasty (PTCA). Sequential intravascular ultrasound (IVUS) was used to assess the mechanisms and results of PTCA for in-stent restenosis. Sixty-four restenotic Palmaz-Schatz stents were studied by IVUS imaging before and after PTCA. IVUS measurements of stent and lumen cross-sectional areas (CSAs) at 5 segments (proximal and distal stent edges, proximal and distal stent bodies, and the central articulation) were used to calculate intimal hyperplasia CSA (stent-lumen CSA). The results of the 5 segments were then averaged. Mean and minimum CSAs were compared before and after PTCA. Quantitative angiographic measurements showed a minimal lumen diameter increase from 1.05 +/- 0.63 mm (mean +/- 1 SD) before intervention to 2.77 +/- 0.51 mm after PTCA (p < 0.0001). Conversely, the diameter stenosis decreased from 63 +/- 19% to 18 +/- 12% (p < 0.0001). IVUS measurements showed a minimum lumen CSA increase from 2.3 +/- 1.3 mm2 to 6.1 +/- 2.2 mm2 (p < 0.0001) as a result of an increased minimum stent CSA (7.2 +/- 2.4 mm2 to 8.7 +/- 2.6 mm2, p < 0.0001) and a decreased intimal hyperplasia CSA within the stent (4.9 +/- 2.2 mm2 to 2.7 +/- 2.0 mm2, p < 0.0001). Of the total mean lumen enlargement, 56 +/- 28% was the result of additional stent expansion and 44 +/- 28% was the result of a decrease in neointimal tissue. The minimum lumen CSA after PTCA was significantly smaller than the minimum stent CSA before PTCA (presumably an accurate reflection of lumen dimensions immediately after stent implantation; p = 0.0002). The mechanism of PTCA for restenosis is a combination of additional stent expansion and tissue extrusion out of the stent; there is a relatively high residual stenosis (angiographic diameter stenosis of 18 +/- 12%).