Korean Nationwide Surveillance of Antimicrobial Resistance of bacteria in 1997

Antimicrobial-resistant bacteria are known to be prevalent in tertiary-care hospitals in Korea. Twenty hospitals participated to this surveillance to determine the nationwide prevalence of resistance bacteria in 1997. Seven per cent and 26% of Escherichia coli and Klebsiella pneumoniae were resistant to 3rd-generation cephalosporin. Increased resistance rates, 19% of Acinetobacter baumannii to ampicillin/sulbactam, and 17% of Pseudomonas aeruginoa to imipenem, were noted. The resistance rate to fluoroquinolone rose to 24% in E. coli, 56% in A. baumannii and 42% in P. aeruginosa. Mean resistance rates were similar in all hospital groups: about 17% of P. aeruginosa to imipenem, 50% of Haemophilus influenzae to ampicillin, 70% of Staphylococcus aureus to methicillin, and 70% of pneumococci to penicillin. In conclusion, nosocomial pathogens and problem resistant organisms are prevalent in smaller hospitals too, indicating nosocomial spread is a significant cause of the increasing prevalence of resistant bacteria in Korea.

Direct identification of Vibrio vulnificus in clinical specimens by nested PCR

This study was performed to establish optimal nested PCR conditions and a high-yield DNA extraction method for the direct identification of Vibrio vulnificus in clinical specimens. We designed two sets of primers targeting the V. vulnificus hemolysin/cytolysin gene. The target of the first primer set (P1-P2; sense, 5'-GAC-TAT-CGC-ATC-AAC-AAC-CG-3', and antisense, 5'-AGG-TAG-CGA-GTA-TTA-CTG-CC-3', respectively) is a 704-bp DNA fragment. The second set (P3-P4; sense, 5'-GCT-ATT-TCA-CCG-CCG-CTC-AC-3', and antisense, 5'-CCG-CAG-AGC-CGT-AAA-CCG-AA-3', respectively) amplifies an internal 222-bp DNA fragment. We developed a direct DNA extraction method that involved boiling the specimen pellet in a 1 mM EDTA-0.5% Triton X-100 solution. The new DNA extraction method was more sensitive and reproducible than other conventional methods. The DNA extraction method guaranteed sensitivity as well, even when V. vulnificus cells were mixed with other bacteria such as Escherichia coli or Staphylococcus aureus. The nested PCR method could detect as little as 1 fg of chromosomal DNA and single CFU of V. vulnificus. We applied the nested PCR protocol to a total of 39 serum specimens and bulla aspirates from septicemic patients. Seventeen (94.4%) of the 18 V. vulnificus culture-positive specimens were positive by the nested PCR. Eight (42.1%) of the 19 culture-negative samples gave positive nested PCR results.

A case of arteriovenous type cardiac hemangioma

Cardiac hemangiomas are rare primary tumors of the heart and constitute only 2.8% of primary cardiac tumors. They are classified into capillary, cavernous, epitheloid and arteriovenous type and the last one is the most uncommon type. We experienced a case of cardiac hemangioma which was diagnosed as arteriovenous type for the first time in Korea in the literature. The patient was a 54-year-old woman who presented with palpitation and anterior chest pain. The diagnosis was based upon coronary angiography which showed two tumor blushings located in the interatrial and interventricular septum with venous drainage to the coronary sinus and right atrium. Associated atrial fibrillation with rapid ventricular response was controlled with digitalis.

Fatal Hormonema dematioides peritonitis in a patient on continuous ambulatory peritoneal dialysis: criteria for organism identification and review of other known fungal etiologic agents

We report a fatal case a fungal peritonitis caused by the yeast-like dematiaceous mould Hormonema dematioides in a 45-year-old woman. The woman had a 13-year history of insulin-dependent diabetes mellitus and had been on continuous ambulatory peritoneal dialysis for chronic renal failure. H. dematioides was repeatedly isolated from the dialysate culture specimens collected on days 3, 9, 16, and 20 of her hospital stay. Preliminary culture reports on day 7 of the growth of a yeast-like fungus, a probable Candida species, prompted the administration of fluconazole (FLU). Intraperitoneal and intravenous FLU failed to eliminate the mould, and the patient expired on day 21 of her hospital stay. We use this case to present what appears to be the first report of fungal peritonitis due to H. dematioides, to provide laboratorians with criteria for differentiating this organism from the similar mould Aureobasidium pullulans and from various yeast genera, and to provide a review of known fungal taxa inciting peritonitis.

Analysis of the gene encoding cyclomaltodextrinase from alkalophilic Bacillus sp. I-5 and characterization of enzymatic properties

The gene encoding cyclomaltodextrinase (CDase) was cloned from alkalophilic Bacillus sp. I-5. The nucleotide sequence of the gene was determined and the physicochemical properties of the enzyme were investigated. The gene had an open reading frame of 559 amino acids with a predicted molecular weight of 64,884. The enzyme was purified to near homogeneity from Escherichia coli cells carrying a recombinant plasmid that contained the CDase gene. The enzyme hydrolyzed cyclomaltoheptaose (beta-CD) 13 times better than starch and 33 times better than pullulan, and it had transglycosylation activity. The enzyme also hydrolyzed acarbose, a pseudotetrasaccharide inhibitor of glucosidases. The enzyme was stabilized by Ca2+ and the activity was increased more than twofold in the presence of 5 mM EDTA. The optimum temperature of the enzyme was elevated from 40 to 50 degrees C by Ca2+ ion and the thermal activity was maintained more than 80% at 60 degrees C in the presence of Ca2+. Comparison of known amino acid sequences of several amylolytic enzymes with cyclomaltodextrinase activity, site-directed mutagenesis of the enzyme, and substrate specificity of the enzyme imply that the region between the third and the fourth conserved regions of the enzyme may play an important role in binding and degradation of cyclomaltodextrin.

Effects of t-butyl hydrogen peroxide on single SR calcium release channels

Using lipid bilayer reconstitution technique, we investigated the oxidation effect of t-butyl hydrogen peroxide (tBHP) on the single channel activity of the sarcoplasmic reticulum (SR) calcium release channels isolated from canine latissimus dorsi muscles. When 0.7% tBHP was added in the cytosolic side, the channel activity became suppressed (n = 7), and it was recovered by changing the solution to the control solution. The suppression was due to the change in the gating mode of the channel: before tBHP the channel opened to four sub-conductance levels, but it opened to only one level after tBHP. These effects by tBHP were different from the previous finding using hydrogen peroxide (H2O2), which may be explained by different oxidation patterns between the two oxidants.

Nitric oxide directly activates calcium-activated potassium channels from rat brain reconstituted into planar lipid bilayer

Using the planar lipid bilayer technique, we tested whether NO directly activates calcium-activated potassium (Maxi-K) channels isolated from rat brain. We used streptozotocin (STZ) as NO donor, and the NO release was controlled with light. In the presence of 100-800 microM STZ, the Maxi-K channel activity increased up to 3-fold within several tens of seconds after the light was on, and reversed to the control level several minutes after shutting off the light. Similar activation was observed with other NO donors such as S-nitroso-N-acetylpenicillamine and sodium nitroprusside. The degree of activity increase was dependent upon the initial open probability (P[init]). When the P(init) was lower, the activity increase was greater. These results demonstrate that NO can directly affect the Maxi-K channel activity, and suggest that the Maxi-K channel might be one of the physiological targets of NO in brain.

Parathyroid hormone-related protein enhances insulin-like growth factor-I expression by fetal rat dermal fibroblasts

Interactions between cells of differing embryonic origins comprise a common theme during tissue development and repair. Often, communication between them can be mediated by soluble growth mediators and in some cases is restricted in focus. That is, some cells respond to, but do not produce, mediators expressed by other cells within the tissue. Because keratinocytes respond to but do not express insulin-like growth factor I (IGF-I), another skin cell population, the dermal fibroblast, may supply this factor. However, keratinocytes express, but do not respond to parathyroid hormone related protein (PTHrp), which increases cAMP production by dermal fibroblasts. Based on earlier results where inducers of cAMP increase local IGF-I expression in skeletal tissue, we postulated that PTHrp might induce local IGF-I by dermal fibroblasts and provide a source of this factor for keratinocyte activity. Our studies reveal that IGF-I mRNA and protein levels increase in response to PTHrp in vitro, and that this effect is replicated by inducers of cAMP, but not by activators of protein kinase C. Consequently, these factors appear to comprise a paracrine loop within the skin, permitting focused but restricted IGF-I expression to support skin growth, remodeling, or repair.

Secondary craniofacial management following initial correction of nonsyndromic craniosynostosis

Marked technical improvements in the surgical management of craniosynostosis have come hand-in-hand with refinements in anesthesia, intensive care, and radiographic image analysis. At the beginning of the second century of the care of these patients, we now have a variety of sophisticated options that represent safer, more physiologically sound and aesthetically more pleasing options for the correction of secondary problems in craniosynostosis.

Molecular epidemiologic analysis of Staphylococcus aureus isolated from clinical specimens

Nosocomial infections caused by Staphylococcus aureus are clinically serious and control of such infections requires strain typing to identify the source of contamination. Recently, pulsed-field gel electrophoresis (PFGE) and random amplified polymorphic DNA (RAPD) assay have been introduced and have provided a high level of strain discrimination of S. aureus isolated from clinical specimens. This study was performed to classify 82 strains of S. aureus isolated from 4 hospitals in the Kwangju-Chonnam area by PFGE and RAPD assay. Methicillin-resistant S. aureus (MRSA) was identified by disk diffusion method using the oxacillin disk and polymerase chain reaction of mecA gene was done in 69 strains. Eight-three strains including S. aureus ATCC 25923 were classified into 10 groups by RAPD assay, and into 8 groups by PFGE. Classified groups were not related to area or hospital. Classification was not characteristic between MRSA and methicillin-susceptible strains. Nosocomial infections due to outbreak were suggested because some strains disclosed identical band patterns by PFGE. These results indicate that medical personnels and instruments are routes of nosocomial infections caused by MRSA. PFGE and RAPD assay are powerful tools for the epidemiological study of S. aureus, but PFGE is more effective than RAPD assay. RAPD assay needs optimal combination of primers.

Molecular typing of Vibrio vulnificus isolates by random amplified polymorphic DNA (RAPD) analysis

This study was undertaken to determine molecular types and genetic similarity among V. vulnificus isolates by RAPD analysis. We compared these results with serotypes of V. vulnificus. Ninety-seven V. vulnificus strains including 69 strains from Chonnam University Hospital (CUH; Kwangju, Korea), 13 from Wonkwang University Hospital (WUH; Iksan, Korea), 13 from the Japanese National Institute of Health (JNIH) and two reference strains (ATCC 33815 and ATCC 27562) were analyzed. Four molecular types comprising all the strains were obtained by RAPD analysis. Type I was the most common (60/95) and included 58 strains from CUH. Type I showed a further subdivision into seven subtypes. Type II (23/95) composed of 11 strains from CUH, nine from WUH, three from JNIH and two reference strains. Six type III strains comprised four WUH strains and two JNIH strains. All six strains of type IV were from JNIH. The range of genetic similarity values among V. vulnificus isolates was 0.24 to 1.00. The serotypes of 95 strains were 04 (84.2%), 014 (3.2%), 01 (2.1%), 013 (2.1%), and R (2.1%). The most common 04 serotype strains were distributed among types I (60 strains), II (23 strains), III and IV (six strains). Although the V. vulnificus isolates showed a wide range of genetic similarity values, RAPD analysis could separate V. vulnificus strains into four molecular types, and the isolates from the same hospitals tended to belong to the same molecular type. There was no specific correlation between molecular types and serotypes of V. vulnificus.

Rapid identification of Candida species in blood cultures by a clinically useful PCR method

Widespread use of fluconazole for the prophylaxis and treatment of candidiasis has led to a reduction in the number of cases of candidemia caused by Candida albicans but has also resulted in the emergence of candidemias caused by innately fluconazole-resistant, non-C. albicans Candida species. Given the fulminant and rapidly fatal outcome of acute disseminated candidiasis, rapid identification of newly emerging Candida species in blood culture is critical for the implementation of appropriately targeted antifungal drug therapy. Therefore, we used a PCR-based assay to rapidly identify Candida species from positive blood culture bottles. This assay used fungus-specific, universal primers for DNA amplification and species-specific probes to identify C. albicans, C. krusei, C. parapsilosis, C. tropicalis, or C. glabrata amplicons. It also used a simpler and more rapid (1.5-h) sample preparation technique than those described previously and used detergent, heat, and mechanical breakage to recover Candida species DNA from blood cultures. A simple and rapid (3.5-h) enzyme immunosorbent assay (EIA)-based format was then used for amplicon detection. One hundred fifty blood culture bottles, including 73 positive blood culture bottle sets (aerobic and anaerobic) from 31 patients with candidemia, were tested. The combined PCR and EIA methods (PCR-EIA) correctly identified all Candida species in 73 blood culture bottle sets, including bottles containing bacteria coisolated with yeasts and 3 cultures of samples from patients with mixed candidemias originally identified as single-species infections by routine phenotypic identification methods. Species identification time was reduced from a mean of 3.5 days by routine phenotypic methods to 7 h by the PCR-EIA method. No false-positive results were obtained for patients with bacteremias (n = 18), artificially produced non-Candida fungemias (n = 3), or bottles with no growth (n = 20). Analytical sensitivity was 1 cell per 2-microl sample. This method is simpler and more rapid than previously described molecular identification methods, can identify all five of the most medically important Candida species, and has the potential to be automated for use in the clinical microbiology laboratory.

Aspergillus nidulans infection in a patient with chronic granulomatous disease

Aspergillus nidulans is one of the several species of Aspergillus with low pathogenicity. The significant infections of A. nidulans in human have rarely been reported, almost exclusively in patients with chronic granulomatous disease (CGD). CGD is a primary immunodeficiency disease which results from the absence of the NADPH oxidase in the phagocytic cells, leading to recurrent pyogenic infection and granuloma and abscess formation. Here we report a fatal case A. nidulans infection in a six-year-old boy with chronic granulomatous disease. A. nidulans was isolated from the culture of a paraspinal abscess and Aspergillus was detected in the surgical tissue by in situ hybridization. The patient succumbed despite prolonged treatment with high-dose amphotericin B, itraconazole and interferon-alpha. To our knowledge, this is the first report of A. nidulans infection in Korea.

Eugenol protects neuronal cells from excitotoxic and oxidative injury in primary cortical cultures

We examined the neuroprotective efficacy of eugenol against N-methyl-D-aspartate (NMDA)-, oxygen-glucose deprivation-, and xanthine/xanthine oxidase-induced neurotoxicity in primary murine cortical cultures. Eugenol (100-300 microM) attenuated NMDA (300 microM)-induced acute neurotoxicity by 20-60%. At the same concentration range, eugenol also inhibited NMDA (300 microM)-induced elevation in neuronal 45Ca2+ uptake by 10-30%. In the oxygen-glucose deprivation (50 min) neurotoxicity, eugenol (100-300 microM) prevented acute neuronal swelling and reduced neuronal death by 45-60% in a concentration-dependent fashion. Oxidative neuronal injury induced by xanthine/xanthine oxidase was also significantly reduced (75-90%) by eugenol (100- 300 microM) addition. These results suggest that eugenol may play a protective role against ischemic injury by modulating both NMDA receptor and superoxide radical.

Management of the ventricular shunt in posterior deformities of the skull in craniosynostosis

The existence of an occipitoparietal cerebrospinal fluid shunt complicates the attempt to remodel posterior skull deformities in craniosynostosis. A composite method to reposition the shunt hardware is described and discussed.

Idiopathic granulomatous hepatitis manifested with fever of unknown origin

Idiopathic granulomatous hepatitis is a rare disease of unknown cause that is characterized by recurrent fevers and granuloma in the liver. Attempts to define an exact etiology of the fever of granulomatous hepatitis frequently do not yield a precise diagnosis. Idiopathic granulomatous hepatitis was confirmed after a thorough work up and negative cultures and serologies were obtained, and in the absence of another condition that could lead to granulomas in the liver. We have experienced a 67-year-old female patient who presented with prolonged fever for 2 months and revealed granuloma in liver biopsy. She was treated with glucocorticosteroid and defervescence resulted.

Alternative use of polymerase chain reaction instead of rho-nitro-alpha-acetylamino-beta-hydroxypropiophenone test for the early detection of Mycobacterium tuberculosis in BACTEC 12B cultures

Compared with conventional culture media, the TB BACTEC system has demonstrated improved isolation rates as well as an earlier detection time for mycobacterial species. However, the identification of M. tuberculosis by the rho-nitro-alpha-acetylamino-beta-hydroxypropiophenone (NAP) test in the TB BACTEC 460 system may require 6 days for interpretable results. We evaluated the usefulness of a polymerase chain reaction (PCR) assay for earlier identification of M. tuberculosis in positive BACTEC 12B cultures. A total of 262 TB BACTEC culture specimens with GIs > or = 10 were assayed by PCR, and the results were compared with those of the NAP test. The aliquot from BACTEC 12B vials was boiled for 10 min, and 2 microliters of the boiled suspension was used for the PCR assay. One set of primers based on the IS 6110 sequence of M. tuberculosis was used to amplify a 457 bp fragment of DNA. Of the 173 TB BACTEC culture specimens which were identified as M. tuberculosis by the NAP test. 171 were PCR positive. Of the 21 TB BACTEC cultures identified as MOTT by the NAP test. 19 were PCR negative, but 2 were PCR positive: these two cultures were shown to grow both M. tuberculosis and MOTT in BACTEC 12B vials. Of the remaining 68 cultures which were contaminated with AFB-negative bacteria, the PCR identified M. tuberculosis in 13, in agreement with the NAP results in the reprocessed specimens. Overall, the PCR results in the 262 BACTEC culture specimens with GIs > or = 10 were sensitive in 99.5% (186/187) and specific in 100% (68/68). The mean time for the identification of M. tuberculosis in TB BACTEC cultures with GIs > or = 10 was 7 h by the PCR compared to 5.9 days by the NAP test. These results suggest that the PCR could be used as an alternative to the NAP test for the rapid identification of M. tuberculosis in BACTEC 12B cultures, particularly in those which contained both M. tuberculosis and MOTT or M. tuberculosis and AFB-negative bacteria.

Fast and slow gating types of SR ryanodine receptor/channel purified from canine latissimus dorsi muscle

The ryanodine receptor/channel (RyR) mediates the release of calcium from the sarcoplasmic reticulum (SR) in both skeletal and cardiac muscle cells. There are three isoforms of the RyR: RyR1, RyR2, and RyR3. RyR1 is specifically expressed in skeletal muscles and RyR2 in cardiac muscles. RyR3 is yet another isoform found in non-muscle cells such as neuronal cells. Single channel recordings of RyR1 and RyR2 reconstituted in artificial lipid bilayer show that the characteristics of two isoforms are very distinct. RyR1 has a shorter mean open time and is activated at a higher concentration of Ca2+ than RyR2. In this study, we isolated the heavy SR membranes from canine latissimus dorsi muscles and investigated the single channel activities from the heavy SR membrane fraction using Cs+ as a charge carrier. Two different types of activities were observed. The fast-gating type (FG) with the mean open time of 0.9 ms was more frequently recorded (n = 12) than the slow-gating type (SG) with the mean open time of 269.2 ms. From the I-V relation, the slope conductance of the FG was calculated to be 514.7 pS and the SG, to 625.6 pS. The activity of the fast gating type increased by raising the concentration of Ca2+ in the cis-solution up to 100 microM. The appearance of the SG in the canine heavy SR membrane fraction suggests a possibility that two types of RyR isoform are co-expressed in mammalian skeletal muscle as well as in avian, amphibian and piscine fast twitch muscles.

In vitro differentiation of the murine macrophage cell line BDM-1 into osteoclast-like cells

Osteoclasts are derived from hematopoietic stem cells, but details about their precursor are still obscure. We present here a mouse macrophage cell line, BDM-1 cells, that showed a high potential to differentiate into osteoclast-like multinucleate cells (MNCs) when cocultured with primary osteoblasts for 14 days in the presence of 10(-8) M 1 alpha,25-dihydroxyvitamin D3. These MNCs had tartrate-resistant acid phosphatase (TRAP) activity and strong ability to resorb dentine. In this culture system, 10(-10)-10(-8) M 12-O-tetradecanoylphorbol-13-acetate stimulated the formation of TRAP-positive MNCs, whereas salmon calcitonin inhibited it. Time-course effect studies showed that 12-O-tetradecanoylphorbol-13-acetate had an effect on the late phase of osteoclast differentiation but not on precursor proliferation. By immunocytochemical staining, all BDM-1 cells expressed Mac-1, Mac-2, and MOMA-2 antigens, and a large number of them expressed F4/80 antigen, but the rest of them were negative for this antigen. To select subclones able to differentiate into TRAP-positive MNCs, we sought to isolate several subclones from BDM-1 cells by mean of different specificity for F4/80 antigen expression. TRAP-positive MNCs were not generated from F4/80-positive subclones, but were obtained from subclones containing F4/80-negative cells. These results suggest that an F4/80-negative macrophage subpopulation is responsible for the differentiation of this cell line into osteoclasts.

Vascular lesions of the cranial base

Vascular lesions can be classified broadly into two groups on the basis of cellular proliferation characteristics: hemangiomas and vascular malformations. Additional lesions include a heterogeneous group of vascular tumors such as those represented by hemangiopericytoma and those with a frankly malignant course. Those lesions located around the cranial base remain challenging and difficult clinical problems. The care of patients with these problems is complex; it frequently will need a full spectrum of individuals from many disciplines involved in many diverse aspects of management: medical, radiologic, anesthetic, and surgical. Fortunately, advances in science and technology have markedly expanded our capability in treating these patients and have allowed us increasing safety and ease in dealing with previously untreatable and unresectable lesions.

Correlation between blood pressure changes assessed by 24-hour ambulatory blood pressure monitoring and urine microalbuminuria excretion rate in normal and essential hypertension

To document the correlation between renal damage and circadian blood pressure variation, urinary microalbumin excretion rate (UAER) and 24-hour ambulatory blood pressure monitoring (24-hr ABPM) were performed in 16 normotensives and 29 stage I-III essential hypertensive subjects (whole-day mean BP; 120.13/79.06 mmHg vs 152.59/94.31 mmHg, p < 0.05). The BP variables of 24-hr ABPM included hourly mean arterial pressure (MAP), maximum, minimum and mean systolic and diastolic BP of the awaking (daytime) and sleep time (nighttime), and whole-day mean BP. Subsequently, BP reduction of maximum, minimum and mean BP between awaking time and sleep time were also calculated as other variables. UAER was not different between the normotensive and hypertensive group (9.44 +/- 11.48 vs 11.87 +/- 9.27 micrograms/min, p > 0.05). 10 subjects (2/16 in normal vs 8/29 subjects in hypertensives) revealed over 16 micrograms/min of UAER. All of the awaking BP variables and whole-day mean BP were correlated with the UAER in whole subjects and hypertensives, but almost sleep BP variables except maximum DBP and mean DBP were not. On the contrary, only daytime minimum DBP and SBP were correlated with UAER in normotensives. The common best correlated BP variable in awaking time was minimum BP (DBP and SBP; r = 0.49, r = 0.44 in whole, r = 0.51, r = 0.58 in hypertensives, r = 0.54, 0.56 in normotensives, all p < 0.05). Hourly MAP at 24 PM in whole subjects (r = 0.49, p < 0.05) and that of at 22 PM in hypertensives were best correlated (r = 0.71, p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Induction of mononuclear precursor cells with osteoclastic phenotypes in a rat bone marrow culture system depleted of stromal cells

The importance of bone stromal cell involvement in osteoclast differentiation has been suggested. However, the detailed mechanism of its regulation is unclear. We investigated whether the soluble factors from osteoblastic cells influence osteoclast lineage cells in a population of rat bone marrow cells depleted of stromal cells. We show here that hematopoietic progenitor cells differentiate into mononuclear precursor cells, the preosteoclasts, that strongly express certain osteoclastic phenotypes in the absence of stromal cells. The multinucleation of the preosteoclasts occurred only in the presence of 1,25 dihydroxyvitamin D3 and stromal cells. The preosteoclasts themselves did not have dentine-resorbing activity, but they could differentiate into multinucleate osteoclast-like cells having such activity in the presence of rat primary osteoblasts. This culture system is a unique differentiation system for preosteoclast induction.

Harvey Cushing: first guest at "The Divine Banquet of the Brayne"

Harvey Cushing will remain forever ensconced in surgical memory as the visionary who established contemporary neurosurgery. Raised in Cleveland in a middle-class family with a medical background, he gave little indication early of his later prowess. A college education at Yale University yielded a modest performance, although he showed somewhat better promise as a medical student at Harvard University. During his surgical training at the Johns Hopkins Medical School, he emerged as a bright, industrious young man with a glint of steel to his intellect. From Halsted he learned the academic basis of surgery and the meticulousness necessary for technical success. Osler became his friend and provided him with a foundation in the history of medicine and the recognition of its importance in shaping the future. The decision to spend a year in Europe visiting clinics and renowned surgeons may have laid the foundations for the subsequent configuration of his career. In Britain he saw firsthand the glorious museums and libraries of the Hunters and the legacy that their schools of surgery had endowed to the nation. In Paris and London he mixed with the surgical aristocracy of the times and learned the power of societies and the traditions of their patrons. In Berne he was exposed to the surgical purity and physiologic expertise of Kocher, supported by the estimable scientific practice of Kroneker. As an "arbeid," Kocher posed him the problem of establishing the mechanism of the regulation of cerebral perfusion. This question, which he so rapidly and successfully unraveled, probably played a large part in igniting his enthusiasm toward the study of the brain as a future career. In his travels he encountered diverse intellects and experienced a wide panoply of European medical thought. He conversed widely at both a social and professional level and integrated all information into meticulously kept diaries that served as not only a record but also a template from which later plans were derived. A final 6-week sojourn in Liverpool working on the primate cortex with Sherrington, the greatest neurophysiologist of that time, may have sealed his decision to turn his initial project with Kocher into the opus of a lifetime. The 14-month tour of Europe transformed Cushing from a relative unsophisticate into a figure of giant proportions. All that he experienced became part of his life and was integrated into his subsequent career.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of problem-based, self-directed undergraduate education on life-long learning

OBJECTIVE

To compare how well graduates of a self-directed, problem-based undergraduate curriculum (at McMaster University [MU], Hamilton, Ont.) and those of a traditional curriculum (at the University of Toronto [UT]) who go on to primary care careers keep up to date with current clinical practice guidelines.

DESIGN

Analytic survey. Management of hypertension was chosen as an appropriate topic to assess guideline adherence. An updated version of a previously validated questionnaire was mailed to the participants for self-completion.

SETTING

Private primary care practices in southern Ontario.

PARTICIPANTS

A random sample of 48 MU graduates and 48 UT graduates, stratified for year of graduation (1974 to 1985) and sex, who were in family or general practice in Ontario; 87% of the eligible subjects in each group responded.

MAIN OUTCOME MEASURES

Overall and component-specific scores; analysis was blind to study group.

RESULTS

The overall mean scores were 56 (68%) of a possible 82 for the MU graduates and 51 (62%) for the UT graduates (difference between the means 5, 95% confidence interval 1.9 to 8.2; p < 0.01). Multivariate linear regression analysis of seven factors that might affect questionnaire scores revealed that only the medical school was statistically significant (p < 0.01). The MU graduates had significantly higher mean scores than the UT graduates for two components of the questionnaire: knowledge of recommended blood pressures for treatment (p < 0.05) and successful approaches to enhance compliance (p < 0.005). The trends were similar for the other components but but were not significant.

CONCLUSIONS

The graduates of a problem-based, self-directed undergraduate curriculum are more up to date in knowledge of the management of hypertension than graduates of a traditional curriculum.

Subtle gastric abnormalities in a canine model: detection with low-dose imaging with storage phosphors and its equivalence to conventional radiography

The authors compared low-dose (32% of standard exposure) storage phosphor digital imaging (system resolution: 0.2-mm pixels, 10 bits) with isovoltage 75-kVp conventional radiography (standard exposure) in the detection of subtle simulated gastric abnormalities by using air contrast barium studies. Subtle simulated abnormalities (3-7-mm polyps, 4-15-mm ulcer craters, 4-11-mm-diameter edema, and 11-12-mm linear ulcers) were produced in resected canine stomachs. Receiver operating characteristic analysis of 1,800 observations by six readers indicated that the digital images with and without high-frequency edge enhancement were equivalent to conventional radiographs (mean receiver operating characteristic areas [+/- standard deviation]: 0.76 +/- 0.06, 0.78 +/- 0.04, and 0.77 +/- 0.04, respectively). The accuracy of the diagnosis was equivalent for all three modalities. The following mean accuracies of negative and positive responses, respectively, for unenhanced digital, edge-enhanced digital, and conventional images were determined: 0.71 +/- 0.05 and 0.41 +/- 0.07, 0.71 +/- 0.04 and 0.51 +/- 0.09, and 0.68 +/- 0.04 and 0.43 +/- 0.05. It was concluded that low-dose storage phosphor air-contrast barium studies were equivalent to conventional radiography in the detection of subtle gastric abnormalities.

Purification of the lysosomal acid lipase from human liver and its role in lysosomal lipid hydrolysis

The lysosomal acid lipase has been purified 2,500-fold to near homogeneity from human liver. The enzyme was converted to a soluble form by extraction of frozen tissue with Triton X-100. The enzyme, which required Triton X-100 in buffers at all purification steps for optimal yields, was stabilized by the inclusion of 33% ethylene glycol during purification. Lectin chromatography on concanavalin A-Sepharose followed by chromatography on carboxymethyl-cellulose and Sephadex G-150 provided the highly purified enzyme in 17% yield. Sodium dodecyl sulfate-acrylamide gel electrophoresis indicated that the minimum molecular weight was about 29,000 +/- 1,000. Minor protein contaminants at Mr = 58,500, 14,700 and 13,900 were present in the final preparation. A single protein band, with enzyme activity, was observed in nondenaturing acrylamide gels containing Triton X-100. Gel filtration on Sephadex G-150 in the presence of Triton X-100 gave an apparent molecular weight of about 125,000 +/- 13,000. Trioleoylglycerol, cholesterol oleate, and 1,2- and 1,3-dioleoylglycerols were substrates for the purified enzyme giving apparent Vmax values of 5,400, 1,400, 19,400, and 22,100 nmol min-1 mg of protein-1, respectively, and Km values of 0.8, 0.8, 0.9, and 1.2 mM, respectively. The recoveries of both trioleoylglycerol and cholesterol oleate hydrolytic activities were nearly identical at each purification step, suggesting that the acid lipase as single enzyme is responsible for lysosomal hydrolysis of the neutral lipids. Monooleoylglycerols were not substrates for the enzyme.

Separation and characterization of the acid lipase and neutral esterases from human liver

Electrophoresis of human liver homogenates followed by reaction with 4-methylumbelliferyl palmitate reveals the presence of two major electrophoretic forms with esterase (lipase) activity toward this substrate. The two enzymes were isolated and partially purified based on their solubility differences and their relative affinities for the lectin column concanavalin A-Sepharose 4B. Lipase A was particulate with an acidic pH optimum (5.2) and could be solubilized with the non-ionic surfactant Triton X-100. Lipase B was soluble and had a more neutral pH optimum (6.3--6.6). Both forms bound to immobilized concanavalin A and could be specifically eluted. Buffers containing alpha-methylmannoside eluted lipase B, and buffers with alpha-methylmannoside and Triton X-100 eluted lipase A, giving a 22- and 257-fold purification, respectively, over whole-tissue homogenates. Cholesterol oleate, trioleoylglycerol, and 4-methylumbelliferyl palmitate were substrates for solubilized lipase A. Lipase B hydrolyzed 4-methylum-belliferyl palmitate but not trioleoylglycerol or cholesterol oleate. Lipase B was more thermolabile than lipase A, and it was selectively inhibited by diethyl-p-nitrophenyl phosphate at low concentrations. We conclude that lipase A and B are distinctly different enzymes and that they are probably not related polymorphic forms of one another.