Bile medium for rapid presumptive identification of group B streptococci

A bile medium was developed for rapid presumptive identification of beta hemolytic group B streptococci. Of 131 clinical isolates of group B streptococci, 125 (95.4%) yielded positive reaction within 6 h incubation. No false positive reaction was found in 134 clinical isolates of groups A, C, F, and G beta-hemolytic streptococci. The sensitivities of the bile medium, rapid hippurate hydrolysis and modified LAL-1 medium were 95.4, 98.5 and 93.1%, respectively. All three media showed 100% specificity. Therefore, the bile medium provides as an additional medium for rapid presumptive identification of group B streptococci.

Contralateral temperature changes of the finger surface during video endoscopic sympathectomy for palmar hyperhidrosis

One hundred and eight consecutive patients with primary palmar hyperhidrosis were surgically managed by coagulation of bilateral T2 sympathetic ganglia using video thoracoscopic techniques. Patients were divided into two groups. In the first group (N = 46), finger surface temperature of the ipsilateral index finger was recorded before and after T2 ganglionectomy. The average increase of post-operative temperature was 2.74 +/- 0.27 degrees C (mean +/- SE) on the right side and 2.67 +/- 0.33 degrees C on the left (P < 0.05). The significant rise of temperature resulting from sympatholytic vasodilatation was only noted in cases of exact ablation of the T2 ganglion. In the second group (N = 62), surface temperatures of both index fingers were monitored and recorded simultaneously. These patients were arbitrarily subdivided into Group 2-A (N = 29) when right side ganglionectomy was performed first and Group 2-B (N = 33) when left side ganglionectomy was done initially. After the first ganglionectomy was completed, an ipsilateral increase with a contralateral decrease of temperature was observed; the average increase of temperature was 1.92 +/- 0.35 degrees C and 2.19 +/- 0.30 degrees C, and the average decrease was 1.50 +/- 0.51 degrees C and 1.67 +/- 0.39 degrees C for Group 2-A and 2-B respectively (P < 0.05). The authors postulate that a cross-inhibitory effect by the post-ganglionic neurons innervating blood vessels of the upper extremities may exists in humans and this effect is released after ganglionectomy, resulting in contralateral vasoconstriction and decrease of finger surface temperature.

Adaptations of ligamentum teres in ischemic necrosis of human femoral head

Little is known about the biomechanical properties of human ligamentum teres. To more fully understand the ligamentum teres, its dimensions and mechanical properties were measured in 22 cases of acute fracture of the femoral neck and 21 cases of ischemic necrosis of the femoral head. The specimens first were preconditioned and then loaded to failure with a testing machine at a fast strain rate of 100% s(-1). The ischemic necrosis group had a significantly larger volume (3.09 +/- 1.81 ml versus 1.30 +/- 0.62 ml) and cross section area (65.3 +/- 59.1 mm2 versus 30.6 +/- 27.2 mm2) than did the acute fracture group. The former also had a significantly greater ultimate load (234 +/- 168 N versus 130 +/- 111 N) and strain energy to failure (1.22 +/- 1.04 J versus 0.41 +/- 0.39 J), but a significantly smaller linear modulus (4.72 +/- 3.31 MPa versus 8.69 +/- 7.97 MPa) than did the latter. Histologic studies showed differences in the amount of organized collagen and components of subsynovial tissue between the 2 groups. Mechanical and morphologic adaptations of the ligamentum teres in a group of ischemic femoral heads are described, and a possible biomechanical role is suggested for the ligamentum teres in the hip joint in conjunction with the ischemic necrosis of the femoral head.

Microbiologic assay for detection of antimicrobial agents in urine

Antimicrobial therapy can be a confounding factor in the diagnosis of urinary tract infection and is not always reported to laboratories by physicians. We developed a microbiologic assay for screening urine specimens for antimicrobial agents. Bacillus stearothermophilus was used as the indicator bacteria. A total of 1,921 urine specimens from three hospitals in Taiwan were screened using this assay. Of the samples assayed, 1,293 were positive for antimicrobial agents. Agreement between information provided by physicians and laboratory findings was 68.5% (419/612). In the presence of antimicrobial agents in the urine samples, the isolation of yeasts and Pseudomonas aeruginosa increased dramatically, from 4.5 to 19.5% and 4.2 to 13.2%, respectively. Additionally, Escherichia coli was more resistant to gentamicin (75.3% vs 48.7%, p < 0.0001), norfloxacin (85.2% vs 64.6%, p = 0.0006) and co-trimoxazole (58.5% vs 35.5%, p = 0.0018). In view of the high rate of occurrence of antimicrobial agents in urine specimens and the lack of information provided by most physicians to laboratories, a screening method to detect the presence (or absence) of antimicrobials in urine specimens may be a useful tool particularly in areas such as Taiwan where antimicrobial agents are commonly abused.

Heritability estimate of hypertrophic cardiomyopathy in pigs (Sus scrofa domestica)

The purpose of this study was to evaluate the heritability of hypertrophic cardiomyopathy (HCM) in pigs and the relation between HCM and heart measurements, pathologic features, and growth to provide references for HCM line development. A total of 353 on-farm tested gilts (females) and boars (males) from 74 sire families were randomly selected from a single breeding farm where HCM was prevalent. Hearts were collected after animals were slaughtered. Heart length, width, and weight, heart-to-body weight ratio, and thickness of the cranial, middle, and caudal portions of the ventricular septum, left and right ventricles, and apex were measured. Cardiac hypertrophy and myocyte disorganization, myocardial and endocardial fibrosis, and intramural coronary arterial occlusion were used as criteria for HCM. Growth traits were evaluated from average daily body weight gain, ultrasonically determined backfat thickness, loin-eye area, and performance selection index. Heritability of the disease was estimated by treating it as a threshold trait. The prevalence of HCM in three studied breeds was 5.26 in Duroc, 22.98 in Landrace, and 5.56% in Yorkshire pigs. The value in Landrace pigs was significantly (P < 0.001) higher than that in the other pigs. There was no significant difference between sexes. In general the heart of pigs with HCM was heavier, wider, longer, and thicker than that of clinically normal pigs. Backfat was the only growth trait with a difference (P < 0.05) among pig breeds. The HCM pigs were leaner than normal pigs. Leaner pigs may have a higher risk of HCM. Heritability of HCM was > 0.30 for all three breeds, but the standard errors of these estimates were high because of limited sample size, in particular for the Yorkshire and Duroc breeds. The preliminary results of this study indicate that HCM in pigs is moderately heritable; thus development of a high-HCM incidence line by selection is possible.

Patellar dislocation after total knee arthroplasty

BACKGROUND

Patellar problem is an important cause of nonseptic failure of the current condylar design of total knee arthroplasties. Patellar dislocation after total knee arthroplasty is infrequent but can cause disabling symptoms.

METHODS

From March, '84 to July, '92, 1652 total knee arthroplasties were performed at this Hospital. Of these 1100 knees in 978 patients were available to be followed up regularly at the Outpatient Department. Eleven cases of patellar dislocation after total knee arthroplasty were encountered during follow-up. Among these patients, nine patients had received operation at this Hospital; the other two patients had been referred here by the other hospitals. All 11 patients had been treated with surgical methods: proximal realignment of the quadriceps alone in 6 knees, lateral retinacular release combined with revision of the malaligned components in 2 knees, combined proximal and distal realignment in 2 knees and patellar tendon transfer in 1 knee.

RESULTS

After an average follow-up of 21.8 months, from April, '84 to April, '93, there was one redislocation, unfortunately caused by trauma. Using the average knee rating scale of the Hospital for Special Surgery, New York, USA, the results of 90.5 were satisfactory and encouraging.

CONCLUSIONS

Patellar dislocation after total knee arthroplasty can cause disabling symptoms, including pain, weakness, limited range of motion, extension lag and difficulty when climbing up or down stairs. The cause of patellar dislocation after total knee arthroplasty was error in surgical technique in this series. Revision of the component should be performed in those with malaligned component. Proximal realignment is recommended in those with quadriceps imbalance. Distal realignment is recommended only when proximal realignment alone has failed to restore proper patellar tracking, this should be carried out with great caution due to the potential for serious complications.

Invasive Streptococcus pneumoniae infection associated with rapidly fatal outcome in Taiwan

We observed 42 cases of invasive Streptococcus pneumoniae infections from 1991 through 1993 in southern Taiwan. The antimicrobial susceptibilities and distribution of serotypes of the 42 isolates from these invasive infections were determined. Serotypes 14, 3, 6, 23, 15 and 4 were most commonly identified. Serotypes 14 and 6 most frequently caused infections in pediatric patients, while serotypes 3, 14 and 23 were commonly encountered in adults. Overall, 85.7% of the isolates were included in the serotypes represented in the 23-valent pneumococcal vaccine. Three isolates were intermediately resistant to penicillin and none were fully resistant. Resistance rates were: erythromycin, 61.9%; clindamycin, 47.6%; chloramphenicol, 19%; and tetracycline, 73.8%. Resistance to three or more classes of antibiotics was found in 33.3% of the isolates, in which the majority were serotypes 14 and 6 and nontypeable isolates. Bacteremic pneumonia and primary bacteremia accounted for 64.3% of the infections. Mortality was 42.6%. Factors associated with higher mortality included age of > 16 years, the presence of underlying diseases, development of one or more septic complications, bacteremic pneumonia and the presence of serotype 3 isolates. Rapidly fatal outcome (the illness developed less than 48 hours prior to admission and the death occurred within 48 hours of hospitalization) occurred in 12 (66.7%) of the 18 patients who died. All these patients received adequate antibiotic treatment and aggressive intensive care, indicating the fulminant nature of this infection. Mucoid serotype 3 isolates caused rapidly fatal outcomes. Given the severity of these infections despite adequate antibiotic therapy and the vulnerability of patients with altered immune responses, there is a dire need for introduction of new therapeutic options and preventive measures to prevent mortality due to invasive S. pneumoniae infections.

Collagen type IX from human cartilage: a structural profile of intermolecular cross-linking sites

Type IX collagen, a quantitatively minor collagenous component of cartilage, is known to be associated with and covalently cross-linked to type II collagen fibrils in chick and bovine cartilage. Type IX collagen molecules have also been shown to form covalent cross-links with each other in bovine cartilage. In the present study we demonstrate by structural analysis and location of cross-linking sites that, in human cartilage, type IX collagen is covalently cross-linked to type II collagen and to other molecules of type IX collagen. We also present evidence that, if the proteoglycan form of type IX collagen is present in human cartilage, it can only be a minor component of the matrix, similar to findings with bovine cartilage.

Shoulder instability in athletes. The Asian perspective

Recently, there has been an upsurge of interest among the orthopaedic sports medicine community in Asia on this subject of athletic shoulder instability. This is particularly prominent in countries such as Japan, Korea, Taiwan, and Hong Kong, where sports requiring throwing and overhead use of the upper limb are popular. In this review, the classification of the condition is analyzed with a specific account of the rotator interval injury. A systematic plan of clinical assessment is presented highlighting the specific regional considerations in clinical practice and cost-effectiveness of the health care systems in Asia. The management of athletic shoulder instability depends on patient attitude and cultural background. In Asia, the popular choice of Bankart repair with capsular shift procedure is presented with special reference to the unique experience of multidirectional and habitual posterior instability. Arthroscopic surgery is becoming popular in Asia, and the indications and limitations of the technique in the management of shoulder instability are discussed.

Percutaneous transvenous mitral commissurotomy in patients with mitral stenosis and coexistent hyperthyroidism

Percutaneous transvenous mitral commissurotomy (PTMC) was performed successfully without complications in 3 patients with severe mitral stenosis and hyperthyroidism. All 3 patients had pliable, noncalcified mitral valves. One patient who had been treated with methimazole for 6 months was still in a hyperthyroid state when she presented with intractable congestive heart failure and was found to have severe mitral stenosis. The heart failure improved immediately after PTMC, but the patient remained in New York Heart Association functional class 2 until a euthyroid state was achieved with I131 therapy. In the other 2 patients, hyperthyroidism was unsuspected at the time of PTMC. Unexpectedly suboptimal symptom improvement led to the diagnosis of hyperthyroidism 1 month after the intervention. In all 3 patients, PTMC resulted in an immediate hemodynamic and clinical improvement. However, complete clinical improvement occurred only when euthyroid state was achieved after antithyroid treatment. The present study suggests that PTMC is a safe and effective intervention modality in patients with coexisting hyperthyroidism and severe mitral stenosis. The procedure may be considered a therapeutic option in patients with hyperthyroidism and severe mitral stenosis.

Antimicrobial resistance and serotype distribution of Streptococcus pneumoniae strains isolated in southern Taiwan

The antimicrobial susceptibilities and serotypes of 115 Streptococcus pneumonia strains isolated in southern Taiwan from January 1990 to December 1993 were determined. All isolates were susceptible to cephalothin, cefotaxime, trimethoprim/sulfamethoxazole and vancomycin, and 14 of the isolates were resistant to penicillin G. The oxacillin disk method for presumptive detection of resistance to penicillin had a sensitivity of 85.7% and specificity of 97.0%. Resistance rates were as follows: erythromycin 62.2%, tetracycline 71.3%, clindamycin 46.1% and chloramphenicol 19.1%. Eighty-four percent of the isolates were resistant to one or more of the antibiotic tested. Multiple resistance (to three or more classes of antibiotics) was identified in 40.9% of all the isolates and 100% of penicillin-resistant isolates. The predominant serotypes were: 14 (19.1%), 3 (17.4%), 23 (15.7%), 6 (10.4%), and 15 (6.1%). Serotypes 14 and 63 most commonly caused childhood infections, while serotypes 3 and 23 were frequently encountered in adults. The proportion of coverage in 23-valent pneumococcal polysaccharide vaccine was 92.2%, if vaccine-related serotypes were considered to be cross-protecting. Seven (58%) of 12 typable penicillin-resistant isolates belonged to serotype 23 and two (16.7%) to serotype 6. All isolates of serotype 14, 23, 15 and 19 were resistant to one or more antibiotics. Multiple drug resistance was frequently associated with serotype 23 (31.9%), 14 (23.4%) and 6 (17.0%). Sixty-five percent of isolates of serotype 3 were susceptible to all antibiotics tested. The high level of antimicrobial resistance in S. pneumoniae mandates the continuous surveillance of resistance and the strict control of antibiotic use in Taiwan.

Lipid peroxidation in preeclamptic and eclamptic pregnancies

Preeclampsia and eclampsia remain one of the most serious complications of pregnancy, and the pathophysiology of the diseases is not fully understood. To investigate lipid peroxidation status in preeclamptic and eclamptic pregnancies, we measured the serum malondialdehyde (MDA) level, a product of lipid peroxide, in pregnant women with or without preeclampsia or eclampsia. Serum MDA levels were raised in women with preeclamptic (4.5 +/- 0.6 mumol/L) (P < 0.005) or eclamptic (4.9 +/- 0.8 mumol/L) (P < 0.005) pregnancies compared with uncomplicated pregnancy (3.3 +/- 0.7 mumol/L). An increased MDA level was also present in uncomplicated pregnancy compared to non-pregnant women (2.6 +/- 0.4 mumol/L) (P < 0.05). Serum MDA levels were significantly decreased at the third day post-delivery in either uncomplicated pregnancy (P < 0.05), preeclamptic pregnancy (P < 0.005) or eclamptic pregnancy (P < 0.005). A positive correlation was seen between MDA level and both systolic and diastolic blood pressure in preeclamptic and eclamptic pregnancies. These results provide further evidence that excessive lipid peroxidation may contribute to the pathophysiology and pathogenesis of preeclamptic and eclamptic pregnancies.

Early repair of traumatic ventricular septal defect and mitral valve regurgitation

Traumatic ventricular septal defect with valvular injury is an uncommon blunt trauma. It may develop either immediately or be delayed, but it should be corrected electively. With hemodynamic instability and cardiopulmonary deterioration, however, early repair is necessary as a lifesaving procedure. Two-dimensional echocardiography and Doppler color flow mapping are very important for rapid detection in patients who are critically injured. This is a case report of the successful repair of ventricular septal defect and posterior leaflet disruption of mitral valve right after blunt trauma.

Decreased activity of erythromycin against Streptococcus pyogenes in Taiwan

A total of 78 clinical isolates of Streptococcus pyogenes were collected from January 1992 through December 1993 from patients in southern Taiwan. The in vitro activities of 10 antimicrobial agents were determined by the agar dilution method. Penicillin, cephalothin, cefotaxime, vancomycin, and ofloxacin were shown to be active against S. pyogenes isolates, with MICs at which 90% of isolates are inhibited (MIC90s) being < or = 0.03, < or = 0.13, < or = 0.13, < or = 0.13, and < or = 0.25 microgram/ml, respectively. Erythromycin and azithromycin both had poor activities (MIC50s, 16 and >128 micrograms/ml, respectively; MIC90s, >128 and >128 micrograms/ml, respectively). The activities of tetracycline, clindamycin, and chloramphenicol against a significant number of these isolates were also limited. As the MICs of clindamycin and chloramphenicol for the isolates increased, the MICs of the two macrolides also increased. Clindamycin, chloramphenicol, and the two macrolides were less potent against isolates recovered form throat swab samples than against those from blood or other sources. Isolates of the T12 and T1 serotypes accounted for 53.8% of all isolates. The majority (87.5%) of the isolates recovered from throat swab samples were of the T12 serotype, whereas 19.2% of the isolates recovered from blood were of the T12 serotype. In contrast, 66.7% of the isolates of the T1 serotype were derived from blood but none were derived from throat swab samples. Of the 33 T12 serotype isolates, erythromycin MICs for 78.8% of the isolates were >128 micrograms/ml. Because of the poor activities of erythromycin and azithromycin against S. pyogenes isolates from patients in southern Taiwan, these drugs should no longer be considered the drugs of choice for the management of group A streptococcal infections among patients who live in this area.

Structural analysis of cross-linking domains in cartilage type XI collagen. Insights on polymeric assembly

The collagen framework of hyaline cartilage is based on copolymers of types II, IX, and XI collagens. Previous studies have established specific covalent interactions between types II and IX collagens. The present study examined cross-linking sites in type XI collagen to define better the full heteropolymeric assembly. Pepsinsolubilized type XI collagen was purified from fetal bovine cartilage. The cross-linking amino acids in the preparation were primarily divalent, borohydride-reducible structures; pyridinoline residues were essentially absent. Individual alpha 1(XI), alpha 2(XI), and alpha 3(XI) chains were resolved by high performance liquid chromatography. Telopeptides still attached by cross-links to helical sites were released by periodate oxidation and identified by microsequencing. Analysis of cross-linked peptides isolated from trypsin digest of each alpha-chain identified the attachment helical sites for the telopeptides. A high degree of interchain specificity was evident in the cross-linking between N-telopeptides and the COOH terminus of the triple-helix, consistent with a head-to-tail interaction of molecules staggered by 4D (D = 67 nm) periods. In addition, alpha 1(II) C-telopeptide was linked to the amino-terminal site of the alpha 1(XI) triple helix. In summary, the results show that type XI collagen molecules are primarily cross-linked to each other in cartilage, implying that a homopolymer is initially formed. Links to type II collagen are also indicated, consistent with an eventual cofibrillar assembly. Analysis of cartilage extracts showed that all three chains, alpha 1(XI), alpha 2(XI), and alpha 3(XI), had at least in part retained their N-propeptides in cartilage matrix and that the alpha 3 (XI) chain was the IIB splicing variant product of the COL2A1 gene. Of particular note was the finding that the N-telopeptide cross-linking site in both alpha 1(XI) and alpha 2(XI) is located amino-terminal to the putative N-propeptidase cleavage site. This structural feature provides a potential mechanism for the proteolytic depolymerization of type XI collagen by proteases that can cleave between the cross-link and the triple helix (e.g. stromelysin).

Evaluation of four commercial rapid diagnostic kits for identifying Staphylococcus aureus

Three rapid latex agglutination kits (Aureus Test, Pastorex Staph-Plus, and StaphAurex) and one hemagglutination test kit (SlidexStaph) were compared with the conventional coagulase test for the identification of Staphyloccus aureus. A total of 192 methicillin-resistant S. aureus (MRSA), 75 methicillin-susceptible S. aureus (MSSA) and 86 coagulase-negative staphylococci and Micrococcus spp. were tested. The sensitivities of Aureus Test, Pastorex Staph-Plus, StaphAurex and SlidexStaph were 98.6, 99.4, 90.8 and 97.3%, respectively. Capsular serotypes of 27 strains of MRSA were also determined, in which 15 (55.6%) were capsular serotype 5, 11 (40.7%) were capsular serotype 8, and 1 (3.7%) was nontypeable. All the commercial agglutination kits showed 100% specificity except StaphAurex which had a specificity of only 96.5%. False-positive reactions were found in the strains of S. hominis, S. warneri and unidentified coagulase-negative staphylococci. These results suggest that Aureus Test, Pastorex Staph-Plus, and SlidexStaph are better than StaphAurex for rapid identification of S. aureus.

Purification of a variant-specific surface protein of Giardia lamblia and characterization of its metal-binding properties

Giardia lamblia, an intestinal parasite of humans and other vertebrates, undergoes surface antigenic variation by modulating the expression of different variant-specific surface proteins (VSP). VSPs are cysteine-rich surface proteins that bind zinc and other heavy metals in vitro. We developed an immunoaffinity chromatographic method to purify a VSP in order to determine its biochemical properties. The sequences of two different proteolytic fragments agreed with the sequence deduced from the cloned gene, and amino-terminal sequence indicated the removal of a 14-residue signal peptide, consistent with the transport of VSP to the cell surface. The protein is not glycosylated and has an isoelectric point of 5.3. X-ray microanalyses indicated that the major metals in Giardia trophozoites, as well as purified VSP, are zinc and iron. The zinc concentration in Giardia cells was found to be 0.43 mM and the iron concentration 0.80 mM when compared with standard samples (zinc) or calculated from a known physical constants (iron). We propose that metal coordination stabilizes VSPs, rendering them resistant to proteolytic attack in the upper small intestine. Moreover, the ability to bind ions by Giardia may play a role in nutritional deficiency and/or malabsorption in heavily infected persons.

Wrist injuries in adolescent gymnasts of a Chinese opera school: radiographic survey

PURPOSE

To determine the prevalence of chronic wrist injuries among adolescent gymnasts and the consequences of repetitive stress.

MATERIALS AND METHODS

Students of a Chinese opera school underwent radiography of both wrists and answered a questionnaire. They were separated into study (n = 261) and control (n = 63) groups according to participation in or abstinence from exercise training, respectively. They were further separated into fused and unfused physis subgroups. The ulnar variance was measured on posteroanterior radiographs. Abnormalities of distal radii were investigated.

RESULTS

An increase in both mean ulnar variance and frequency of ulnar-plus variance was noted in the study subgroups. Fourteen (8.2%) of 170 wrists of the fused physis study subgroup had an exceedingly large ulnar-plus variance. Sixty-one (17.3%) of 352 wrists had abnormal morphology of the distal radii in the unfused physis study subgroup. Widening of the physis was the most common finding.

CONCLUSION

Chronic, repetitive stress in the wrists of adolescent gymnasts results in a localized growth disturbance of the distal radius with resultant ulnar-plus variance. Stress injuries of the physis may lead to permanent sequelae, even in asymptomatic individuals.

Chronically stressed wrists in adolescent gymnasts: MR imaging appearance

PURPOSE

To investigate the magnetic resonance (MR) imaging appearance of a chronically stressed wrist and to assess the utility of MR imaging for evaluation of injuries to the growth plate.

MATERIALS AND METHODS

Coronal T1-weighted spin-echo and gradient-echo MR images were obtained of 93 wrists in 47 high-risk gymnasts of a Chinese opera school. MR imaging and radiographic findings were correlated in 93 wrists.

RESULTS

The major MR imaging abnormalities of 47 radii with abnormal radiographic findings were horizontal fractures (n = 23), physeal cartilage extension to metaphysis (n = 17), and physeal widening (n = 17). The major MR abnormalities of 46 radii with normal radiographs included physeal cartilage extension (n = 12), metaphyseal bone bruise (n = 8), and vertical fractures (n = 4).

CONCLUSION

Physeal cartilage extension into the metaphysis represents a healing sign in chronically stressed adolescent wrists. MR imaging findings including horizontal fracture and physeal cartilage extension to the metaphysis suggest that physeal widening occurred secondary to metaphyseal injury.

The efficacy of postprostatectomy radiotherapy in patients with an isolated elevation of serum prostate-specific antigen

PURPOSE

To determine the efficacy of radiotherapy (RT) in patients with an isolated elevation of prostate specific antigen (PSA) after radical prostatectomy (RP).

METHODS AND MATERIALS

Between November 1987 and May 1993, 53 patients with adenocarcinoma of the prostate were referred for pelvic RT for an elevated PSA after RP. No patient had clinically or radiographically apparent local or distant disease, nor had an undergone prior androgen ablation. Patients received a median dose of 61.2 Gy to the prostatic bed. An undetectable PSA was required to be considered disease free (NED). Univariate and multivariate analyses were performed to identify factors predictive of becoming disease free after RT.

RESULTS

The median follow-up was 15 months. Of the 53 patients, 16 (30%) became NED after RT and 15 (28%) had a declining (n = 11) or stable (n = 4) PSA at last evaluation. The median time after RT to achieve an undetectable PSA was 9.3 months. At 12 and 24 months, the actuarial disease-free survival was 30 and 23%, respectively; actuarial progression-free survival was 71 and 26%, respectively. By univariate analysis, the last PSA level before RT (i.e., the pre-RT PSA) and an undetectable PSA after RP were significant predictors of becoming NED (p = 0.0001 and 0.04, respectively). However, on multivariate analysis, only the pre-RT PSA remained significant (p = 0.01). The mean pre-RT PSA differed significantly between patients who became NED after RT and those who did not (1.5 +/- 0.2 ng/ml vs. 7.6 +/- 1.6 ng/ml, respectively; p = 0.018). Fourteen of 27 (52%) patients with pre-RT PSA levels < or = 2.5 ng/ml became NED, vs. only 2 of 26 (8%) patients with higher levels. There were no severe acute or late sequelae of RT.

CONCLUSION

Prostatic-bed RT for an elevated serum PSA after RP is most effective in patients with a pre-RT PSA < or = 2.5 ng/ml. Patients with significantly higher PSA values are unlikely to benefit from RT, possibly due to the presence of occult distant metastases. The optimal therapy for this latter group remains to be determined.

Modulation of apoptosis by the widely distributed Bcl-2 homologue Bak

Members of the Bcl-2 family of proteins are characterized by their ability to modulate cell death. Bcl-2 and some of its homologues inhibit apoptosis, whereas other family members, such as Bax, will accelerate apoptosis under certain conditions. Here we describe the identification and characterization of a complementary DNA that encodes a previously unknown Bcl-2 homologue designated Bak. Like Bax, the bak gene product primarily enhances apoptotic cell death following an appropriate stimulus. Unlike Bax, however, Bak can inhibit cell death in an Epstein-Barr-virus-transformed cell line. The widespread tissue distribution of Bak messenger RNA, including those containing long-lived, terminally differentiated cell types, suggests that cell-death-inducing activity is broadly distributed, and that tissue-specific modulation of apoptosis is controlled primarily by regulation of molecules that inhibit apoptosis.

Structural and electronic factors in heterolytic cleavage: formation of the Co(I) intermediate in the corrinoid/iron-sulfur protein from Clostridium thermoaceticum

We have completed the first direct structural characterization of an enzyme-bound four-coordinate Co(I) intermediate, in this case for the corrinoid/iron-sulfur protein (C/Fe-SP) from Clostridium thermoaceticum. Extended X-ray absorption fine structure and X-ray edge spectroscopy of the active Co(I) state of the C/Fe-SP indicates a four-coordinate (distorted) square-planar structure where the best fit gives average Co-N(equatorial) distances of 1.87 +/- 0.01 A, corresponding to 4.2 +/- 0.3 ligands. The X-ray edge spectrum of Co(I) C/Fe-SP contains a moderate intensity 1s-4p + "shake-down" (SD) transition and no 1s-3d peak (where SD transitions are indicative of square-planar geometries). X-ray edge results for the methyl-Co(III) form, reported earlier [Wirt, M. D., Kumar, M., Ragsdale, S. W., & Chance, M. R. (1993) J. Am. Chem. Soc. 115, 2146-2150], are consistent with a base-off methylcobamide structure. The absence of a ligated 5-methoxybenzimidazole base in the methyl-Co(III) state is important since the base-off form is predicted to predispose the Co-C bond toward heterolytic cleavage to form the four-coordinate Co(I) species concurrent with methyl transfer. Additionally, we have examined first-derivative X-ray edge spectra of Co(I) C/Fe-SP, relative to edge spectra of a cobalt foil, as an indicator of effective nuclear charge on cobalt. The Co(I) C/Fe-SP edge position at 7720.5 +/- 0.3 eV is less than, but very close to, the value seen for the corresponding free Co(I) cobalamin.(ABSTRACT TRUNCATED AT 250 WORDS)