Patent ductus arteriosus in neonates

Patency of the ductus arteriosus is one of the more common problems of the neonate. Although the ductus arteriosus usually closes within the first days of life, persistent patency can complicate the clinical status of a newborn. The ductus arteriosus also may play a role in the pathophysiology of persistent pulmonary hypertension of the newborn and in some forms of congenital heart disease. Diagnosis of patent ductus arteriosus can be suspected clinically but should be verified by echocardiography before treatment. Accurate diagnosis, early intervention and proper treatment are necessary to decrease the immediate risks and minimize the potential for long-term complications.     

Extent and effect of surface tilt on the data display of the EyeSys videokeratoscope

AIMS: This study examined the occurrence, magnitude, and the consequences of a possible tilt between the corneal surface and optical axis of the EyeSys videokeratoscope. METHODS: Initially, a theoretical model was developed to calculate the angle of tilt. The predictions of the model were verified empirically using a convex conicoid surface and were found to predict the tilt to within 0.5 degree of the actual tilt. The likely effects of the tilt on the corneal power were also examined. The angle of tilt was then measured on the human cornea and the effect of neutralising the tilt on the videokeratoscopic data display was observed. RESULTS: The angle of tilt was found to lie between 1 degree and 6 degrees in a temporal direction. CONCLUSION: When the corneal tilt on the human subjects was neutralised, then a reduction in the nasal/temporal asymmetry was observed.     

Acute angiographic and clinical results of long balloon percutaneous transluminal coronary angioplasty and adjuvant stenting for long narrowings

Historically, long coronary artery stenoses undergoing percutaneous transluminal coronary angioplasty (PTCA) are reported to have reduced procedural and clinical success in comparison with shorter lesions. The efficacy of long balloons (30 or 40 mm) in long lesions was evaluated. Eighty-two patients had 84 PTCA procedures with a primary long balloon. In all, 86 lesions were available for analysis. Data were collected prospectively on standard PTCA procedure forms. Coronary angiograms were reviewed and measured with digital calipers. Hospital charts were examined for complications. PTCA was performed in the left anterior descending artery in 44 cases (51%), the right coronary artery in 29 (34%) and the circumflex artery in 13 (15%). With the use of a modified classification system, 47 lesions (55%) were class C, 24 (28%) were class B2 and 15 (17%) were class B1. Mean lesion length was 22 +/- 11 mm (range 10 to 72), and 38 lesions (44%) were > or = 20 mm. Twelve patients received an intracoronary stent. The long balloon alone produced angiographic success (< 50% residual stenosis) in 77 lesions (90%). Angiographic success was achieved ultimately in all stenoses, using a stent in 7 patients and a short balloon in 2. There were 2 deaths (2%) and 1 Q-wave myocardial infarction (1%). One patient needed coronary artery bypass surgery. Clinical success without death, Q-wave infarction or bypass surgery was achieved in 83 of 86 procedures (97%). In conclusion, the use of long PTCA balloons with adjuvant stenting produced excellent results in these long stenoses. Lesion length was not a precursor of poor angiographic or clinical outcome.     

Glucose repression/derepression in budding yeast: SNF1 protein kinase is activated by phosphorylation under derepressing conditions, and this correlates with a high AMP:ATP ratio

BACKGROUND: Genetic studies of Saccharomyces cerevisiae have shown that Snf1p and Snf4p, which together form the SNF1 complex, are essential for gene derepression on removal of glucose from the medium. However the metabolic signal(s) involved, and the exact role of SNF1, have remained enigmatic. Recently, the AMP-activated protein kinase (AMPK) was shown to be the mammalian homologue of SNF1. AMPK is activated by the elevation of the cellular AMP:ATP ratio, which occurs during cellular stress in mammalian cells. The mechanism of activation involves phosphorylation of AMPK by an upstream protein kinase (AMPKK). We have investigated whether a similar mechanism might explain the role of SNF1 in yeast in the response to the stress of glucose starvation. RESULTS: The protein kinase activity of SNF1 was dramatically and rapidly activated by phosphorylation on removal of glucose from the medium. SNF1 was not activated directly by AMP, but could be inactivated by protein phosphatases and reactivated by mammalian AMPKK. We also demonstrated that an endogenous SNF1-reactivating factor, most likely an upstream protein kinase, is present in yeast extracts. Under a variety of different growth conditions, there was a correlation between cellular adenine nucleotide levels and the activation state of SNF1. CONCLUSIONS: Apart from the lack of direct allosteric activation of SNF1 by AMP, the regulation of the mammalian AMPK and yeast SNF1 protein kinase cascades is highly conserved. Adenine nucleotides are now good candidates for metabolic signals which indicate the lack of glucose in the medium, triggering activation of SNF1 and derepression of glucose-repressed genes.     

A kinetic model for the competitive reactions of ozone with amino acid residues in proteins in reverse micelles

Lysozyme and 10 other proteins are solubilized in reverse micelles formed by 0.1 M sodium di-2-ethyl-hexylsulfosuccinate and 2.0-2.5 M water (pH 7.4) in isooctane solvent. Exposure of the protein-containing reverse micellar solutions to ozone causes oxidative damage to the proteins, as assessed by the oxidation of tryptophan residues. The oxidation product of the protein-bound tryptophan has a molar absorption coefficient of 3275 +/- 81 M-1 cm-1 (mean +/- S.D., n = 6) at 320 nm. The product is suggested to be a Criegee ozonide or a tautomer of the Criegee ozonide and not N-formylkynurenine. Ozonation of lysozyme in reverse micelles results in the formation of hydrogen peroxide in yields of only approximately 0.07 mol/mol of tryptophan residues oxidized. The recovery of hydrogen peroxide added as an internal standard to the lysozyme-containing reverse micellar solutions ranges from 84 to 88%, whether or not the samples are subjected to ozonation. This suggests that hydrogen peroxide is neither destroyed during the process of ozonation nor consumed by the protein to a significant extent in an adventitious reaction. A kinetic model for the overall reaction of ozone with the proteins is developed, taking into account the concentrations and the reactivities of individual amino acid residues toward ozone. The model predicts the fractional reaction of ozone with tryptophan residues in the proteins, despite differences in amino acid composition, molecular weight, and tertiary structures. The lack of influence of protein structure is confirmed further by the observation that the native lysozyme (with and without external S-carboxymethylcysteine) and S-carboxymethylated lysozyme give identical values of the fractional reaction of ozone with tryptophan residues. The kinetic equations for the competitive reactions of ozone with amino acid residues in proteins, with some minor modification, are applicable to ozonations on complex mixtures of lipids, proteins, and antioxidants.     

Evaluation of prosthetic valve function and associated complications

Significant advances in imaging modalities have occurred to evaluate prosthetic valve function and associated complications. These developments involve predominantly the introduction of Doppler technology for the non-invasive determination of gradients and valve areas and TEE for an improved assessment of valve structure, function, and associated complications. The current role of cinefluoroscopy is mostly to complement TEE in the evaluation of motion of mechanical prosthetic valves in the aortic position. Cardiac catheterization is now rarely needed to assess valve function. Diagnosis of prosthetic valve obstruction can be performed in the majority of cases with transthoracic Doppler echocardiography. Differentiation of valve obstruction from normal valve function in small valves with high flow conditions, however, may be difficult. Because of this and the variability in normal valves among different prostheses, knowledge of the type and size of the implanted valve is essential. Patients and ultrasound laboratories are encouraged to seek and provide this information on a routine basis. Although transthoracic echocardiography is the main diagnostic modality for the serial evaluation of prosthetic valve function, it is important to recognize its limitations in assessing prosthetic mitral regurgitation and evaluating structural abnormalities of prosthetic valves. These are the situations in which TEE has the most impact. A summary of general indications of TEE in prosthetic valves is provided in Table 6. Finally, a baseline transthoracic Doppler study is essential in the overall follow-up and serial evaluation of valve function. For future comparisons, the best indices of valve functions are those obtained for patients as their own control, from a baseline Doppler echocardiographic study performed early after the operation.     

A randomized controlled trial of extraperitoneal bupivacaine analgesia in laparoscopic hernia repair

BACKGROUND: This study was designed to determine the frequency of surgical site infection development after discharge from the hospital after abdominal or vaginal hysterectomy and the frequency of use of antimicrobial prophylaxis in this patient group. METHODS: A prospective cohort study was performed on patients undergoing abdominal or vaginal hysterectomy between February 1 and December 31, 1995. Surgeons were contacted 1 month after the operations to determine which patients had acquired surgical site infections. Surgical site infection rates were calculated according to procedure, surgeon, and National Nosocomial Infection Surveillance system risk categories. A retrospective pharmacy record review was conducted to determine antimicrobial prophylaxis use according to procedure and surgeon. RESULTS: A total of 763 cases were surveyed; 55 (7.2%) met criteria for postoperative surgical site infection (7.7% abdominal and 4.5% vaginal hysterectomy). National Nosocomial Infection Surveillance system moderate-risk patients had significantly higher infection rates than did low-risk patients for both abdominal (p = 0.045) and vaginal (p = 0.05) procedures. Most patients (71.1%) were not given antimicrobial prophylaxis. There was a wide range of antimicrobial prophylaxis use by surgeon (3.6% to 94.4% of patients, p < 0.01). CONCLUSION: Despite long-standing and widespread recommendations for antimicrobial prophylaxis before hysterectomy, most of our patients were operated on without such prophylaxis. Surveillance programs permit detailed review of patient care practices that may reveal opportunities for improvement.     

Simple excision of the trapezium for osteoarthritis of the carpometacarpal joint of the thumb

We have reviewed the results in 34 patients (39 operations) following simple excision of the trapezium for osteoarthritis of the basal joint of the thumb. The average age at operation was 57 years and the average follow-up was 6 years. All the patients were graded clinically and radiologically and were asked their opinion of the procedure. There was dramatic relief of pain following this procedure. Stability of the thumb was not compromised. When compared to the unoperated side, thumb length, thumb abduction and first web span were similar. There was a reduction in pinch strength (operated 8.1 k.p.a., non-operated 9.6 k.p.a.) and grip strength (operated 15.5 k.p.a., non-operated 19.5 k.p.a.) and an increase in MIP extension (operated 5.4 degrees, non-operated 2.9 degrees) following this procedure but the differences were not statistically significant. 11 patients (32%) had scar hyperaesthesia on testing but this was a clinical problem in two patients only (5%). Simple excision of the trapezium is a satisfactory procedure for the majority of patients with this disorder, but has a long post-operative rehabilitation period.