Novel lytic bacteriophage AB7-IBB1 of Acinetobacter baumannii: isolation, characterization and its effect on biofilm

Acinetobacter baumannii infections are difficult to treat due to biofilm formation. The literature shows paucity of data on A. baumannii bacteriophages and their application in biofilm control. In this report, we have isolated a new lytic bacteriophage, AB7-IBB1, infecting A. baumannii. Transmission electron microscopy revealed its resemblance to members of the family Siphoviridae, with a tail size of 240 × 10 nm and an icosahedral head 50 nm in diameter. Plaques were 3-5 mm in diameter after 24 h, increasing to 7-9 mm in three days. The phage genome size was determined to be ~75 kb. AB7-IBB1 could lyse 23 of 39 (59 %) clinical isolates of A. baumannii. It exhibited rapid adsorption (>99 % adsorbed in 5 min), a latency period of 30 min and a burst size of 125 PFU/infected cell. The phage affected A. baumannii biofilm formation on an abiotic surface (polystyrene) and a biotic surface (human embryonic kidney 293 cell line). It also showed biofilm control ability on an abiotic surface (polystyrene). FESEM visualization studies confirmed the detrimental effect of phage AB7-IBB1 on host biofilm. In conclusion, this study reports a novel lytic bacteriophage, AB7-IBB1, belonging to family Siphoviridae, with promising anti-biofilm properties.     

Improving postoperative pain management in subpectoral tissue expander implant reconstruction of the breast using an elastomeric pump

IntroductionPostoperative pain after breast surgery is one of the major factors contributing to delay in mobilisation and prolonged hospital stay. A retrospective analysis was performed of patients undergoing skin sparing mastectomy and insertion of a subpectoral implant. The aim was to determine whether the use of an elastomeric local anaesthetic pump improved pain control and length of stay.MethodsTwenty-five consecutive patients undergoing the above procedure were sited with an elastomeric local anaesthetic infusion pump intraoperatively, in addition to standard regular and pro re nata analgesia. The control group comprised 25 patients undergoing the same procedure in the same year who received standard analgesia alone. Visual analogue scale scores were recorded for the duration of inpatient stay, as was any further analgesic requirement.ResultsThe median age was 51 years (range: 26–75 years) in the intervention group and 50 years (range: 28–70 years) in the control group. The mean visual analogue scale score was 0.28 (standard deviation [SD]: 0.61) at 24 hours for the intervention group and 1.84 (SD: 0.37) for the control group (p<0.0001). The mean length of stay was 1.8 days (SD: 0.71 days) for the intervention group and 2.28 days (SD: 0.94 days) for the control group (p=0.15). There were no complications involving catheter placement, leakage or toxicity relating to use of the local anaesthetic.ConclusionsThere was significantly reduced pain with the use of the local anaesthetic infusion pump. The elastomeric pump is a step towards enhanced patient recovery after breast surgery in the case of skin sparing mastectomy and subpectoral tissue expander reconstruction.     

Renal cell carcinoma in peritoneal dialysis patients

Renal cell carcinoma is a rare but serious complication in ESRD patients. In these patients the incidence of renal cell carcinoma (RCC) is 20-40 times higher than in the general population. We performed a retrospective study to measure the incidence rate, prevalence, characteristics and survival among our peritoneal dialysis (PD) patients diagnosed with renal cell carcinoma. The study was carried out among 607 patients who were on the PD program from January 1997 to June 2002. RCC was detected in eight patients (four males and four females) with mean age of 52.1 +/- 10.6 years. Among these eight patients four were new cases that were diagnosed before the patients were started on dialysis (three in native kidneys and one in a transplanted kidney). In the other four patients the RCC was diagnosed after they had been on dialysis for 33-204 months (mean 60.75 +/- 50.48). We found an incidence rate of 1.3 per 1000 patients per year and a prevalence of 1.3%. Six of the eight patients had renal cysts. Tumor size was less than 7 cm in seven patients and in the other patient it was 8.5 cm. Seven of eight patients were alive at the time of study with a survival time ranging from 3-138 months (mean 122.25 +/- 88.2) months. In one patient, the RCC metastasised to the scalp, and, in two other patients, the tumors subsequently involved the second kidney. A cardiovascular complication was the cause of one death. Two patients received a renal transplant 36 and 66 months after diagnosis. We conclude that despite the low rate of metastases and mortality in our study, regular ultrasonography should be added to the follow-up of PD patients. Renal transplantation can be considered in these ESRD patients with RCC; however, close follow-up for metastases is recommended.     

Syndromic versus nonsyndromic atlantoaxial dislocation: do clinico-radiological differences have a bearing on management?

Background

This prospective study attempts to study the clinico-radiological differences between patients with syndromic AAD (SAAD), non-syndromic AAD (NSAAD), and AAD with Klippel–Feil anomaly (AADKFA) that may impact management.

Methods

In 46 patients with AAD [SAAD (including Morquio, Down, Larson and Marshall syndrome and achondroplasia; n?=?6); NSAAD(n?=?20); and, AADKFS (n?=?20)], myelopathy was graded as mild (n?=?17, 37 %), moderate (15, 32.5 %) or severe (14, 30.5 %) based on Japanese Orthopaedic Association Score modified for Indian patients (mJOAS). Basilar invagination (BI), basal angle, odontoid hypoplasia, facet-joint angle, effective canal diameter, Ishihara curvature index, and angle of retroversion of odontoid and vertebral artery (VA) variations were also studied.

Statistics

Clinico-radiological differences were assessed by Fisher’s exact test, and mean craniometric values by Kruskal–Wallis test (p value ≤?0.05 significant)

Results

Incidence of irreducible AAD in SAAD (n?=?0), NSA AD (11.55 %) and AADKFS (n?=?18.90 %) showed significant difference (p?=?0.01). High incidence of kyphoscoliosis (83 %) and odontoid hypoplasia (83 %) in SAAD, and assimilated atlas and BI in NSAAD and AADKFA groups were found. In AADKFA, effective canal diameter was significantly reduced(p?=?0.017) with increased Ishihara index and increased angle of odontoid retroversion; 61 % patients had VA variations. Thirty-five patients underwent single-stage transoral decompression with posterior fusion (for irreducible AAD) or direct posterior stabilization (for reducible AAD). Postoperative mJOAS evaluation often revealed persistent residual myelopathy despite clinical improvement.

Conclusions

Myelopathy is induced by recurrent cord trauma due to reducible AAD in SAAD, and compromised cervicomedullary canal diameter in NSAAD and AADKFA. SAAD in children may be missed due to incomplete odontoid ossification or coexisting angular deformities. In AADKFA, decisions regarding vertebral levels to be included in posterior stabilization should take into consideration intact intervening motion segments and compensatory cervical hyperlordosis. Following VA injury, endovascular primary vessel occlusion/stenting across pseudoaneurysm preempts delayed rehemorrhage.     

Compstatin, a peptide inhibitor of C3, prolongs survival of ex vivo perfused pig xenografts

Fiane AE, Mollnes TE, Videm V, Hovig T, Høgåsen K, Mellbye OJ, Spruce L, Moore WT, Sahu A, Lambris JD. Compstatin, a peptide inhibitor of C3, prolongs survival of ex vivo perfused xenografts. Xenotransplantation 1999; 6: 000-000 ©Munksgaard, Copenhagen Compstatin, a newly described C3-binding peptide, inhibits complement activation by blocking C3 convertase-mediated cleavage of C3. As the complement activation is an essential part of the rejection reaction, we evaluated the ability of Compstatin to delay or prevent hyperacute rejection in an ex vivo xenograft model. Porcine kidneys were perfused with fresh human blood containing either Compstatin (n=6) or a control agent (n=6). Graft survival and activation of complement, leukocytes and platelets both in the fluid phase and in the tissue were examined. The survival of the Compstatin-perfused kidneys (median, 380 min) was significantly (P=0.0036) longer than that of the controls (median, 90 min). The classical complement pathway (C1rs-C1inhibitor and C4bc) was significantly and equally activated in both groups during the first 60 min. C3 activation products increased fivefold and terminal complement complex eightfold in the control group, but no increase occurred in the Compstatin group during this period. Immunohistochemistry showed less C3 and fibrin deposition and immuno-electron microscopy showed less terminal SC5b-9 complement complex deposition in the Compstatin group. A significant change in total white cells, neutrophils, myeloperoxidase, and expression of the surface activation markers CD11b (CR3) and CD35 (CR1) and CD62 L ( l -selectin) was observed in both groups. Leukocyte activation was lower in the Compstatin group but the difference was not statistically significant. There were no differences in platelet counts, thrombospondin, soluble P-selectin or β-thromboglobulin between the groups. We conclude that Compstatin prolongs graft survival and suggest that it may be a useful agent for attenuating hyperacute rejection by inhibiting C3 and thus terminal complement pathway activation.     

Comparative analysis of the large fragment of the 5′ untranslated region (LF-5′ UTR) of serotype A foot-and-mouth disease virus field isolates from India

India is endemic for foot-and-mouth disease (FMD) and in recent years a unique group within serotype A, carrying a codon deletion at an antigenically critical site in capsid protein VP3 has emerged (VP3⁵⁹-deletion group). This tempted us to analyze the noncoding region, which is an under represented area, though critically associated with virus biology and pathogenesis. Analysis of the large fragment of 5′ untranslated region (LF-5′ UTR) of type A FMD virus revealed discrepancy in the overall tree topology between LF-5′ UTR and 1D region possibly due to independent evolution of coding and noncoding regions. The VP3⁵⁹-deletion group maintained its phylogenetic distinctness even at the LF-5′ UTR. Eighteen lineage specific signatures detected here support independent evolutionary paths for the lineages. Extensive deletions of 45 and 89 nucleotides corresponding to the pseudoknot region were noticed. Conservation pattern in the ‘A₂₅₃AACA’ motif in the cre/bus stem-loop indicates the importance of first three ‘A’ residues in VPg uridylylation. Of the three polypyrimidine tract binding protein (PTB) binding sites mapped on the internal ribosome entry site (IRES), the pyrimidine tract (Py tract) in the loop of domain 2 was found to be maximally conserved and it might be the major PTB binding site. Strikingly, a deletion group lineage specific transversion was noticed in the Py tract at the 3′ end of IRES without significantly affecting its in vitro infectious titer. Hence, we presume that for efficient cap-independent viral translation, either a minimum number of pyrimidine residues rather than a complete Py tract or a Py tract tolerating transversions only at specific locations and a core motif ‘CUUU’ within the Py tract is essential.     

Tooth in a cyst — Is it always a dentigerous cyst?

We present the case report of an 18-year-old female patient who presented with unilateral nasal obstruction. Computed tomography scanning revealed an unerupted molar in the posterior wall of the right maxillary sinus with a cystic swelling in the sinus. The preoperative diagnosis was a dentigerous cyst. The patient underwent endoscopic removal of the cyst and tooth. The operative findings and histopathology showed that it was an odontogenic keratocyst. This paper stresses the importance of diagnosing this condition and that a tooth in a cyst is not always dentigerous.     

Changes in hypothalamic gene expression associated with the arrest of pulsatile gonadotropin-releasing hormone release during infancy in the agonadal male rhesus monkey (Macaca mulatta)

This study examined whether changes in the levels of the messenger RNAs (mRNAs) encoding the gamma-aminobutyric acid (GABA) synthesizing enzymes, glutamate decarboxylase (GAD)65 and GAD67 and transforming growth factor-alpha (TGFalpha) in the hypothalamus are correlated with the arrest of pulsatile GnRH release during infancy in the agonadal male monkey. This experiment also provided the opportunity to examine changes in hypothalamic GnRH gene expression during this critical phase of primate development. Male rhesus monkeys were castrated at 1 week of age: four were killed 4-7 weeks after orchidectomy while pulsatile GnRH release was robust as reflected by high circulating LH levels, and four were killed at 12-15 months of age after establishing that pulsatile GnRH release had been arrested. GAD65, GAD67, TGFalpha, and GnRH mRNA levels were estimated using RNase protection assays employing homologous probes and the results were expressed relative to cyclophilin mRNA levels. GnRH peptide was measured by RIA. GAD65 and GAD67 mRNA levels in the hypothalamus of juveniles were significantly greater than those in neonatal monkeys. On the other hand, hypothalamic TGFalpha and GnRH mRNA (and peptide) levels in agonadal neonate and juvenile monkeys were indistinguishable. These results indicate that the molecular concomitants associated with bringing the hypothalamic GnRH pulse generator into check in agonadal neonatal males are not a mirror image of those previously reported at the time this neuronal network is reactivated at puberty when TGFalpha and GnRH gene expression increase and GAD65 and GAD67 mRNA levels remain unchanged. Thus, the neurobiological mechanism that reactivates pulsatile GnRH release at puberty is likely to involve more than a simple reversal of that underlying inhibition of the same network in late infancy.