The microbiology and the efficacy of antibiotic-based medical treatment of chronic rhinosinusitis in Singapore.

BACKGROUND: Medical therapy including appropriate antibiotic treatment is advocated for the management of chronic rhinosinusitis (CRS), with sinus surgery reserved for treatment failures. This study investigates the microbiology of CRS and their response to culture-directed antibiotic treatment. METHODS: Sinus aspirates of mucopus from 172 consecutive CRS patients, with (n=89) and without (n=83) previous antibiotic treatment, were obtained for bacterial culture at their first visit. Medical treatment which included initial empirical and subsequent culture-directed antibiotics was instituted. Endoscopic sinus surgery (FESS) was performed for patients with persistent CRS and/or complications of CRS. A follow-up of 12 months was scheduled for all patients. RESULTS: One hundred and twenty (69.8%) patients were treated successfully by with antibiotic-based medical therapy. Thirty-eight patients (22.1%) did not respond to medical treatment and eventually underwent FESS. The incidence of CRS with nasal polyps (CRSwNP) was higher in FESS group (n=13, 34.2%) than patients with medical treatment only (n=9, 6.7%). Staphylococcus aureus was the most common pathogen (n=43, 25%) and amongst patients with no prior antibiotic treatment, the incidence was higher in patients with CRSwNP (n=8, 53 %) than CRS without NP (CRSwoNP) (n=20, 27%). The rate of sensitivity of the cultured microbes to amoxicillin with clavulanate and cephalosporins was 78% and 70%, respectively. CONCLUSION: The microbiology of CRS in Singapore is described. Staphylococcus aureus appears to be the most common bacterial isolates in both CRS with and without nasal polyps. Medical treatment with CRS using culture-directed antibiotics is effective in the majority of patients, especially in patients without nasal polyps.

Ambulatory thyroid surgery: an audit of safety and outcomes.

INTRODUCTION: Elective hemithyroidectomy is a common operation with a low complication rate. The aim of this study was to conduct an audit on the safety and efficacy of ambulatory hemithyroidectomy in carefully-selected patients. METHODS: This is a cohort study of 114 patients who were scheduled to have either ambulatory (50 patients) or inpatient (64 patients) hemithyroidectomy over a two-year period. Selection for day case surgery was based on pre-established criteria and patient preference. Preoperative patient characteristics, indications for surgery, operative characteristics, histological diagnoses and surgical complications are compared. RESULTS: Of the 50 patients selected for day case surgery, 45 (90 percent) were discharged on the day of surgery. The complication rates of the two groups were similar. Two patients required admission for wound complications and the other three were admitted for non-medical reasons. CONCLUSION: The overall complication rate was low. There were no differences in the rate of complications between ambulatory and inpatient hemithyroidectomies. Ambulatory hemithyroidectomy can be performed safely for a select group of patients in the setting of appropriate facility and management protocol.

Sequence and analysis of chromosome 1 of the plant Arabidopsis thaliana.

The genome of the flowering plant Arabidopsis thaliana has five chromosomes. Here we report the sequence of the largest, chromosome 1, in two contigs of around 14.2 and 14.6 megabases. The contigs extend from the telomeres to the centromeric borders, regions rich in transposons, retrotransposons and repetitive elements such as the 180-base-pair repeat. The chromosome represents 25% of the genome and contains about 6,850 open reading frames, 236 transfer RNAs (tRNAs) and 12 small nuclear RNAs. There are two clusters of tRNA genes at different places on the chromosome. One consists of 27 tRNA(Pro) genes and the other contains 27 tandem repeats of tRNA(Tyr)-tRNA(Tyr)-tRNA(Ser) genes. Chromosome 1 contains about 300 gene families with clustered duplications. There are also many repeat elements, representing 8% of the sequence.

A gene encoding a novel multidomain beta-1,4-mannanase from Caldibacillus cellulovorans and action of the recombinant enzyme on kraft pulp.

Genomic walking PCR was used to obtained a 4,567-bp nucleotide sequence from Caldibacillus cellulovorans. Analysis of this sequence revealed that there were three open reading frames, designated ORF1, ORF2, and ORF3. Incomplete ORF1 encoded a putative C-terminal cellulose-binding domain (CBD) homologous to members of CBD family IIIb, while putative ORF3 encoded a protein of unknown function. The putative ManA protein encoded by complete manA ORF2 was an enzyme with a novel multidomain structure and was composed of four domains in the following order: a putative N-terminal domain (D1) of unknown function, an internal CBD (D2), a beta-mannanase catalytic domain (D3), and a C-terminal CBD (D4). All four domains were linked via proline-threonine-rich peptides. Both of the CBDs exhibited sequence similarity to family IIIb CBDs, while the mannanase catalytic domain exhibited homology to the family 5 glycosyl hydrolases. The purified recombinant enzyme ManAd3 expressed from the cloned catalytic domain (D3) exhibited optimum activity at 85 degrees C and pH 6.0 and was extremely thermostable at 70 degrees C. This enzyme exhibited high specificity with the substituted galactomannan locust bean gum, while more substituted galacto- and glucomannans were poorly hydrolyzed. Preliminary studies to determine the effect of the recombinant ManAd3 and a recombinant thermostable beta-xylanase on oxygen-delignified Pinus radiata kraft pulp revealed that there was an increase in the brightness of the bleached pulp.

Cloning of the xynB gene from Dictyoglomus thermophilum Rt46B.1 and action of the gene product on kraft pulp.

A two-step PCR protocol was used to identify and sequence a family 11 xylanase gene from Dictyoglomus thermophilum Rt46B.1. Family 11 xylanase consensus fragments (GXCFs) were amplified from Rt46B.1 genomic DNA by using different sets of consensus PCR primers that exhibited broad specificity for conserved motifs within fungal and/or bacterial family 11 xylanase genes. On the basis of the sequences of a representative sample of the GXCFs a single family 11 xylanase gene (xynB) was identified. The entire gene sequence was obtained in the second step by using genomic walking PCR to amplify Rt46B.1 genomic DNA fragments upstream and downstream of the xynB GXCF region. The putative XynB peptide (M(r), 39,800) encoded by the Rt46B.1 xynB open reading frame was a multidomain enzyme comprising an N-terminal catalytic domain (M(r), 22,000) and a possible C-terminal substrate-binding domain (M(r), 13,000) that were separated by a short serine-glycine-rich 23-amino-acid linker peptide. Seven xylanases which differed at their N and C termini were produced from different xynB expression plasmids. All seven xylanases exhibited optimum activity at pH 6.5. However, the temperature optima of the XynB xylanases varied from 70 to 85 degrees C. Pretreatment of Pinus radiata and eucalypt kraft-oxygen pulps with XynB resulted in moderate xylan solubilization and a substantial improvement in the bleachability of these pulps.

Cutaneous Rosai-Dorfman disease presenting as a suspicious breast mass.

Cutaneous Rosai-Dorfman disease in a male patient presented as a clinically malignant left breast mass. The intra-operative frozen section indicated a benign inflammatory lesion and a simple excision was performed. The disease was apparently limited to the skin and subcutis of the left breast with no lymph nodes or other organs involvement. While the lesion demonstrated the characteristic morphology of Rosai-Dorfman disease, the diagnosis of granulomatous mastitis, epithelioid sarcoma and other cutaneous xanthohistiocytic proliferations were considered. In the absence of lymphadenopathy, a high index of diagnostic awareness is required to recognize the uncommon, solitary cutaneous Rosai-Dorfman disease.

The effect of nifedipine and verapamil on nicotine-induced antinociception in rats.

We examined the modulatory effect of nifedipine (NIF, 0.04, 2, 5 and 15 mg/kg i.p.) and verapamil (VER, 2.5 and 10 mg/kg s.c.) on nicotine-induced antinociception in male rats, employing the tail-flick (TF) test. All rats were divided according to their responses to nicotine (1 mg/kg s.c.) alone, and classified as responders and nonresponders; both types were used. Both tested drugs were injected simultaneously with nicotine (NIC). In responders, NIC (1 mg/kg s.c.) alone produced a ceiling TF latency (15 sec) within 2.5 min lasting for 2.5 - 7.5 min. NIF, at the dose of 15 mg/kg i.p., prolonged this effect up to 40-50 min. Lower doses (5, 2 and 0.04 mg/kg) were not effective. VER in either dose did not prolong NIC-induced antinociception. In nonresponders, NIF also potentiated NIC-induced antinociception, and this effect appeared to be dose-related, lasting from 10 up to 40 min. VER was ineffective in either dose. These data support our hypothesis that calcium is involved, at least in part, in nicotine-induced antinociception. The potential risk for smoking patients treated with NIF is discussed.

Prenatal nicotine exposure increased duration of nicotine-induced analgesia in adult rats.

The effect of prenatal exposure to nicotine on nicotine-induced analgesia was studied in rats. The analgesic effect of a single dose of nicotine (1 mg/kg SC) was measured by the tail-flick technique, and two subsequent studies were carried out. In the first study, 7-month-old male rats, born to dams chronically treated with nicotine during pregnancy (NIC), exhibited prolonged nicotine-induced analgesia compared to matched controls. The second study was designed to explore whether rats prenatally exposed to nicotine (NIC rats) are born with an increased sensitivity to nicotine and whether there is any sex difference. The analgesic effect of nicotine was tested on control and NIC rats of both sexes once a month from 2 to 7 months of age. At an early age, male but not female NIC rats, exhibited shorter analgesic responses to nicotine than did the matched controls. With increasing age, however, the duration of nicotine analgesia began to be prolonged in NIC rats of both sexes. Significant differences between control and NIC rats were found at the age of 6 and 7 months, in both sexes. Thus, rats prenatally exposed to nicotine are not born with an increased sensitivity to the analgesic effect of a single dose of nicotine. This phenomenon develops later, during the course of life, independently of gender.

Modulation of nicotine-induced analgesia by calcium agonist and antagonist in adult rats.

The involvement of calcium in nicotine-induced analgesia in male rats was explored using the tail-flick test. A single dose of nicotine (1 mg/kg SC) produced a maximal effect on tail-flick latency (15 s) within 8-10 min, which lasted for 4 min. Pretreatment with the calcium chelator, EDTA (250 microM/kg SC four injections at 15 min intervals), before the single dose of nicotine accelerated the onset and prolonged the duration of the nicotine-induced analgesia. The maximal effect on tail-flick latency occurred within 2 min and lasted for 10-20 min. Conversely, pretreatment with calcium chloride (1.5 mM/kg IP) attenuated nicotine-induced analgesia. It is suggested that nicotine may exert its antinociceptive effects via modulation of calcium fluxes across the neural membrane.

Nicotine-induced analgesia in rats: the role of calcium and the diversity of responders and nonresponders.

Following a single dose of nicotine, (NIC, 1 mg/kg s.c.), 60% of tested rats revealed significant antinociception as measured by the tail-flick (TF) test, and were classified as responders, with those in which TF latencies did not change, nonresponders. The following experiments were carried out one week later. In nonresponders, pretreatment with ethylenediaminetetraacetic acid (EDTA, 250 microM/kg s.c. four times every 15 min) followed by 1 mg NIC, produced significant analgesia in 50% of rats, to the same magnitude as did nicotine alone (1 mg) in responders. The other 50% of rats which failed to respond to EDTA pretreatment, all revealed similar analgesia following the higher dose of NIC (1.5 mg/kg s.c.), with similar side effects, as generally observed in responders. In responders, pretreatment with CaCl2 (1.5 mM/kg s.c.) completely abolished NIC (1 mg/kg s.c.)--induced analgesia in all rats. Our data provide stronger evidence and a further verification that EDTA potentiates, whereas CaCl2 completely abolishes, nicotine-induced analgesia in rats; supporting our hypothesis of the involvement of calcium ions in this effect.