The structural parameters for antimicrobial activity, human epithelial cell cytotoxicity and killing mechanism of synthetic monomer and dimer analogues derived from hBD3 C-terminal region.

Understanding the molecular mechanisms of antimicrobial peptide-membrane interactions is crucial in predicting the design of useful synthetic antimicrobial peptide analogues. Defensins are small (3-5 kDa) cysteine-rich cationic proteins which constitute the front line of host innate immunity. In this study, a series of eight 10 AA C-terminal analogues of hBD3 [sequence: RGRKXXRRKK, X = W, F, Y, V, L, I, H, C(Acm); net charge = +7, coded as W2, F2, Y2, V2, L2, I2, H2, and C2] and covalent V2-dimer [(RGRKVVRR)(2)KK] (18 AA, net charge = +11) were synthesized using solid phase peptide synthesis (SPPS) in Fmoc chemistry. Wild-type hBD3 was used as a control in all analyses. W2, V2, and especially Y2 showed high activity selectively against Gram-negative bacteria Pseudomonas aeruginosa in the concentration range of 4.3-9.7 microM. The covalent dimeric form of V2-monomer, V2-dimer, showed increased antibacterial killing compared to the monomeric form, V2-monomer. Cytotoxicity assays on a human conjunctival epithelial cell line (IOBA-NHC cells) showed that no change in viable cell number 24 h after constant exposure to all the eight peptide analogues even at concentrations up to 200 microg/ml. Fluorescence correlation spectroscopy (FCS) was used to study the interaction of these peptides against POPC vesicles (neutral; mammalian cell membrane mimic) and POPG vesicles (negatively charged; bacterial cell membrane mimic). Using FCS, significant aggregation and some leakage of Rhodamine dye were observed with POPG with Y2, W2 and V2 at the concentration of 5-10 mmicroM and no significant aggregation or disruption of vesicles was observed for all peptide analogues tested against POPC. V2-dimer induced more leakage and aggregation than the monomeric form. Overall, V2-dimer is the most effective antimicrobial peptide, with aggregation of POPG vesicles observed at concentrations as low as 1 microM. The concentration of 5-10 microM for Y2 from FCS correlated with the concentration of 5 microM (6.25 microg/ml), at which Y2 showed a cooperative increase in the activity. This suggests a structural transition of Y2 in the 2.5-5 microM concentration range resulting in the correlated increased antimicrobial activity. These results and the FCS together with previous NMR and molecular dynamics (MD) suggested that the charge density-based binding affinity, stable covalent dimerization, the ability to dimerize or even oligomerize and adopt a well-defined structure are important physicochemical properties distinguishing more effective cationic antimicrobial peptides.

Timing of midazolam and propofol administration for co-induction of anaesthesia.

We aimed to determine the optimum timing of midazolam administration prior to propofol to achieve the maximal reduction in the dose of propofol required to induce anaesthesia. Female (ASA 1-2) patients, aged 18 to 45 years, weighing 40 to 75 kg and scheduled for gynaecological surgery were eligible for the study. Consenting patients were randomly assigned to six groups. Group 1 received saline and Groups 2 to 6 received midazolam 3 mg at 1, 2, 4, 6 or 10 minutes respectively prior to propofol (n = 20 to 22 per group) in a blinded manner. Propofol was administered i.v. over 10 seconds and flushed in with saline 5 ml. Two minutes later, the patient's response to pressure applied to the finger was determined as an index of loss of consciousness. The ED50 of propofol in each group was determined by the up-and-down method. Propofol ED50 was reduced to 34 to 67% (P < 0.001) in the midazolam treated groups. There was no significant (P = 0.14) difference in propofol ED50 among the five groups which received midazolam. Patients who received midazolam had less recollection of events surrounding induction (P < 0.001) and recalled the induction experience as being more pleasant (P = 0.03) than those who did not receive midazolam. These results indicate that midazolam may be given up to 10 minutes prior to propofol and still achieve a substantial dose reduction.

Distribution of hair on the dorsum of the phalanges of the hand in a Chinese population from Malaysia.

Hair distribution on the dorsum of phalanges of the hand was studied on 302 Chinese subjects (134 males and 168 females) randomly selected from the residents of Kota Bharu, Malaysia. Proximal phalangeal hair was seen on the dorsum of both hands in 99.3% of male subjects but in only 85.1% of female subjects. Chinese females showed a significantly lower (p < 0.05) incidence of proximal phalangeal hair on the hands than Chinese males. Comparison with other racial groups showed that Chinese females had significantly less (p < 0.05) hair on the proximal phalanges of the hands than Malay and African (Nigerian) females. The least common digital combination of proximal phalangeal hair in female subjects was the presence of proximal phalangeal hair only on the fourth digit (ring finger) and was noted in 0.6% of subjects. This has not been reported before. The frequency of middle phalangeal hair (MPH) distribution in Chinese falls between that in Malays and in Japanese which is probably explained by the fact that all these three racial groups originate from Asia. A study of digital combination of MPH in Chinese showed that the most common and the least common combinations in the Chinese differ considerably from those in other races. A total of 16 patterns of hair distribution was noted on the dorsum of the phalanges of the hands in Chinese subjects. Our study showed that though Chinese females had less digital hair on the hands than Chinese males, they showed a much larger variety of patterns of digital hair distribution than males.

The treatment of femoral shaft fractures by closed Küntscher nailing (without reaming).

Closed medullary nailing for fracture of the femoral shaft was carried out in 101 cases. The operation was performed with the patient in the supine position and without reaming the medullary canal, using the conventional instruments and rigid guide pins. The diameter of the medullary canal was gauged from standard radiographs taken at 1 m tobe-to-film distance. To secure alignment and reduction of the fracture, heavy traction before and during the operation was necessary. The traction applied on a fracture table against the restraining perineal bar caused trauma to the perineal structures in 7 cases. There was no case of deep infection. The fixation of the fracture was by no means rigid but was adequate for early walking and partial weight bearing. When nails with diameters of less than 9 mm were used, a number of complications occurred. These included angulation, rotational instability at the fracture site, fracture of the nail and non-union. Union occurred within 3 months in all except 2 cases. Nearly 60 per cent of the patients were in hospital for less than 2 weeks. Closed medullary nailing of the femur is preferable to the open method, which carries a much higher risk of infection.

Infantile fibrosarcoma: report of cases.

Infantile "fibrosarcoma" occurred in a newborn male infant and in a 2-month-old female infant. In both cases, the tumors grew rapidly and showed the histological features of malignancy. However, they were treated successfully with simple resections. Review of the literature shows that infantile fibrosarcoma has a relatively favorable prognosis. Simple local excision is the initial treatment of choice for lesions occurring in infants and children less than 5 years old.