Pulse Compression of Harmonic Chirp Signals Using the Fractional Fourier Transform

In ultrasound harmonic imaging with chirp-coded excitation, a harmonic matched filter (HMF) is typically used on the received signal to perform pulse compression of the second harmonic component (SHC) to recover signal axial resolution. Designing the HMF for the compression of the SHC is a problematic issue because it requires optimal window selection. In the compressed second harmonic signal, the sidelobe level may increase and the mainlobe width (MLW) widen under a mismatched condition, resulting in loss of axial resolution. We propose the use of the fractional Fourier transform (FrFT) as an alternative tool to perform compression of the chirp-coded SHC generated as a result of the nonlinear propagation of an ultrasound signal. Two methods are used to experimentally assess the performance benefits of the FrFT technique over the HMF techniques. The first method uses chirp excitation with central frequency of 2.25 MHz and bandwidth of 1 MHz. The second method uses chirp excitation with pulse inversion to increase the bandwidth to 2 MHz. In this study, experiments were performed in a water tank with a single-element transducer mounted coaxially with a hydrophone in a pitch-catch configuration. Results are presented that indicate that the FrFT can perform pulse compression of the second harmonic chirp component, with a 14% reduction in the MLW of the compressed signal when compared with the HMF. Also, the FrFT provides at least 23% reduction in the MLW of the compressed signal when compared with the harmonic mismatched filter (HMMF). The FrFT maintains comparable peak and integrated sidelobe levels when compared with the HMF and HMMF techniques. (E-mail: elma@leeds.ac.uk)     

Effect of balneotherapy on temporospatial gait characteristics of patients with osteoarthritis of the knee

Effects of balneotherapy on gait properties of patients with osteoarthritis of the knee were investigated prospectively. A total of 30 patients with knee osteoarthritis received balneotherapy consisting of two daily thermomineral water baths for 2 weeks. Patients were evaluated using gait analysis and clinical scores, both within 2 weeks, before and after spa treatment. Patients were walking faster in their control analyses (0.81 ± 0.21 to 0.89 ± 0.19 m/s; P = 0.017), with a shorter mean stance time (63.0 ± 3.3 to 61.8 ± 2.5% stride; P = 0.007), an increased cadence (96 ± 13.1 to 100 ± 11.9 steps/min; P = 0.094) and stride length (996 ± 174 to 1,058 ± 142 mm; P = 0.017). Balneotherapy also resulted in a significant decrease in Lequesne knee osteoarthritis index (12.1 ± 3.7 to 10.0 ± 3.3 points; P = 0.003), VAS for pain (58 ± 25 to 33 ± 15; P = 0.0001), VAS for patients’ (56 ± 24 to 29 ± 19; P < 0.001) and investigator’s global assessment (55 ± 20 to 26 ± 15; P < 0.0001) and WOMAC score (2.1 ± 0.7 to 1.6 ± 0.8; P = 0.0004). Balneotherapy has positive effects on gait properties and clinical health quality parameters of patients with knee osteoarthritis in short-term evaluations.     

Antiproliferative potential of sarcophine and its semisynthetic sulfur-containing derivatives against human mammary carcinoma cell lines

The marine-derived cembranoid sarcophine (1) and its sulfur-containing semisynthetic derivatives (2–6) were evaluated for anticancer potential using cell cycle progression markers. No effect on MCF-7 cell viability or apoptosis was seen with these derivatives at concentrations of up to 100 μM after 72 h of incubation. At 100 μM, sarcophine and its derivatives 2–5 arrested the MCF-7 cells in G0/G1 phase, with concomitant decrease in the cell populations at S and G2+M phases. MDA-MB-231 cells were not responsive to any of the derivatives. Our preliminary results suggest that the sulfur-containing derivatives of sarcophine, especially 2 and 3, show potent and cell-specific antiproliferative activity.     

A study of aplastic anemia at the Department of Child Health, School of Medicine University of North Sumatera/Dr. Pirngadi Hospital, Medan.

A study of aplastic anemia in children in a period of June 1980 to June 1989 was done to evaluate the pattern of aplastic anemia in children. The cases consisted of 55 children, 30 males (54.55%) and 25 females (45.45%). Most of the patients (47.27%) were found in the age group of 10 to 15 years. The complaints were paleness (90.91%), fever (56.45%) and bleeding (52.72%). The hemoglobin concentration was 4.25 +/- 1.17 g/dl (mean +/- SD), and the thrombocytopenia was generally severe. Prednisone or combination of prednisone and oxymethalone was given in addition to blood transfusions, antibiotics and vitamins. The outcome was difficult to evaluate because of the irregularity of treatments. Of the 55 children, 9 (18.02%) contracted leukemia after 1-5 months.     

Prevalence and risk factors of work related asthma by industry among United States workers: data from the third national health and nutrition examination survey (1988-94)

Objectives: To estimate the prevalence of work related asthma and work related wheezing in United States workers. To identify high risk industries that could be targeted for future intervention. To determine the population attributable risk of work related asthma and work related wheezing.

Methods: The third national health and nutrition examination survey, 1988–1994 (NHANES III) was analyzed to determine the prevalence of work related asthma and wheezing and to identify initially defined industries at risk among United States workers aged 20 and older. Separate logistic models were developed with work related asthma and work related wheezing as outcomes. Work related asthma was defined as affirmative response to questions on self reported physician diagnosed asthma and work related symptoms of rhinitis, conjunctivitis, and asthma. Work related wheezing was defined as affirmative response to questions on self reported wheezing or whistling in the chest in the previous 12 months and work related symptoms of rhinitis, conjunctivitis, and asthma. All analyses were adjusted for age, sex, smoking, and atopy.

Results: The prevalence of work related asthma was 3.70% (95% confidence interval (95% CI) 2.88 to 4.52) and the prevalence of work related wheezing was 11.46% (95% CI 9.87 to 13.05). The main industries identified at risk of work related asthma and wheeze included the entertainment industry; agriculture, forestry, and fishing; construction; electrical machinery; repair services; and lodging places. The population attributable risk for work related asthma was 36.5% and work related wheezing was 28.5%.

Conclusions: The findings provide impetus for further research and actions by public health professionals which prioritise occupational asthma on the public health agenda. Future intervention strategies need to be developed for effective control and prevention of asthma in the workplace.

     

Incidence of cochlear involvement in hyperbilirubinemic deafness

Neonatal hyperbilirubinemia remains an important cause of childhood deafness, especially in developing countries. After neonatal hyperbilirubinemia, the auditory neural pathways, cochlea, or both may be affected. In this study, we aimed to determine the incidence of cochlear impairment and the appropriate means of hearing screening in hyperbilirubinemic neonates. A retrospective review of 1,032 pediatric patients with hearing loss revealed 67 cases (6.5%) of severe hyperbilirubinemia in the neonatal period. Thirty of these patients had neonatal hyperbilirubinemia as the single identifiable risk factor for hearing loss. In 26 of 30 cases (87%), otoacoustic emissions (OAEs) were absent, whereas in the remaining 4 cases (13%), robust emissions were detected despite an absent auditory brain stem response (ABR). Auditory screening of newborns with jaundice by OAEs possesses a significant risk of undiagnosed deafness. On the other hand, if the ABR is used as the single means of screening, auditory neuropathic conditions will probably be underlooked. Therefore, we recommend dual screening of hearing by ABR and OAEs in hyperbilirubinemic newborns.     

Effect of D-2 amino-5-phosphonopentanoate and nifedipine on postsynaptic calcium changes associated with long-term potentiation in hippocampal CA1 area

The induction of long-term potentiation (LTP) in CA1 hippocampal area requires a rise in intracellular postsynaptic calcium. Two major calcium mechanisms may mediate the transmembrane calcium influxes that contribute to this calcium accumulation: the N-methyl-D-aspartate (NMDA) receptor channels, which are voltage dependent and have large calcium permeability and voltage-dependent calcium channels (VDCCs). We have addressed the relative contribution of these routes of calcium entry before and during LTP expression, in synaptically evoked dendritic calcium transients from a population of CA1 pyramidal neurons. Combining the use of the fluorescent calcium indicator Fura-2 with field potential measurements, we observed that the calcium transients evoked by single stimuli, during the maintenance phase of LTP, were enhanced. These transients were not affected by D-2 amino-5-phosphonopentanoate (D-APV) (50 microM), an antagonist of NMDA receptors but were reduced by approximately one-quarter, in the presence of the L-type VDCCs blocker nifedipine (10 microM). During tetanic stimulation (100 Hz, 1 s) the components triggered by the activation of those two calcium mechanisms had comparable magnitudes representing the sum about half of the intracellular calcium accumulation. Thus, following both single and high frequency stimulation, a substantial fraction of calcium entry may occur through other types of VDCCs or be due to calcium release from intracellular stores.     

Serum immunoglobulin levels in neoplastic disorder of breast

Serum IgG, IgA and IgM were estimated in 42 cases of carcinoma and 12 cases of fibroadenoma of breast. The results were compared with 20 healthy female controls. Results showed increased levels of serum IgA in carcinoma breast cases. This increase was statistically significant (p = 0.001) when compared with healthy controls while IgG and IgM values were found to be insignificant. Values of IgG, IgA and IgM in cases of fibroadenoma breast when compared with the controls were found to be insignificant. Statistically significant increased value of IgA was also observed in medullary carcinoma and non-metastasizing tumours when viewed separately, suggestive of good prognostic index of serum IgA level estimation in the case of carcinoma breast.