A Fast Transient Response Capacitor-Less LDO with Transient Enhancement Technology.

This paper proposes a fast transient load response capacitor-less low-dropout regulator (CL-LDO) for digital analog hybrid circuits in the 180 nm process, capable of converting input voltages from 1.2 V to 1.8 V into an output voltage of 1 V. The design incorporates a rail-to-rail input and push-pull output (RIPO) amplifier to enhance the gain while satisfying the requirement for low power consumption. A super source follower buffer (SSFB) with internal stability is introduced to ensure loop stability. The proposed structure ensures the steady-state performance of the LDO without an on-chip capacitor. The auxiliary circuit, or transient enhancement circuit, does not compromise the steady-state stability and effectively enhances the transient performance during sudden load current steps. The proposed LDO consumes a quiescent current of 47 µA and achieves 25 µV/mA load regulation with a load current ranging from 0 to 20 mA. The simulation results demonstrate that a settling time of 0.2 µs is achieved for load steps ranging from 0 mA to 20 mA, while a settling time of 0.5 µs is attained for load steps ranging from 20 mA to 0 mA, with an edge time of 0.1 µs.

A Fast Transient Adaptive On-Time Controlled BUCK Converter with Dual Modulation.

This paper proposed a fully integrated adaptive on-time (AOT) controlled buck converter with fast load transient. An adaptive on-time generator is presented to stabilize the output frequency. To enhance the light load efficiency, the converter could transfer from the pulse width modulation (PWM) to pulse skip modulation (PSM) as the load current decreases. The buck converter can switch between these two modulation modes adaptively with the assistance of a zero current detection circuit. Implemented in the TSMC 0.18 µm BCD (BiCMOS/DMOS) process, the proposed buck converter works with an input voltage ranging from 5.5 to 15 V, an output voltage ranging from 0.5 to 5 V, and an output load ranging up to 5 A. The experimental results show that based on the dual modulation adaptive on-time controlled mode, the transient recovery time from light to heavy load and from heavy load to light load is 13 µs and 15 µs, respectively. An overshot voltage of 57 mV and an undershot voltage of 53 mV are also achieved.

Detection of high-risk human papillomaviruses in fresh breast cancer samples using the hybrid capture 2 assay.

The etiology of breast cancer remains unknown and the role of human papillomavirus (HPV) in breast carcinogenesis is controversial. This study investigated the prevalence of high-risk HPV infections in Chinese women with breast cancer and the possible relationship between high-risk HPV infection and the clinicopathological characteristics of breast cancer. Tumor cells from 224 fresh breast cancer samples and 37 fresh breast fibroadenomas were collected for hybrid capture 2 (HC2) assay. HC2 was the only technique approved by the United States Food and Drug Administration for screening for high-risk HPV infection in 2008. The prevalence of high-risk HPV infection in breast cancer samples was 21.4%, which was slightly higher than the 16.2% observed in breast fibroadenomas. Age and menopausal status were not risk factors for high-risk HPV infection among breast cancer patients. The clinical and pathological characteristics of breast cancer showed no significant correlation with high-risk HPV infection. Although the prevalence of 13 subtypes of high-risk HPV infections was similar in breast cancer and nonmalignant breast samples, the presence of high-risk HPVs in both malignant and benign breast samples implies that a possible causal role in breast cancer carcinogenesis could not be ruled out. Clarifying the possible link between high-risk HPVs and breast cancer might benefit women vaccinated against HPV and could decrease the incidence of HPV-related breast cancer.

Angiotensin-converting enzyme insertion/deletion (ACE I/D) and angiotensin II type 1 receptor (AT1R) gene polymorphism and its association with preeclampsia in Chinese women.

OBJECTIVE: To investigate whether polymorphisms of angiotensin converting enzyme gene (ACE) and angiotensin II receptor type 1 gene (AT1R) are associated with etiology of preeclampsia and renal impact in women with preeclampsia. METHODS: DNA was extracted from peripheral blood of 133 patients with preeclampsia and 105 healthy pregnant women. The I/D polymorphism of the ACE gene was assessed by polymerase chain reaction, and the A1166C polymorphism of the AT(1)R gene was additionally assessed by DdeI digestion. The level of proteinuria, fasting serum urea, creatinine and uric acid were investigated according to different genotypes of ACE and AT1R genes. RESULTS: The frequency of genotypes of the ACE gene and the AT1R gene was similar in preeclampsia and normal pregnancy. DD and ID genotype predominated in patients with severe proteinuria, as well as increased serum urea and uric acid. Serum creatinine was also increased, but no significant difference was found among three genotypes. The level of proteinuria, serum uric acid, urea, and creatinine did not vary between different AT1R genotypes. Compared with patients without renal dysfunction, the frequency of DD and ID genotypes of ACE gene was much higher in those with renal dysfunction, but AC and CC genotypes of AT1R gene were not. CONCLUSION: We found no association of the two gene polymorphisms with preeclampsia. However, ACE gene I/D polymorphisms were associated with the severe proteinuria and renal dysfunction seen in preeclampsia. Preeclampsia patients carrying the D allele may be susceptible to renal dysfunction.

[Oxidative stress in patients with chronic hepatitis B before and after interferon alpha-2b treatment].

OBJECTIVE: To investigate the impacts of interferon alpha-2b (IFN alpha-2b) on the oxidative stress states in the treatment of chronic hepatitis B (CHB) with different genotypes. METHODS: Thirty-five patients with chronic hepatitis B and 18 healthy volunteers as a control were enrolled in this present study. In control and patients group, the serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST), serum malondialdehyde (MDA) levels, serum total antioxidative stress capacity (TAC) were measured spectrophotometrically. After the therapy with interferon alpha-2b at the dose of 300 million units via intramuscular injection thrice a week for 12 weeks, these parameters were measured again in the patient group. The genotypes of hepatitis B virus were detected by polymerase chain reaction and hybridization. The effective group was defined as the patients with complete response and partial response. RESULTS: The elevated concentrations of MDA and impaired levels of TAC in the patients with CHB were observed as compared to the healthy controls (P < 0.05 for both). There were no significant differences in serum levels of MDA and TAC in CHB patients with various genotypes (P > 0.05). The serum levels of MDA after the treatment with IFN alpha-2b were significantly lower than the pretreatment levels (P < 0.05), which even returned to the normal concentration (P > 0.05) in the effective group. There were significant increases in the TAC after the IFN alpha-2b therapy in the effective group. However, the significant differences in the TAC levels before and after the INFalpha-2b treatment were not observed in the non-responsive group. CONCLUSION: The oxidative stress could be improved with IFN alpha-2b treatment of chronic hepatitis B patients. The results suggest that antioxidant treatment for chronic hepatitis B patients may help improve the effect of anti-virus therapy.

Establishment and application of a TaqMan real-time quantitative reverse transcription-polymerase chain reaction assay for rubella virus RNA.

The aim of this study was to establish and apply a real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR) for rubella virus (RV) RNA. First, the primer and TaqMan probe concentrations, as well as reaction temperatures were optimized to establish an efficient real-time quantitative RT-PCR assay for RV RNA. Next, an RV-specific PCR amplicon was made as an external standard to estimate the linearity, amplification efficiency, analytical sensitivity and reproducibility of the real time quantitative assay. Finally, the assay was applied to quantify RV RNA in clinical samples for rubella diagnosis. The RV-specific PCR amplicon was prepared for evaluation of the assay at 503 bp, and its original concentration was 2.75x109 copies/mul. The real time quantitative assay was shown to have good linearity (R2=0.9920), high amplification efficiency (E=1.91), high sensitivity (275 copies/ml), and high reproducibility (variation coefficient range, from 1.25% to 3.58%). Compared with the gold standard, the specificity and sensitivity of the assay in clinical samples was 96.4% and 86.4%, respectively. Therefore, the established quantitative RT-PCR method is a simple, rapid, less-labored, quantitative, highly specific and sensitive assay for RV RNA.

[Study on prenatal diagnosis using fluorescence quantitative polymerase chain reaction for congenital toxoplasmosis].

OBJECTIVE: To investigate prenatal diagnosis and treatment of toxoplasmosis in fetuses with fluorescence quantitative polymerase chain reaction (FQ-PCR) technique. METHODS: Of the 70 pregnant women with toxoplasma (TOX) DNA positive, TOX DNA in amniotic fluid and/or fetal umbilical cord blood was detected with FQ-PCR technique to diagnose fetal infection. 48 ones were given routine treatment with spiramycin for 2 therapy periods. Ultrasound examination were undertaken in all of pregnant women to monitor fetal growth. RESULTS: Of the 70 cases with TOX DNA positive, TOX DNA was detected in 21 fetuses. TOX DNA positive rates were similar in amniotic fluid and umbilical cord blood. The higher the TOX DNA, the higher fetal infectious rate. Fetal infectious rate was lower in treatment group (21%) than that in control group (50%), there was a statistically difference between two groups. CONCLUSIONS: Maternal TOX infection may cause fetal damage. Detection of TOX-DNA in amniotic fluid with FQ-PCR technique can diagnose fetal toxoplasmosis exactly. Treatment in pregnant period may decrease intrauterine infection rate.