Proline, a multifaceted signalling molecule in plant responses to abiotic stress: understanding the physiological mechanisms

Abiotic stresses have a detrimental impact on plant growth and productivity and are a major threat to sustainable crop production in rapidly changing environments. Proline, an important amino acid, plays an important role in maintaining the metabolism and growth of plants under abiotic stress conditions. Many insights indicate a positive relationship between proline accumulation and tolerance of plants to various abiotic stresses. Because of its metal chelator properties, it acts as a molecular chaperone, an antioxidative defence molecule that scavenges reactive oxygen species (ROS), as well as having signalling behaviour to activate specific gene functions that are crucial for plant recovery from stresses. It also acts as an osmoprotectant, a potential source to acquire nitrogen as well as carbon, and plays a significant role in the flowering and development of plants. Overproduction of proline in plant cells contributes to maintaining cellular homeostasis, water uptake, osmotic adjustment and redox balance to restore the cell structures and mitigate oxidative damage. Many reports reveal that transgenic plants, particularly those overexpressing genes tailored for proline accumulation, exhibit better adaptation to abiotic stresses. Therefore, this review aims to provide a comprehensive update on proline biosynthesis and accumulation in plants and its putative regulatory roles in mediating plant defence against abiotic stresses. Additionally, the current and future directions in research concerning manipulation of proline to induce gene functions that appear promising in genetics and genomics approaches to improve plant adaptive responses under changing climate conditions are also highlighted.

Comparison of foetomaternal circulation in normal pregnancies and pregnancy induced hypertension using color Doppler studies

The aim of present study was to assess fetomaternal blood flows in normal and abnormal pregnancies using color Doppler indices. Subjects were divided into two groups as: Group A of 25 subjects of normal pregnancy as controls and group B of 25 subjects of pregnancy induced hypertension. All the subjects were lying in the age-group of 25-35 years and having 28 to 34 weeks of gestation; the patients were evaluated by detailed history and were subjected to complete general examination. Blood pressure was taken on two occasions at least 6 hours apart. Systemic examination and obstetrical examination was done in all subjects. All cases were subjected to pathological tests- Haemogram, Test for proteins in urine. Ultrasound assessment of fetal growth was done by measuring BPD (Biparietal diameter), HC (Head circumference), FL (Femur length) and AC (Abdominal circumference): Average gestational age and effective fetal weight was then calculated by ultrasound machine. Color Doppler was used to assess the various Doppler indices indices: Pulsatility index (PI), Resistive index (RI) and Systolic diastolic ratio (S/D ratio) in bilateral uterine, umbilical and middle cerebral arteries and compared to the standard normograms. Percentage of subjects having abnormal Doppler indices were calculated. Assessment of percentage of SGA (small for gestational age) fetuses was done in all the three groups. Decline in mean values of all Doppler indices was found with advancing gestational age in normal pregnancy suggesting decreased vascular resistance and increased blood flow in fetomaternal circulation. In pregnancy induced hypertensives, the mean values of Doppler indices showed a decline as in normal pregnancy but showed an increase (more than 2 S.D. of the mean) for that gestational age in comparison to the control group suggesting increased impedance to blood flow in uteroplacental and fetomaternal circulation. Umbilical artery Doppler indices were found to be the most sensitive indicator of uteroplacental and fetoplacental insufficiency in pregnancy induced hypertensives (P = 0.001). Thus we concluded that color Doppler can detect changes in fetomaternal circulation which correlate strongly with the fetal growth and therefore associated with pregnancy outcome.

Incidence of adenomatous hyperplasia in postmortem cirrhotic livers and study of cellular proliferative indices by light microscopy

BACKGROUND

Adenomatous hyperplasia (AH) or dysplastic nodule in the liver is considered a preneoplastic lesion. A wide range in its incidence has been reported.

AIMS

To study the incidence of AH nodules in autopsy cirrhotic livers and to carry out a comparative study of the cellular proliferative indices.

MATERIALS

Retrospective study of 150 cases with cirrhosis of variable etiology at autopsy, over a 15-year period.

METHODS

We identified AH on gross examination and studied the morphology. We compared cellular proliferative indices in AH nodules with other liver nodules by using PCNA monoclonal antibody and AgNOR.

RESULTS

Alcohol was the commonest etiology (30%), followed by HBsAg positivity (38%). Most patients belonged to the 30-60 years age group, with male predominance. Sixty of the 150 livers showed AH nodules; there were one to four nodules, measuring 6 mm to 50 mm, per liver. 115/122 AH nodules were studied. Ordinary AH (OAH) was seen in 104 and atypical AH (AAH) in 11, with malignant focus (MF) in four. Associated hepatocellular carcinoma (HCC) was seen in 7 cases. A gradual increase in the proliferative indices from surrounding regenerating nodules (SRN) and OAH to AAH to AAH with MF to HCC was observed. In addition, AAH also showed relatively less reticulin fibers.

CONCLUSION

The incidence of AH was 40%. In addition to the cellular proliferative indices, relatively less reticulin fibers could be a distinguishing feature for AAH from SRN, OAH and HCC.

The history of geriatric medicine in Scotland

The concept that care of elderly people required special facilities and training started early this century but was only implemented with the advent of the NHS in 1948. In Scotland the speciality gradually evolved and grew in stature and prominence. The early pioneers in Scotland are described.

A novel approach to the assessment of drug compliance in the elderly

A reliable drug history is not always available, and the constant accurate updating of patients' current medication at a Day Hospital may be difficult. This pilot study examined the use of a qualitative thin-layer chromatographic technique (Toxi-Lab system) applied to urine specimens in assessing drug compliance in the elderly. The system proved capable of detecting 36% of prescribed drugs in a group of elderly patients, and offers a novel and inexpensive approach to monitoring compliance with certain medications.

A simple regression model for estimating gestational age in later pregnancy by ultrasonography

Three hundred and six antenatal women with confirmed LMP underwent a single real time ultrasonographic examination between 32-40 weeks of gestation. Four parameters viz. BPD, HL, FL and AP having a positive correlation with gestational age were studied. A multiple regression model for predicting gestational age by a single ultrasonographic examination was developed by forward selection method after eliminating multicollinearity; as a high degree of intercorrelation was found between FL and HL, HL was eliminated from the data. The BPD does not have a significant role in predicting gestational age in later pregnancy. The proposed regression equation with FL and AP predicts gestational age 75% of time within +/- 10 days of 95% confidence limit.