MMM and MMMSynth: Clustering of heterogeneous tabular data, and synthetic data generation

We provide new algorithms for two tasks relating to heterogeneous tabular datasets: clustering, and synthetic data generation. Tabular datasets typically consist of heterogeneous data types (numerical, ordinal, categorical) in columns, but may also have hidden cluster structure in their rows: for example, they may be drawn from heterogeneous (geographical, socioeconomic, methodological) sources, such that the outcome variable they describe (such as the presence of a disease) may depend not only on the other variables but on the cluster context. Moreover, sharing of biomedical data is often hindered by patient confidentiality laws, and there is current interest in algorithms to generate synthetic tabular data from real data, for example via deep learning. We demonstrate a novel EM-based clustering algorithm, MMM ("Madras Mixture Model"), that outperforms standard algorithms in determining clusters in synthetic heterogeneous data, and recovers structure in real data. Based on this, we demonstrate a synthetic tabular data generation algorithm, MMMsynth, that pre-clusters the input data, and generates cluster-wise synthetic data assuming cluster-specific data distributions for the input columns. We benchmark this algorithm by testing the performance of standard ML algorithms when they are trained on synthetic data and tested on real published datasets. Our synthetic data generation algorithm outperforms other literature tabular-data generators, and approaches the performance of training purely with real data.

Altered kinetics of circulating progenitor cells in cardiopulmonary bypass (CPB) associated vasoplegic patients: A pilot study

Vasoplegia observed post cardiopulmonary bypass (CPB) is associated with substantial morbidity, multiple organ failure and mortality. Circulating counts of hematopoietic stem cells (HSCs) and endothelial progenitor cells (EPC) are potential markers of neo-vascularization and vascular repair. However, the significance of changes in the circulating levels of these progenitors in perioperative CPB, and their association with post-CPB vasoplegia, are currently unexplored. We enumerated HSC and EPC counts, via flow cytometry, at different time-points during CPB in 19 individuals who underwent elective cardiac surgery. These 19 individuals were categorized into two groups based on severity of post-operative vasoplegia, a clinically insignificant vasoplegic Group 1 (G1) and a clinically significant vasoplegic Group 2 (G2). Differential changes in progenitor cell counts during different stages of surgery were compared across these two groups. Machine-learning classifiers (logistic regression and gradient boosting) were employed to determine if differential changes in progenitor counts could aid the classification of individuals into these groups. Enumerating progenitor cells revealed an early and significant increase in the circulating counts of CD34+ and CD34+CD133+ hematopoietic stem cells (HSC) in G1 individuals, while these counts were attenuated in G2 individuals. Additionally, EPCs (CD34+VEGFR2+) were lower in G2 individuals compared to G1. Gradient boosting outperformed logistic regression in assessing the vasoplegia grouping based on the fold change in circulating CD 34+ levels. Our findings indicate that a lack of early response of CD34+ cells and CD34+CD133+ HSCs might serve as an early marker for development of clinically significant vasoplegia after CPB.

A brief review of recent discoveries in human anatomy

In the last few years, a cluster of anatomical discoveries has been reported which overturned the long existing dogmas about the structure and function of human body. First to come was the discovery that established the existence of a lymphatic system pertaining to the central nervous system (CNS). CNS was believed to be anatomically immune privileged owing to the absence of any lymphatics and presence of the blood-brain barrier around it, but latest research has established beyond any reasonable doubt that true lymphatic channels carry immune cells in meninges thus challenging the existing theory. Studies also supported the presence of a 'Glymphatic system' (created by the perivascular spaces lined with the leptomeninges and a sheath of glial cells) in the CNS draining interstitial metabolic waste from CNS. The second discovery unraveled the previously unknown parts of the human mesentery in adult and established that it is a continuous entity all along the intra-abdominal gut tube against the previous notion that it is fragmented in the adult humans. A very recently reported third discovery demonstrated a previously unknown tissue component-'interstitium'-a networked collagen bound fluid-filled space existent in a number of human organs. All these structures bear considerable applied importance towards the pathogenesis, prognostic and diagnostic investigations and management of human diseases. This article attempts to present a brief review of all three remarkable discoveries and emphasizes their applied importance within the realm of medical sciences.

An Experimental and Numerical Study on Nodular Gel Phantom during Cryotherapy

BACKGROUND

Cryogen spray cooling is an effective method to treat nodular basal cell carcinoma.

OBJECTIVE

To study the effect of spraying distance (z = 27 mm, 18 mm and 9 mm) on a nodular gel phantom and to validate the numerical model.

MATERIALS AND METHODS

Liquid nitrogen is sprayed on agarose gel phantom using 0.8 mm nozzle diameter. A two-dimensional Pennes equation with phase change is solved on the axisymmetric non-orthogonal grid.

RESULTS

The lethal front is obtained at 4 mm from the gel surface, irrespective of spraying distance and the same is validated with numerical results. The maximum necrotic volume and lethal front achieved by -50C and -25C isotherms seem to have a lower dependence on the spraying distance as opposed to those corresponding to the 0C isotherm. In contrast, the initiation of these parameters is highly dependent on the nozzle to gel height.

CONCLUSION

The numerical study presents good agreement with experimental data. The decrease in spraying distance leads to higher rate of maximum ablation volume during freezing, but final ablation volume remained approximately similar.

Lumbar sympathetic chain: anatomical variation and clinical perspectives

The sympathetic and parasympathetic nervous systems constitute the autonomic nervous system which controls the entropy of the body and maintain the equilibrium. The sympathetic chain forms a definitive anatomic entity which is quite variable with respect to its position and the number of ganglia. The sympathetic nervous system causes vasoconstriction and thus forms the basis of Lumbar sympathetic surgeries being performed in patients with peripheral vascular diseases. The anatomic variations in this region hence gains immense importance for the operating surgeons and consulting radiologists. In the present study, the rami communicantes of either side of lumbar sympathetic chain crossed the common iliac arteries from lateral to medial side and united in front of first piece of sacrum. These rami communicantes encircled the right gonadal artery and could be a threat to the gonadal vascularity causing infertility. This was an unusual feature of the lumbar sympathetic chain and its rami communicantes that were noted in this particular case.

Early Recognition of Fibrodysplasia Ossificans Progressiva-Important For the Clinician

Fibrodysplasia ossificans progressiva is a rare disorder of heterotopic ossification. Procedures like biopsy and surgery are known to be aggravating factors in promoting heterotopic ossification Clues to clinical diagnosis may therefore be a great advantage to treating orthopedician. Valgus deformity of great toe is an important diagnostic clue for treating physicians and thus aids in preventing the clinicians from subjecting the patients to unnecessary invasive and traumatic procedures. Hence clinical clues to early diagnosis are important in establishing the correct diagnosis and directing future management.

Contraceptive practices of women living in rural areas of Bihar

A prospective survey of 972 married (sexually active) women living in rural areas of Lalganj block of Vaishali district in Bihar state of India was carried out. The study was aimed at obtaining first hand information from the rural women regarding their contraceptive practices and to use the information thus gained to identify those spheres of concern where greater attention needs to be paid to make the family planning system more efficient. The population investigated consisted of women attending the combined obstetric and gynaecology clinic located at Lalganj. Tubal sterilisation was the commonest method of contraception among women surveyed ( 20.6 per cent of women). The incidence of sterilisation increased significantly as the age increased-11.6 per cent of women aged 21 to 30 had tubal sterilisation, whereas the incidence was 51 per cent in women aged 31 to 40 years. Reversible forms of contraception (IUD, oral pills and condoms) were used by only 6.8 per cent of women included in the study. Married girls aged 15 to 20 were not using any contraceptive. It was also noted that none of the women surveyed had used any contraceptive prior to her first pregnancy. Fortyper cent of women in the age group 21 to 30 years and a similar percentage (41.1 per cent) in the age group 31 to 40 years had two or more live children but did not use any contraceptive. The results reveal that tubal sterilisation is the most popular method of contraception among women living in rural areas of the state. Birth spacing, or delaying the birth of the first child by the use of reversible forms of contraception, is not the common practice among these women.