Ability of animals to detect cancer odors

The olfactory capacity of animals has long been used by humans to help with various activities, e.g., hunting, detecting mines, locating people, and diagnosing diseases. Cancer is among the leading diseases causing death worldwide. Several recent studies have underscored the benefit of using scent to detect cancer, and this paper will review the studies using animals to detect tumor scents. A large variety of animals have been used for this purpose—dogs, rodents, insects, and nematodes—and have shown their capacity to detect cancer, with a success rate close to 90%. Here we discuss these studies, their methodologies, and the animal models used. Finally, we discuss the medical perspectives for cancer diagnosis using odors.     

N. I. Vavilov-the man and his work

A brief sketch is presented of Vavilov's career, his main contributions to science and personal qualities. The imporatnce of his work in genetics, agro-ecology, plant breeding, the experimental taxonomy of crop plants and genetic resources conservation is also emphasized.     

Spectral analysis of breathing pattern in man

The periodic oscillations of breathing pattern parameters were studied in 34 healthy subjects. In a three minutes' resting spirometric recording we determined the duration of inspiration, expiration and tidal volume in successive breaths and computed autocorrelation functions and power spectral density. Ten of the subjects were re-examined 2 years later. Pulmonary functions were examined in all of them. Rhythmic changes lasting several respiratory cycles were found in the breathing pattern. Rhythmic changes in the duration of inspiration, expiration and tidal volume differed from one another in the same individual. The spectrograms of the individual breathing pattern parameters in the same individual changed during a 2-year period. Despite individual differences, the power spectral density correlations in the same subject and between different subjects two years later, and the mean curves for power spectral densities, show that in all the subjects the power fell at values of 0 to 0.05 Hz and was then maintained at a roughly constant level. Differences in the spectrograms of the various parameters in the same subject can hardly be attributed to a feedback between peripheral receptors and respiratory centres. Rhythmic changes are probably of central origin.     

Indomethacin increases abortifacient effect of PGE2 in man.

Results of this study indicate that pretreatment with indomethacin significantly increases the abortifacient effect of an intravenous infusion of PGE2 in patients admitted for abortion as a result of fetal death in utero. Indomethacin pretreatment shortened the duration of PGE2-induced abortion in primigravid and multigravid groups of patients by about 4 and 2 hours respectively. When primigravid and multigravid groups were combined, the dose of PGE2 needed for complete delivery decreases in the indomethacin-treated group by 39.9%.     

Central and peripheral mechanisms of difficult breathing in man

The review is dedicated of phenomenology of the difficult breathing and analysis of the peripheral and central mechanisms of it. Analysis based on model investigations with resistive loads in awake or sleeping healthy humans, including results of experiments in the anesthetized animals. The recent data having principle importance in estimation of the central mechanisms of the control breathing are included too in the review. It concerned to the contemporary visualization of central neuronal activity on the awake person during dyspnoea. It became possible due to application of the unique precision equipment--functional magnetic--resonance and positron--emission tomography.     

Relationships between eupnoeic pattern of breathing and ventilatory control in man II. Early response to transient hypercapnia.

The individual importance of peripheral chemosensitive afferents was studied using a transient hypercapnia (inhalation of a 5% or a 10% CO2 in air gas mixture respectively during 4 or 2 breaths) in human conscious subjects chosen for their different eupnoeic ventilatory patterns. Calculation of the speed of change in end-tidal CO2 pressure in tracheal gas (sPETCO2) and of the rate of change in tidal volume (sVI) gave assessment for quantifying the sensitivity of arterial chemoreceptors to hypercapnia (sCO2=SVI/SPETCO2). Our results showed that, independently of any outside influence of the eupnoeic ventilatory pattern on the components of the chemical stimulus, sVI and sCO2 were found to be much smaller in subjects whose pattern of breathing was slow (i.e. having a large tidal volume). The possible causes of the weak importance of peripheral chemosensitive afferents in such subjects were discussed.     

A sequence sub-sampling algorithm increases the power to detect distant homologues

Searching databases for distant homologues using alignments instead of individual sequences increases the power of detection. However, most methods assume that protein evolution proceeds in a regular fashion, with the inferred tree of sequences providing a good estimation of the evolutionary process. We investigated the combined HMMER search results from random alignment subsets (with three sequences each) drawn from the parent alignment (Rand-shuffle algorithm), using the SCOP structural classification to determine true similarities. At false-positive rates of 5%, the Rand-shuffle algorithm improved HMMER's sensitivity, with a 37.5% greater sensitivity compared with HMMER alone, when easily identified similarities (identifiable by BLAST) were excluded from consideration. An extension of the Rand-shuffle algorithm (Ali-shuffle) weighted towards more informative sequence subsets. This approach improved the performance over HMMER alone and PSI-BLAST, particularly at higher false-positive rates. The improvements in performance of these sequence sub-sampling methods may reflect lower sensitivity to alignment error and irregular evolutionary patterns. The Ali-shuffle and Rand-shuffle sequence homology search programs are available by request from the authors.     

Scrotal cooling increases rectal temperature in man

The aim of this study was to evaluate the effect of scrotal cooling on rectal temperature in man. Pilot studies suggested that immersing the scrotum in a 30 degrees C water bath increased rectal temperature, but immersing the scrotum in a 0 degree C water bath did not. Six healthy young men immersed their scrotums in a 35 degrees C water bath for 11 min followed by 21 min at 30 degrees C. Rectal temperature rose by 0.38 +/- 0.04 degrees C (P < 0.01) in response to the 30 degrees C water bath. Repetition of the study by immersing the hands instead of the scrotum in the water bath had no effect on rectal temperature. The scrotum appears to play a role in human temperature regulation.     

Effect of hypoxic breathing on cutaneous temperature recovery in man

Effect of hypoxia (12% O₂) on skin temperature recovery was studied on healthy young men. Forty male volunteers free of any respiratory disorder were randomly selected to participate in the study. Skin temperature, peripheral blood flow, heart rate and end expiratoryPO₂ andPCO₂ were measured. During hyoxic ventilation the peripheral blood flow was reduced and a corresponding drop in skin temperature occurred. This was partly due to hyperventilation associated with hypoxic ventilation. The recovery of skin temperature after cooling the hand for 2 min in cold water (10–12° C) took 5.5±0.1 min during normal air breathing; during hypoxic ventilation even after 9.1±0.3 min when the skin temperature recovery curve plateaued, the skin temperature remained about 2° C below control. The results of the present investigation indicate that hypoxia interferes with the normal functioning of the thermoregulatory mechanism in man. Hyperventilation associated with hypoxic ventilation is also partly responsible for incomplete recovery of skin temperature.