Effect of the nasal airflow inducing manoeuvre on olfaction and quality of life after laryngectomy.

OBJECTIVE: To assess the effectiveness of the nasal airflow inducing manoeuvre or 'polite yawn' technique in improving olfaction and quality of life in laryngectomised patients. METHODS: Using a prospective study design, 42 patients scheduled to undergo laryngectomy at a tertiary care centre were subjected to olfaction testing before surgery and two weeks following the surgery. The nasal airflow inducing manoeuvre was taught, and the olfaction test was repeated with the patient performing the nasal airflow inducing manoeuvre. Quality of life was assessed using the Appetite, Hunger and Sensory Perception questionnaire with calculation of scores after the patient had learnt the nasal airflow inducing manoeuvre. RESULTS: There was a significant reduction in the composite olfaction score, from a mean (standard deviation) baseline value of 4.01 (1.39) to 0.44 (0.51), two weeks after surgery (p < 0.001). After practising the nasal airflow inducing manoeuvre, the olfaction scores increased to 3.05 (1.32) (p < 0.001). Appetite, Hunger and Sensory Perception questionnaire scores ranged from 52 to 110 (normal range, 29-145), suggesting an improvement in the quality of life of patients. CONCLUSION: The nasal airflow inducing manoeuvre, an inexpensive, simple, patient-friendly manoeuvre, can be used in the olfaction rehabilitation of patients undergoing laryngectomy.

Irradiance dependency of UV-A induced phase shifts in the locomotor activity rhythm of the field mouse Mus booduga.

In the nocturnal field mouse Mus booduga, the responsiveness of the circadian system to UV-A light of 2.5 W/m2 and 30 minutes duration is known to be phase dependent. The results of our experiments indicate that the phase shifts evoked by UV-A at the two phases, CT14 (circadian time 14) and CT20 increases nonlinearly with irradiance.

Effects of restricted feeding cycle on the locomotor activity rhythm in the mouse Mus booduga.

The effect of restricted feeding (RF) cycles on the circadian locomotor activity rhythm was studied in the nocturnal field mouse Mus booduga. Mice were presented with a 2-h meal schedule every 24 h in continuous darkness (DD), in continuous light (LL), and in a light-dark (LD) cycle. Additionally, in DD, two groups of mice were subjected to RF cycles of periodicities 22 (T22) and 26 h (T26), respectively, in order to assess the limits of entrainment. The T22 and T26 RF cycles failed to produce any entrainment of the locomotor activity rhythm, whereas some of the animals that had a free-running period (tau) close to 24 h showed stable entrainment or "relative coordination" to daily (T24) RF cycle. In LD, the locomotor activity rhythm phase advanced under the influence of the daily RF cycle when the food presentation preceded the light to dark (L to D) transition by 5-6 h. However, when the timing of food presented in the RF cycle coincided with the L to D transition, locomotor activity rhythm dissociated into two components. Some of the mice whose locomotor activity rhythm disappeared in LL showed prominent meal-AA. These results suggest that RF modifies the expression of the light-entrainable pacemaker (LEP) directly and also that in the absence of the expression of the LEP, RF can induce meal-AA.

In the field mouse Mus booduga melatonin phase response curves (PRCs) have a different time course and wave form relative to light PRC.

The phase shifting effects of the pineal hormone melatonin on the circadian locomotor activity rhythm of the field mouse. Mus booduga was examined at various phases of the circadian cycle using single melatonin injections of two concentrations (10 mg/kg, high dose; and 1 mg/kg, low dose) and two phase response curves (PRCs) were constructed. A single dose of melatonin administered during the early subjective day evoked maximum phase delays, and during the late subjective night evoked phase advances in the locomotor activity rhythm. Other phases of the circadian cycle also responded to melatonin. The interval between circadian time 19 (CT19) and CT2 of the high dose melatonin PRC is marked by significant phase advances, whereas the interval between CT2 and 19 is marked by significant phase delays. A single dose of melatonin of strength 10 mg/kg was found to evoke phase shifts that were of comparable magnitude to those of the phase shifts evoked by natural daylight pulses. Control animals, treated with 50% dimethyl sulfoxide (DMSO), did not respond with phase shifts significantly greater than zero. Significant differences between the shapes of the two melatonin PRCs exist. Further melatonin PRCs appear to have a different time course and wave form relative to light-induced PRC.

Timely administration of melatonin accelerates reentrainment to phase-shifted light-dark cycles in the field mouse Mus booduga.

The effect of melatonin on the rate of reentrainment after a 6 h phase delay and a 6 h phase advance in the light-dark (LD) cycle was assayed in the nocturnal field mouse Mus booduga. After a phase delay of 6 h in the LD cycle, a single dose of melatonin (1 mg/kg) was administered for three consecutive days at about CT4 (circadian time 4). After a phase advance of 6 h in the LD cycle, melatonin was administered for three consecutive days at about CT22. Melatonin was found to accelerate reentrainment in both cases. Melatonin-treated animals took significantly fewer cycles to reentrain compared to vehicle-treated (50% dimethylsulfoxide [DMSO]) and nontreated control animals.

Relationship between light intensity and phase resetting in a mammalian circadian system.

The light-induced phase-resetting response of the locomotor activity rhythm in the field mouse Mus booduga was studied at two phases of the circadian cycle known to respond to light stimuli of 15 min duration and 1000 lux intensity with maximum advance (at circadian time 20 [CT20]) and maximum delay phase-shifts (at CT15). The phase-shifts evoked by natural daylight stimuli of various illuminations ranging between 0.001 lux and 10,000 lux and lasting 15 min were estimated. The results clearly demonstrate that the relationship between the phase-shifts and the intensities of light stimuli is nonlinear. Furthermore, a single light stimulus of 0.001 lux, or 0.1 lux intensity for a duration of 15 min, administered at CT20, evoked unequivocal responses; phase delays were observed instead of phase advances. The critical intensities needed for light stimuli of 15 min duration to induce saturating response were calculated and were found to be about 100 lux for CT20 and about 500 lux for CT15. These results suggest that a greater intensity of light is required at the phase CT15 to induce a saturating phase shift than is required at a later phase of the circadian cycle (CT20).

Ultraviolet-light-evoked phase shifts in the locomotor activity rhythm of the field mouse Mus booduga.

The circadian rhythm of locomotor activity in the nocturnal field mouse Mus booduga has been monitored after an exposure to ultraviolet-A (UV-A; wavelength between 350 and 400 nm) radiation at various hours of the subject's cycle. The magnitude of the phase shift is used to determine the sensitivity of the circadian pacemaker underlying locomotor activity rhythm. It is observed that UV-A shifts the phase of the locomotor activity rhythm in a phase-dependent manner. A phase response curve (PRC) is constructed to depict the time course and waveform of the basic oscillator's sensitivity to UV-A radiation. The UV-A PRC qualitatively resembles the PRC constructed using diffused daylight as stimulus. Furthermore, the phase response characteristics of the circadian pacemaker for UV-A suggest a periodically varying sensitivity to UV-A similar to that to daylight.

Parturition and mother-infant relations in the Indian false vampire bat Megaderma lyra.

The onset and duration of parturition were studied in Megaderma lyra for two successive periods during the years 1989 and 1990. The period of parturition fell between January and May in 1989, and between March and May in 1990. This change in the length of parturition period was not due to variations in the pattern of rainfall when prey items are abundant. The young M. lyra clung continuously for 5-7 days from birth to their mothers whose foraging modality seemed unaffected. Grown-up infants were left at a temple roost while the mother bats foraged. On a few occasions, mothers and infants were also seen at different `night roosts' found close to the temple roost. In all stages of nursing, the lactating mothers had two distinct bouts of foraging, one immediately following emergence (at dusk) and the other during their return (at predawn hours) to their main roost. The mean lactation period in M. lyra was approximately 70 days.

Relationship between free-running period and minimum tolerable light pulse interval of skeleton photoperiods in field mice Mus booduga.

The entrainment of the circadian rhythm of locomotor activity was studied in the field mouse Mus booduga in order to examine the relationship between the free-running period (tau) and minimum tolerable light pulse interval of the skeleton photoperiods. The animals were entrained under three different light/dark (LD) schedules, each out of phase with the other. They were then subjected to various skeleton photoperiods created by two repeated light pulses (LPs) interrupting darkness. Animals that selected the shorter interval between the LPs as their "subjective night" had significantly shorter tau (23.13 +/- 0.38 h) as compared to those that selected the longer dark interval as subjective night (tau = 23.87 +/- 0.18 h). When the longer dark interval was 12 h, animals selecting that interval as their subjective night included both long-tau and short-tau individuals. When both intervals of darkness were of equal duration, no difference in the selection of subjective night was seen between short and long-tau animals. When the "dusk" LP for the animals that selected the longer dark interval as subjective night was advanced by 2 h to create a new skeleton photoperiod, the number of transient cycles appearing before steady-state entrainment was found to depend on the duration of the photoperiods. When the night defined by the two LPs was reduced below 6h, a dramatic "phase jump" in the activity rhythm was observed, and the initial phase relationship was restored after a relaxation in the night duration. We observed considerable interindividual variation in the "minimum tolerable light pulse interval of skeleton photoperiods," which we suggest may be due to the observed variation in tau among individuals.

Responses of the circadian locomotor activity rhythm of Mus booduga to shifts in LD schedules.

The responses of the field mouse Mus booduga to shifts in schedules of LD cycles were monitored and the results were interpreted with the help of a PRC constructed for the same species. The results reveal that, M. booduga reentrained faster with a lesser number of transients after delay shifts than advance shifts, thus exhibiting "asymmetry effect." A positive correlation was observed between the number of transients and the number of hours of shift. In most of the shifts, the sign of the transients (negative for delaying transients and positive for advancing transients) coincided with the direction of the shift. Interestingly, 11 and 12 h of advance shifting resulted in delaying transients. An 11-h advance shift can also be interpreted as a 13-h delay. Reentrainment through delaying transients is faster as compared to reentrainment through advancing transients. Thus, this animal might have taken a "shorter route," as proved by the fact that an 11-h advance shift has evoked delaying transients. But a 13-h advance shift evoked only advancing transients. This prompts us to speculate that there may be a "phase jump" in M. booduga. Further, irrespective of whether L or D has been doubled in a 12-h shift, both evoked only delaying transients.

Diazepam modulates the period of locomotor rhythm in mice (Mus booduga) and attenuates light-induced phase advances.

Experiments were carried out on the continuous action of diazepam (benzodiazepine) offered through drinking water in 2% ethanol on psi and tau of the activity rhythms under LD (12:12) and DD conditions. Under entraining conditions diazepam failed to evoke striking changes in psi. On the other hand, under free-running conditions period-lengthening and period-shortening effects were observed. Further experiments conducted on the continuous effect of diazepam on light pulse evoked phase shifts revealed that phase advances were attenuated significantly in diazepam-treated animals at CT 20 and 24. These results were discussed with regard to the action of diazepam on the light sensitivity of the circadian pacemaker.

Green light evokes maximum phase shifts in the locomotor activity rhythm of the field mouse Mus booduga.

The effect of pulses of different monochromatic light wavelengths was investigated on the circadian locomotor activity rhythm of the tropical rodent Mus booduga. Blue (480 nm), green (549 nm) and red (649 nm) light were used for pulses at circadian time (CT) 14 and 20, the maximum delay and advance eliciting phases of the white light phase response curve (PRC). All three wavelengths evoked qualitatively similar responses in terms of the signs of the phase shifts. Contrary to the results obtained in rabbits and bats, M. Booduga does not exhibit differential responses to different light wavelengths at various phases. This prompts us to speculate on the existence of a single class of photoreceptors for all light wavelengths. The responses of these animals to three different energy levels (5, 25 and 50 microW cm2) of these light wavelengths were also studied and these showed quantitative differences. Green light evoked larger phase shifts in terms of both delays and advances compared with red light (P < 0.1 at both CTs). However, it failed to exhibit an energy-dependent increase in the magnitude of the phase shifts. In contrast, red light evoked an energy-dependent increase in the magnitude of the phase shifts of both CT 14 and CT 20 and blue light at CT 14 alone. It is speculated that the threshold level for perceiving green light may be lower than the energy levels used and hence saturation would have been reached at 5 microW cm-2. For red light, it is possible that this threshold is at a much higher level. This explains the failure to exhibit an energy-dependent increase by green light and the systematic increase by red light.

Seasonality in the flight activity of the tropical bat Rhinopoma hardwickei under natural photoperiod.

The activity cycle of a colony of about 1500 bats Rhinopoma hardwickei was studied in 1978-1979 in Madurai, India. Variations in the times of emergence of foraging paralleled variations in sunset and return to the roosting paralleled sunrise. The releasing stimulus for departure of the first outflyer on clear evenings is the crossing of a lower threshold value of its relative decrease. Return to the roost usually occurs at a lower light intensity than the departure. In summer the nightly rate of emergence is relatively higher than in winter. The seasonal changes of phase angle differences of onset (Ψ0) and end (Ψe) of activities are roughly mirror images. The time of midpoint of foraging activity however, stays relatively constant.

Differential effects of pinealectomy on circadian rhythms of feeding and perch hopping in the European starling.

To study the effects of pinealectomy on the circadian rhythms of locomotor activity and feeding. European starlings (Sturnus vulgaris) were held in constant light (0.2 lux and 200 lux) and under constant temperature conditions. Locomotor activity was measured by means of perches with microswitches mounted underneath, and feeding with an infrared photocell system at the feeder. Pinealectomy consistently led to disturbances in perch-hopping rhythms and often to a complete loss of rhythmicity as revealed by periodogram analysis. In some birds, perch-hopping rhythms recovered following a period of initial arrhythmicity. When a perch-hopping rhythm was present, its period was usually shorter than it had been before pinealectomy. In contrast to its effects on perch hopping, pinealectomy had no effect on the persistence of feeding rhythmicity, although its period, like that of the hopping rhythm, decreased after this operation. These results support the hypothesis derived from previous studies that the circadian organization of feeding is different from that of perch hopping. Different circadian pacemakers may be involved, but other models may possibly explain the data just as well.

Effect of lithium chloride on the circadian rhythm in the flight activity of the microchiropteran bat, Taphozous melanopogon.

We have performed experiments on the influence of Li+ offered through drinking water i) on the period length (tau) of the rhythm in the flight of bats under LL and ii) on phase angles during entrainment under LD cycles. Bats subject to entrainment exhibited no qualitative and quantitative change in psi values after Li+ treatment. In contrast the ingestion of Li ions by bats under free-running conditions shortens the tau of the bat rhythm by an amount that is a function of period length prior to ingestion. Tau is, thus homeostatically conserved in the face of Li administration in bats.

Influence of fusaric acid on circadian leaf movements of the cotton plant, Gossypium hirsutum.

The cotton plant, Gossypium hirsutum L. (cv. Lakshmi) exhibits circadian leaf movements. Fusaric acid (5-n butyl pyridine 2-carboxylic acid), an in vivo toxin shown to be produced during the pathogenesis of the wilt disease in cotton, causes phase shifts of the leaf movement rhythm that varied in degree and magnitude as a function of the treated phases. The data support the hypothesis that membranes play a vital role as a pacemaker in circadian rhythms.

'Rigid' internal timing in the circadian rhythm of flight activity in a tropical bat.

The timing of the emergence activity of a colony of the bat Taphozous melanopogon occupying a cave environment in Madurai (lat. 9°58' N, long. 78°10' E) and consisting of approximately 150-180 animals of both sexes was studies at 10-day intervals for one year. Even though the time of sunset during the eyar varied over a range of 41 min, the bats displayed an astonishingly 'rigid' time of emergence that was restricted to a narrow 'gate' of 16 min from 18:25 to 18:41 h. The timing of the termination of the activity was less precise in all seasons. Light/dark cycles are clearly the Zeitgeber. Even so, the bats began flying when it was very dark (0.1 lx) during shorter days, and they flew out as the sun was disappearing in the evening horizon (50 or more lx) during long days. Evidently there is no invariant, 'fixed' lower threshold intensity that uniformly elicits the onset of activity throughout the year as reported earlier by other authors (Aschoff, 1969; Erkert, 1974). It is proposed that the bats undergo a systematic seasonal shift in the threshold sensitivity to light in response to the photic Zeitgeber of the environment. The result is a remarkable precision in terms of the hours of the civil/calendar day in the emergence of Taphozous melanopogon.