Predicting first professional M.B.B.S. examination score from the results of H.S.C. examination

In a retrospective study carried out in Chittagong Medical College the results of HSC and First-Professional MBBS examination of 725 students were analysed. It was concluded from the analysis that if standard of HSC examination is well maintained the results of the said examination correlates well with students' performance in the First Professional MBBS examination. An analysis of admission into Chittagong Medical College in past 20 academic sessions has been made which shows that an increasing number of students securing high marks in HSC are being admitted into Medical College during recent years. The marking standard of HSC examination has however remained fairly uniform over the years except during early post-liberation period.

Diarrhoeal disease in Bangladesh: epidemiology, mortality averted and costs at a rural treatment centre

The basic epidemiology of acute diarrhoeal disease seen at a rural Bangladesh hospital in 1975 is reviewed. V. cholerae 01 was isolated from 28% of 1 964 patients. Significant differences in hospitalisation rates were observed between males and females in several age groups. Overall hospital case fatality was 9/1000 cases. We estimate that approximately a quarter to half of the hospitalised patients would have died had no rehydration therapy been available. The region's total mortality was reduced by approximately 7%-15%, at a cost of United States $0.14 per capita. Mortality from acute diarrhoeal diseases was greatly reduced for all age groups, and total mortality and mortality from all diarrhoeal diseases were particularly reduced for young children and young adults. Rehydration therapy used in a field hospital was apparently highly effective in reducing general mortality and mortality from acute diarrhoeal diseases.

[Experimental studies on cardiopulmonary relation under hypoxia, hypercapnia and airway obstruction in dog (author's transl)]

On 18 dogs the effects of hypoxia (12, 10, 7.5% O2) and hypoxia and hypercapnia (10% O2 + 5, 7.5, 11% CO2) on breathing, pulmonary vascular resistance, cardiac output and on the arterial and venous oxygen pressure were investigated. The relationship between arterial oxygen pressure to Pap as to vascular resistance is not in the mean linear. There are good, bad and nearly nonresponders in respect to the vascular resistance on the dogs. Therefore, calculation and evaluation of mean values are less helpful. A similar variation on men could help to understand also better the large scatter which is always shown on correlations between PO2a : Pap or PO2a : vascular resistance. Also the different pattern of the V/Q relationship may be influenced by the amount of the vascular response to local alveolar hypoxia. An increase of PCO/a potentiates the local vasoconstrictor effect of hypoxia. Mainly this was seen in the range between hypocapnia and moderate rates of hypercapnia. Hypoxia shows an increase of breathing frequency, hypercapnia shows and increase in tidal volume. Also under hypercapnia there are nonresponders and better responders in response to the vascular resistance in the lung circulation. Mechanical airway obstruction is followed by an increase of tidal volume; obstruction caused by acetylcholine is followed by a decrease of tidal volume and an increase of breathing frequency. Changes in the arterial blood gases are caused by changes in the ventilation perfusion relationship only under acetylcholine obstruction. Influences on the lung circulation by the airway obstruction under these experimental conditions as direct effects are small or not existent.

Mechanism of controlling residual volume and emptying rate of the lung in young and elderly healthy subjects

The mechanisms of controlling residual volume and lung emptying in different ages have been examined. Elastic bandage was wrapped around the abdomen, chest and shoulder (chest strapping). The measurements of various lung volumes and airway resistance were performed with and without chest strapping. Reduction in all lung volumes including residual volume (-12%) and light increase in airway resistance were obtained in subjects below 25 years with chest strapping, whereas residual volumes were higher (+ 17%, + 12%) under chest strapping in subjects between 35 and 50 years and > 60 years of age, respectively. The airway resistance was also considerably higher in these two groups. A decrease in residual volume points to the fact that the major controlling mechanism of residual volume lies in the chest wall. Chest strapping removes the outward force on the airways, enhances their closure, and traps more air, which increases residual volume. This means that the limitation of emptying lies in the airways in advanced age (> 34 years).

Tracheal contractility and flow resistance in anesthetized dogs with and without vagal block

The study was carried out on 8 boxer dogs in three groups. They were anesthetized, intubated and breathed spontaneously. The animals were exposed to inhalative acetylcholine (ACH) aerosol, mechanical stimulus to the bronchial tree, intrabronchial and intravenous application of ACH solution. Dynamic elasticity, lung resistance, tracheal resistance and breathing rates were determined. A special method was used for recording tracheal activity in spontaneously breathing animals and noted as tracheal pressure. Those parameters were noted before and after partial blocking of the cervical vagus nerves on both sides. Bilateral vagal block entirely prevented the response produced by mechanical irritation and intrabronchial ACH. Inhalative and intravenous ACH produced significantly less response after vagal block, but certain residues remained. It is concluded that mechanical irritation works entirely through the reflex path, but ACH mostly follows the reflex path a little on the smooth muscle directly.

[Age-dependent mechanical properties of the lung (author's transl)]

Capacity resistance breaking and volume resistance breaking were determined in normal subjects divided into three groups according to their age. There was a statistically significant age dependence with regard to both values. At a higher age, capacity resistance breaking increases in the respiratory tract already above the end-expiratory intrathoracic gas volume. There is a clear-cut age-dependent narrowing of the ventilatory reserve. This points to a relationship to "senile emphysema". It is probable that the premature loss of individual bronchi is a factor in the abnormal clearing mechanism of the elderly lung.

Role of spreading-factor (hyaluronidase) on bronchial response to acetylcholine challenge in dog

Patients with non-specific chronic lung diseases are very sensitive against external challenge. Experiments in human volunteers and in animals it has been shown that many substances can make bronchial system hyperreactive without causing any direct effect. The mechanisms involve in the process of hyperreactive bronchial system are, so far, not clear. It is conceived in this study that membrane permeability might play an important role in this process. This possibility has been studied in anesthetized dogs by subjecting them to hyaluronidase aerosol. This enzyme is supposed to change the membrane permeability by acting on the ground substance. The animals were first challenged with acetylcholine to obtain the basic responsiveness. Then the animals were subjected to hyaluronidase aerosol and challenged with acetylcholine again. Results confirm the hypotheses that membrane permeability plays an important role in hyperreactive bronchial system.

Respiratory damage caused by long-term inhalation of high concentration of sulphur-dioxide in dogs

It has been tried in this study to produce chronic obstructive bronchitis in dogs by exposing them to high concentrations of SO2. The study was extended to 175 days and during that period the animals were exposed to 300-500 ppm SO2 for a total of 435 h. None of the three dogs developed serious respiratory damage. Most of the symptoms were transitory. Histological examinations showed increased number of goblet cells in trachea, main- and lobar bronchi and a slight alteration of the bronchial glands.

[Airway resistance and lung volumes (author's transl)]

Whole-body plethysmography for measuring airway resistance and intrathoracic gas volume is a valuable tool for diagnosing pulmonary and airway functions. It is desirable to know momentary airway resistance in the course of a forced expiration and vital capacity in relation to predicted and actual thoracic gas volume as well as predicted and actual total capacity. This is a reliable means of discovering limitations of lung ventilation despite normal airway resistance during normal ventilation. With a computer and plotter attached to a whole-body plethysmograph such volume-airway resistance curves can be rapidly and well reproduced without stressing the test person. In addition, it also makes it possible to measure routinely the volume resistance breaking point (largely comparable to "closing capacity") even in ill patients.

Mechanism of increased tracheo-bronchial response to inhalative acetylcholine aerosol in pulmonary vascular congestion and unilateral pulmonary artery occlusion

The study was carried out in anesthetized, intubated and spontaneously breathing dogs. The aim of this study was to examine the responsiveness of the tracheo-bronchial system to inhalative ACh. It was considered that any change in ACh-sensitivity signifies the involvement of receptors in the lung itself. Increased pressure in the right heart and main pulmonary artery did not affect the ACh-sensitivity. Whereas, the sustained pulmonary vascular congestion produced by blocking the ascending aorta or by glass bead embolism provoked greater ACh-sensitivity. Increased ACh-sensitivity was also observed in unilateral pulmonary artery occlusion. ACh-sensitivity was greater in the later part of occlusion or vascular congestion and persisted even after the occlusion or block was withdrawn. It is concluded that the increased ACh-sensitivities in pulmonary vascular congestion and in unilateral pulmonary artery occlusion are due to the formation of edema and atelectasis respectively. Anyway, the disturbance of the metabolism of the receptor cells around the small vessels of the lung circulation seems to be essential.

Relationship between pulmonary embolism, airway obstruction and hypersensitivity of the airways in dogs: influence of partial vagus nerve blockade

Experiments in dogs showed an increase in deltaPoes/100 ml TV after embolization which returns to normal after blocking the vagus nerves, indicating an increase in airway resistance. A marked sensitization to ACh inhalation by embolism with both blood clots and glass beads was demonstrated. This hypersensitivity is vagus-dependent.

[Reaction of the cardio-respiratory-system following acetylcholine inhalation and the dependency from the body position on anaesthetised dogs (author's transl)]

The bronchomotoric reaction following ACH-aerosol in low concentrations is dependend on the position of the body on dogs. Up till one maximal reaction the increase of the airway resistance is always stronger in the lateral position. Nevertheless the breathing minute volume is constant. Concentration reaction curves will be shown. Arterial blood gases, heart rate, and pressure in the arteria femoralis were also measured. The different strongness of the reaction following ACH-inhalation will be caused by the predominantely unilateral ventilation of the animals in the lateral position.

Effect of unilateral vagus blockade on antigen-induced airway obstruction

Respiratory hypersensitivity and the effect of unilateral vagus blockade on the same, after the use of Ascaris extract aerosol, are studied in three boxer dogs with spontaneous reactivity to this aerosol. The dogs were exposed initially to Ascaris extract aerosol, and this exposure was repeated after unilateral vagus blockade and after its lavage. The principal parameters, deltaPoes (mm Hg)/100 ml TV, are given as a measurement of airway flow resistance and respiratory rates. The spontaneous respiratory distress observed in all the animals after exposure to the mentioned aerosol was avoided with unilateral blockade of the nervus vagus.

Differential diagnosis of ventilatory disorders with the help of volume/flow diagram

Volume/flow (V/v) diagrams obtained from 82 healthy and pulmonary diseased subjects were analyzed. A formula had been worked out on the basis of determined slow vital capacity, for the calculation of maximum forced expiratory flow (VEmax). The expiratory volume/flow curves were used for the computation of lung conpliance (C1). These calculated values of VEmax and C1 were highly correlated to the measured values. It is concluded that these calculated values would provide a good index for the preliminary differential diagnosis of the pulmonary disorders.

Antigen-induced airway obstruction and the influence of vagus blockade

Respiratory hypersensitivity to Ascaris antigens is carried out on 9 dogs. The participation of vagus reflex on this respiratory distress is studied in 4 of these dogs. The dogs were exposed initially to Ascaris aerosol, then to egg albumin and NaCl aerosol for control, and once more to Ascaris aerosol after bilateral vagi blockade and lavage, respectively. The principal parameters studied were deltaPoes (mm Hg)/100 ml TV as a measurement of flow resistance in the airways, and respiratory rates (Poes=changes of oesphagus pressure; TV=tidal volume). All the animals presented a significant respiratory distress with Ascaris aerosol, which could be clearly avoided with the central bilateral blockade of nervus vagus.

Effect of ascaris extract applied intravenously, on segment bronchus and the influence of ipsilateral vagus blockade

Respiratory hypersensitivity and systemic effects after local application of Ascaris suum extract on the segmental bronchus and after its intravenous infusion are studied on four boxer dogs. Influence of ipsilateral vagus blockade on the respiratory hyperreactivity after intrabronchial application of ascaris was also investigated on the same dogs. Ascaris extract was applied in liquid form directly through a catheter into the right segmental bronchus. Egg albumin was applied in the same way for control. Local application of ascaris was repeated after ipsilateral central vagus blockade and once more after recovering vagus effect by lavage. At the end of the experiments ascaris extract was infused intravenously. The parameters studied were: deltaP(oes) mm Hg/100 ml TV (as a measurement of flow resistance in the airways), respiratory rates, arterial blood gases and pH, heart frequency, systemic blood pressure and histamine concentration per milliliter of plasma. All the animals presented a remarkable respiratory distress with local ascaris application, which could be clearly avoided with ipsilateral central vagus blockade. This respiratory hyperreactivity was not observed after intravenous infusion of ascaris extract, but a significant systemic effect, which was not the case after local application, could be observed.

An outbreak of dysentery caused by Shigella dysenteriae type 1 on a coral island in the Bay of Bengal

An epidemic of severe dysentery occurred on St. Martin Island in the Bay of Bengal at a time when the island, with a population of 1,318, was isolated from the mainland because of the monsoon season. There were 434 cases and 28 deaths within a three-month period. Mortality (2%) was limited to the very young and the elderly. Shigella dysenteriae type 1 (Shiga bacillus) was isolated from 12 of 65 rectal swab specimens. All strains gave similar biochemical reactions and were resistant to tetracycline, chloramphenicol, streptomycin, and the sulfonamides but were sensitive to ampicillin, kanamycin, and gentamicin. No other organism was implicated in the outbreak. The disease disappeared from the island after institution of chlorination of the sources of drinking water and effective treatment of patients.

[Local oversensitivity of sensoric receptors as cause of reflectoric airway obstruction (author's transl)]

The effect of local intratracheal, intrabronchial, and intravenous application of histamine, has been studied in dogs. Control studies are also carried out with saline. There is an increase in intrathoracic pressure per 100 ml of tidal volume due to locally applied histamine. This change is considered as the measure of bronchoconstriction. There is also a significant change in the bronchial sensitivity to acetylcholine inhalation. The intravenous application of the same quantity of histamine produces very little change in the bronchial sensitivity though it has produced strong and prolonged circulatory effect and even transitory respiratory arrest. The application of saline produces no change. It is concluded that the local chemical stimulus can sensitize the whole respiratory system and produces greater bronchconstriction involving some reflex path.