Biomedical subjects
Publications and source records attributed to H Merchant.
Bilioma secondary to choledocholithiasis is rare. We report a patient in whom a large common bile duct stone was responsible for leak from the infraduodenal segment of the bile duct. Choledochotomy with extraction of stone followed by T-tube drainage of the bile duct and evacuation of the bilioma resulted in complete recovery.
We lesioned the right primary somatic sensory (S1) cortex in two monkeys trained to categorize the speed of moving tactile stimuli. Animals performed the task by pressing with the right hand one of two target switches to indicate whether the speed of a probe moving across the glabrous skin of the left hand was low or high. Sensory performance was evaluated with psychometric techniques and motor behavior was monitored by measuring the reaction (RT) and movement (MT) times before the experiment and throughout the 60 days after the ablation of SI cortex. After the lesion, there was a slight increase in the RTs but no change in the MTs, indicating that removal of SI cortex did not affect the animals' capacity to detect the stimuli. However, monkeys lost their ability to categorize the stimulus speeds. This effect was observed from the 1st day after the lesion until the end of the study. We conclude that somatosensory areas outside SI can by themselves process tactile information in a limited way and that the extraction of higher-order features that takes place during the categorization task requires the intervention of SI cortex.
In this paper we describe a type of neuron of the medial premotor cortex (MPC) that discharged differentially during a categorization task and reflected in their activity whether the speed of a tactile stimulus was low or high. The activity of these neurons was recorded in the MPC contralateral (right MPC, n = 88) and ipsilateral (left MPC, n = 103) to the stimulated hand of four monkeys performing this somesthetic task. Animals performed the task by pressing with the right hand one of two target switches to indicate whether the speed of probe movement across the skin of the left hand was low or high. Differential responses of MPC neurons occurred during the stimulus and reaction time period. We used an analysis based on signal detection theory to determine whether these differential responses were associated with the animal's decision. According to this analysis, 104 of the 191 neurons (right MPC, n = 48; left MPC, n = 56) coded the categorization of the stimulus speeds (categorical neurons). In a light instruction task, we tested the possibility that the categorical neurons (n = 71) were associated with the intention to press, or with the trajectory of the hand to one of the two target switches used to indicate categorization. In this situation, each trial began as in the somesthetic categorization task, but one of the two target switches was illuminated beginning with the skin indentation, continued during the delay period and turned off when the probe was lifted off from the skin. This condition instructed the animal which target switch was required to be pressed for reward. Very few neurons (14 of 71) maintained their differential responses observed in the categorization task. Some categorical neurons (n = 5) were also studied; the animal categorized the tactile stimulus speeds, but knew in advance whether the stimulus speed was low or high (categorization + light instruction). This was made by illuminating one of the two target switches which was associated with the stimulus speed. The categorical response was considerably attenuated in this condition. Interestingly, during the delay period, these neurons reflected in their activity whether the stimulus was low or high. A number of the categorical MPC neurons (n = 30) were studied when the same set of stimuli, used in the categorization, were delivered passively. None of these neurons responded in this condition. These results suggest that the MPC, apart from its well-known role in motor behavior, is also involved in the animal's decision during the execution of this learned somesthetic task.
In a prospective 6-month study, sonographic diagnosis of biliary ascariasis was made in 14 patients; in nine patients, the diagnosis was confirmed by endoscopic retrograde cholangiopancreatography and bile analysis, while in five patients, confirmation was obtained by proven intestinal infestation. No false-positive or false-negative cases were encountered. Ascariasis of the biliary tract was seen on ultrasound as echogenic, non-shadowing images, either as single or multiple strips, with visualization of the digestive tract of the worm as an anechoic inner tube, or as amorphous fragments. Follow-up sonograms helped in detection of worm expulsion following medical therapy in five patients, while endoscopic extraction of the worm was performed in four patients. In three patients, disappearance of the worm from the biliary tract was noted following a therapeutic sphincterotomy, and two patients detected to have a worm within the gall-bladder were operated on. In all patients, serial sonograms revealed disappearance of the worm, and the regression of biliary tract dilatation.
We used psychometric techniques and neurophysiological recordings to study the role of the putamen in somesthetic perception. Four monkeys were trained to categorize the speed of moving tactile stimuli. Animals performed a task in which one of two target switches had to be pressed with the right hand to indicate whether the speed of probe movement across the glabrous skin of the left, restrained hand was low or high. During the task we recorded the activity of neurons in the putamen contralateral (right) and ipsilateral (left) to the stimulated hand. We found different types of neuronal responses, all present in the right and left putamen. Some neurons responded during the stimulus period, others responded during the hand-arm movement used to indicate categorization, and others responded during both of these periods. The responses of many neurons did not vary either with the speed of the stimuli or in relation to the categorization process. In contrast, neurons of a particular type responded differentially: their activity reflected whether stimulus speed was low or high. These differential responses occurred during the stimulus and hand-arm motion periods. A number of the nondifferential and differential neurons were studied when the same stimuli used in the categorization task were delivered passively. Few neurons with nondifferential discharges, and none of the differential neurons, responded in this condition. In a visually cued control task we studied the possibility that the differential responses were associated with the intention to press or with the trajectory of the hand to one of the target switches. In this condition, a light turned on instructed the animal which target switch to press for a reward. Very few neurons in both hemispheres maintained the differential responses observed during the categorization task. Those neurons that discharged selectively for low or high speeds were analyzed quantitatively to produce a measure comparable with the psychometric function. The thresholds of the resulting neurometric curves for the neuronal populations were very similar to the psychometric thresholds. The activity of a large fraction of these neurons could be used to accurately predict whether the stimulus speed was low or high. The results indicate that the putamen, both contralateral and ipsilateral to the stimulated hand, contains neurons that discharge in response to the somesthetic stimuli during the categorization task. Those neurons that respond irrespective of the stimulus speed appear to be involved in the general sensorimotor behavior of the animal during the execution of the task. The results suggest that the putamen may play a role in bimanual tasks. The recording of neurons in the right and left putamen whose activities correlate with the speed categories suggests that this region of the basal ganglia, in addition to its role in motor functions, is also involved in the animal's decision process.
We used psychometric techniques to study the sensorimotor performance of four monkeys trained to classify the speed of moving tactile stimuli. Animals performed the task by pressing one of two target switches to indicate whether the speed of probe movement across the glabrous skin of the hand was low or high. Psychometric curves indicated that animals classified the stimulus speeds irrespective of which finger was stimulated, traverse distance and direction. The mean values of the reaction (RT) and movement (MT) times during the correct categorization of low and high stimulus speeds were similar. However, a slight increase was detected in the mean values of the RT during the incorrect categorization but not in the MT. During the task, activity of single neurones (n = 45) was recorded in primary somatic sensory (SI) cortex. The results indicate that a class of neurones (n = 12) of SI cortex increased their impulse rates as a function of the stimulus speeds. However, the magnitude of their responses was similar during the correct and incorrect categorizations of stimuli. The same neurones also responded when the same set of stimuli used in the categorization task were delivered passively. Neurones of SI cortex responded with a latency of 25.8 +/- 0.6 ms (+/- s.e.m.) relative to the beginning of the moving tactile stimuli during the categorization task. The same neurones (n = 17) also responded with a similar latency (24.6 +/- 4.0 ms) when the stimuli were delivered passively. These results may suggest that, although this evoked neuronal activity may be important for the perception of the moving tactile stimuli, more central structures associated with SI cortex may determine the performance of this learned somaesthetic task.
We have studied neuronal activity in the putamen of two monkeys trained to discriminate the speed of moving tactile stimuli. Animals pressed one of two target switches to indicate whether the speed of the probe across the skin was low or high. The activity of single neurones was recorded in the putamen ipsilateral to the glabrous skin of the stimulated hand and contralateral to the responding arm. During the task, we recorded neurones in the putamen that showed responses confined exclusively to the stimulus period of all speeds. A second class of putamen neurones responded during the stimulus period but continued discharging during the reaction and movement time period. None of these two classes of putamen neurones discharged when the same set of stimuli were delivered passively. A third class of putamen neurones responded differentially in the discrimination task and predicted whether the speed of the stimulus was low or high. A number of these neurones, which responded differentially during the categorization task, were tested in a light instruction task. This tested the possibility that these differential responses were associated with the intention to move the arm to one of the two target switches. Few neurones responded in this situation. These results indicate that the putamen, in addition to its role in motor regulation, is also involved in higher order aspects of sensory-motor behaviour and in the sensory decision process in this learned somaesthetic task.
The reproductive hormonal profile was evaluated in female rats with experimental nephrotic syndrome induced with a single subcutaneous dose of puromycin aminonucleoside (PAN). Serum concentrations of luteinizing hormone (LH), follicle-stimulating hormone (FSH), progesterone (P4), testosterone and 17 beta-estradiol (E2) were determined sequentially in control and experimental groups on days 1, 3, 7 and 10 after PAN administration. Prolactin levels were also assessed on day 10. In both groups, vaginal smears were taken daily throughout the study to evaluate cyclic histological changes. At the end of the experiment the histological appearance of the ovaries was evaluated by light microscopy. Nephrotic rats had a rapid loss of the estrous cycle starting on day 4, which set them at diestrus. At the same time the hormonal evaluation indicated a gradual decrease in E2, LH and P4 concentrations, starting from days 3, 7 and 10, respectively. No significant changes were noted in FSH or testosterone values. Besides, on day 10, prolactin concentrations remained unmodified. Even though most hormonal levels were found low on day 10, all values except E2 (undetectable) corresponded to the interval reported for the diestrus phase. Likewise, histological examination of ovarian tissue from nephrotic rats showed a considerable increase in the number of atretic follicles. These findings indicate that female rats with nephrotic syndrome develop an important endocrine dysfunction that probably involves steroidogenic tissues (ovary and/or adrenal gland), and suggest the existence of a hypothalamic-hypophyseal impairment.
1. We have studied the neuronal activity in the supplementary motor area (SMA) of two monkeys who categorized the speed of moving tactile stimuli delivered to the glabrous skin of the hand ipsilateral to the site of cortical recording and contralateral to the responding arm. 2. A large number of SMA neurons responded to the stimuli of all speeds (176 of 522) but only when those stimuli controlled behavior. 3. A second class of SMA neurons responded differentially in the categorization task (35 during the stimuli and 51 during the reaction time period) and predicted its outcome. 4. To dissociate the interrupt target switches presses from the tactile categorization responses, sixteen neurons, which responded to the stimuli in all speeds, and 11 neurons, which discharged differentially, were tested in a visual control task. None of these two classes of neurons responded in this situation. 5. It is concluded that the SMA ipsilateral to sensory input and contralateral to the responding arm is involved in the sensory decision process in this somesthetic categorization task.
The effect of specific glycosaminoglycan-hydrolyzing enzymes on the ruthenium red staining of pig spermatozoa was studied. Washed spermatozoa were incubated at 35 degrees C in buffer or with neuraminidase 0.5 units/ml, heparinase 0.2 mg/ml, or chondroitinase ABC 2.0 units/ml. After incubation sperm cells were washed, stained with ruthenium red and studied under the electron microscope. Anionic sites in the surface of untreated spermatozoa follow regularly the plasma membrane, but present are numerous processes constituting what has been defined as the glycocalyx. Neuraminidase did not affect the distribution of ruthenium red on the surface of the spermatozoa, but eliminated almost completely the processes of the glycocalyx. Heparinase caused loss of the ruthenium red-stained sites on the membrane surface of pig spermatozoa with less influence on the dense processes of the glycocalyx. A similar loss of ruthenium red-stained sites was observed with nitrous acid treatment. A striking effect of treatment with chondroitinase ABC was the production of a typical acrosome reaction.
The possibility that partial hydrolysis of glycosaminoglycan-sulfates (GAGs) such as occurs during the last phases of follicular maturation could play some role in the activity of follicular fluid as an inducer of the acrosome reaction was explored. Hydrolysis of follicular fluid GAGs (ff-GAGs) for 30 min with low-pH HNO2 substantially increased (more than 3 times) its capacity to induce the acrosome reaction. This increase was significantly reduced when the time of hydrolysis was either shorter (10 min) or longer (60 min). Partial hydrolysis of spermatozoa GAGs by direct incubation of sperm cells with chondroitinase ABC was also capable of inducing the acrosome reaction.
Magnesium, calcium, and zinc at the concentration of 10 microM are capable of inducing a "true" acrosome reaction in the pig spermatozoa judged by the criteria of the fusion of the acrosome and the plasmatic membrane at the anterior region or the sperm nucleus. The optimal percent of acrosome reaction reached by any of the ions tested as a whole was 50%. When glycosamineglycan sulfate (GAGs) plus 10 microM of Mg++, Ca++, or Zn++ was added, they reach to 70-80% of acrosome reaction. At the electrom microscope, thin sections taken from pig spermatozoa treated with ions, GAGs, or ion + GAGs under optimal experimental conditions revealed the same pattern of acrosomal reaction. Results suggest the important role that divalent cations play in general in the induction of the acrosome reaction and question the so-called essential role of calcium ions.
Follicular fluid from different mammalian species possesses two factors responsible for the induction of capacitation: a sperm-stimulating factor and an acrosomal reaction-inducing factor. The glycosamineglycan-sulfate (GAGs) extracted from pig follicular fluid induce acrosome reaction in pig spermatozoa which exhibit no morphological difference between the GAGs-induced reaction and the natural one. Acrosomal reaction commenced 30 min after the addition of GAGs and depended on GAGs concentration reaching 80% of acrosomal reacted spermatozoa after 6 hr of incubation with 7 mg of GAGs/ml. Chemical composition differs with the chemical data that characterize them as proteoglycans since those we obtained were practically protein free (2%). Another difference resides in the uronic acid content, which is almost twofold higher (59%). Electron microscope observations of the acrosomal reacted spermatozoa revealed that the addition of 10 mg/ml of trypsin soybean inhibitor did not interfere with any of the acrosomal reaction steps. The active capacitating factors may also originate from the follicular fluid released into the genital tract during ovulation.
The addition of heparin to human sperm zinc-depleted nuclei releases DNA template restrictions. Spermatozoa depleted of zinc were assayed for (3H-methyl), thymidine incorporation was observed (27,500 +/- 1,248 dpm of 3H methyl-thymidine). Sperm cells incubated in the presence of 10 mg/ml of soybean trypsin inhibitor shows no effect in sperm nuclear swelling or in the release of DNA template restrictions. This process runs in a parallel fashion to the nuclear swelling induced by heparin, suggesting that swollen nuclei might be the source of DNA template. This was confirmed by autoradiographic studies, since all the sperm cells whose nuclei were judged swollen by morphological criteria also appeared labeled. The fact that there was no need for ATP generating system or of exogenous DNA polymerase emphasized the control role that zinc plays in the physiology of the human spermatozoa.
Zona-free hamster oocytes were incubated in vitro with human spermatozoa treated with heparin for 5, 10, 20, and 30 min. Sperm penetration was observed 2, 4, and 8 h after insemination. Sperm penetration was successful in 40%, 60%, and 69% of the oocytes treated for 10 min with heparin. Feminine and masculine pronuclei were clearly identifiable. In these samples, 80% of the sperm was alive and there was approximately 68% progress motility. Live sperm were observed for up to 24 h. Since glycosamineglycan sulfates are normally present in the ooplasm, zona pellucida, follicular and uterine fluids, this might suggest a direct participation of heparin in human sperm capacitation.
Decondensation of mammalian epididymal spermatozoa nuclei has been induced by exposure of intact spermatozoa to heparin, including those species in which ejaculated sperm were not susceptible to this treatment. This process occurred in the absence of any disulfide bond cleaving reactant. Swelling of caput epididymal spermatozoa nuclei commenced about 30 min after the addition of heparin, reaching 88% in rat, 33% in rabbit, 26% in pig, and 62% in bull of swelled nuclei after 6 hr of incubation at 37 degrees C with 5000 USP of heparin per ml. Corpus epididymal spermatozoa nuclei of rat and rabbit underwent decondensation at 50 degrees C reaching 24% and 22% of swelled nuclei, respectively, after 6 hr of incubation. The nuclei of the sperm cells of pig and bull from this epididymal region remained highly condensed as well as the nuclei of the cauda epididymal spermatozoa of all the species assayed. Electron microscope observations of the caput epididymal spermatozoa nuclei treated with heparin revealed that the chromatin is organized into nuclear bodies joined by a network of cross-linked and branched chromatin fibers in the species studied.
Decondensation of human and sea urchin spermatozoan nuclei has been induced by exposure of intact spermatozoa to glycosamineglycan-sulfate (GAGs) extracted from eggs of the sea urchin. Toxopneustes roseus. Swelling of human spermatozoan nuclei commenced about 60 min after the addition of GAGs and, depending on the extract concentration, the proportion of swollen nuclei reach 90% after 6 h of incubation when 20 mg of GAGs per ml was used. Swelling of sea urchin spermatozoan nuclei could be induced also with GAGs and/or with heparin. Swelling commenced about 10 min after the addition of GAGs/heparin reaching 90-92% after 60 min of incubation with 5 mg GAGs/500 USP heparin per ml. Preincubation of spermatozoa with 10 mg/ml of trypsin soybean inhibitor did not interfere with the swelling action of the GAGs.
The existence in the human spermatozoa membrane of receptorlike functional group for heparin was studied. Incubation of whole spermatozoa with tritiated heparin induced the specific binding of 745 +/- 112 pmol of heparin per 5 x 10(7) sperm cells with an intrinsic association constant KD = 3.6 x 10(-6) M. The specificity of binding was shown by the lack of competence in the binding process of some other glycosaminoglycans used at concentrations 20 x higher than heparin. However, dextran sulfate was a very efficient competitive agent. Autoradiography experiments showed that labeling was almost completely restricted to sperm cells in the process of nuclear decondensation. This technique showed the presence of a high amount of radioactive heparin in the isolated sperm membranes even after several washings. Heparin may participate both in the final part of the capacitation process (acrosome reaction) and in the decondensation of sperm nuclei.