Showing papers by "University of Texas Medical Branch published in 1978"

Intracortical connectivity of architectonic fields in the somatic sensory, motor and parietal cortex of monkeys

Abstract: Anterograde and retrograde transport methods were used to study the corticocortical connectivity of areas 3a, 3b, 1, 2, 5, 4 and 6 of the monkey cerebral cortex. Fields were identified by cytoarchitectonic features and by thalamic connectivity in the same brains. Area 3a was identified by first recording a short latency group I afferent evoked potential. Attempts were made to analyze the data in terms of: (1) routes whereby somatic sensory input might influence the performance of motor cortex neurons; (2) possible multiple representations of the body surface in the component fields of the first somatic sensory area (SI). Apart from vertical interlaminar connections, two types of intracortical connectivity are recognized. The first, regarded as "non-specific," consists of axons spreading out in layers I, III and V-VI from all sides of an injection of isotope; these cross architectonic borders indiscrimininately. They are not unique to the regions studied. The second is formed by axons entering the white matter and re-entering other fields. In these, they terminate in layers I-IV in one or more mediolaterally oriented strips of fairly constant width (0.5--1 mm) and separated by gaps of comparable size. Though there is a broadly systematic topography in these projections, the strips are probably best regarded as representing some feature other than receptive field position. Separate representations are nevertheless implied in area 3b, in areas 1 and 2 (together), in areas 3a and 4 (together) and in area 5; with, in each case, the representations of the digits pointed at the central sulcus. Area 3b is not connected with areas 3a or 4, but projects to a combined areas 1 and 2. Area 1 is reciprocally connected with area 3a and area 2 reciprocally with area 4. The connectivity of area 3a, as conventionally identified, is such that it is probably best regarded not as an entity, but as a part of area 4. Areas identified by others as area 3a should probably be regraded as parts of area 3b. Parts of area 5 that should be more properly considered as area 2, and other parts that receive thalamic input not from the ventrobasal complex but from the lateral nuclear complex and anterior pulvinar, are also interconnected with area 4. More posterior parts of area 5 are connected with laterally placed parts of area 6. A more medial part of area 6, the supplementary motor area, occupies a pivotal position in the sensory-motor cortex, for it receives fibers from areas 3a, 4, 1, 2 and 5 (all parts), and projects back to areas 3a, 4 and 5.

Intracerebral Venous Angioma: Case Report and Review

Abstract: • Only a few cases of angiographically demonstrated and pathologically proved cases of venous angiomas have been published. In contrast to the scarcity of recorded cases of angiographically studied venous angiomas, they are the most common incidentally encountered angiomatous lesions at autopsy. Their angiographic characterization, though highly suggestive, is not pathognomonic. The angiographic characteristics include small radiating veins that drain into a larger transcerebral vein that in turn empties into a dural sinus; blush and early draining veins also may be seen. The differential diagnosis includes telangiectasia, infiltrating glioma, and probably a cavernous angioma. We report an angiographically demonstrated and pathologically proved case of a venous angioma and also review the literature.

Spinal projections from the midbrain in monkey.

Abstract: Neurons descending from the midbrain to the spinal cord in the monkey were identified with the retrograde horseradish peroxidase technique. Beginning in the caudal midbrain and extending anteriorly beneath the superior colliculus, large numbers of neurons of the nucleus cuneiformis and lateral central gray were found to project ipsilaterally to the spinal cord. In the posterolateral superior colliculus, neurons of the intermediate and deep layers, stratum griseum intermediale and stratum griseum profundum, were found to give rise to contralateral projections to the upper cervical spinal segments. An ipsilateral tectospinal projection from the anteromedial part of the collicus may also exist. In the red nucleus, neurons of the magnocellular division were shown to give rise to a somatotopically organized projection to the upper cervical cord and spinal enlargements. No neurons of the parvocellular red nucleus were labeled from the spinal cord. In the anterior midbrain, neurons of the interstitial nucleus of Cajal, nucleus of Darkschewitsch, and the adjacent dorsomedial and ventromedial midbrain tegmentum were found to give rise to an extensive ipsilateral descending spinal projection. Neurons located in various midline nuclei including the supratrochlear nucleus, oculomotor nucleus, Edinger-Westphal nucleus, and the ventral part of the central gray were also labeled from the spinal cord. These findings indicate that the primate midbrain is the origin of an extensive system of descending spinal pathways, some of which are likely to be involved in mediating descending influences involved in complex motor and sensory behavior.

Biological effects of staphylococcal enterotoxin A on human peripheral lymphocytes.

Abstract: The mitogenicity, ability to induce immune interferon, and relationship between interferon synthesis and cell proliferative response were studied using human peripheral lymphocytes stimulated by staphylococcal enterotoxin A (SEA), phytohemagglutinin-P (PHA-P), and concanavalin A (ConA) Maximum cell proliferative responses ([(3)H]thymidine incorporation) and protein synthesis ((14)C-amino acid incorporation) occurred on days 3 and 4, respectively, after stimulation by each of the three mitogens Maximal immune interferon levels were found 3 or 4 days after mitogen stimulation SEA-treated cultures produced approximately three times more interferon than did cultures stimulated with PHA-P or ConA Furthermore, SEA stimulated maximal cell proliferation over a much broader concentration range than did PHA-P and ConA (SEA, 10(-5) to 10(2) mug/ml; PHA-P, 10(1) to 10(2) mug/ml; ConA, 10(1) to 10(15) mug/ml) Interferon was also produced at maximal or near maximal levels over a broad concentration range of SEA (10(-2) to 10(2) mug/ml) Also, we found that inhibition of mitogen-induced DNA and protein synthesis to control levels by mitomycin C or cytosine arabinoside partially reduced interferon production The DNA inhibitor studies indicate that immune interferon synthesis occurs maximally in association with at least some proliferative response and that submaximal levels of interferon production occur in mitogen-treated cultures in the absence of detectable proliferation The ability of SEA to stimulate maximal DNA and immune interferon synthesis at concentrations of 35 x 10(-13) M and 35 x 10(-10) M, respectively, puts it in a potency range similar to that of hormones Thus, SEA may play an important role in gut immunity and Staphylococcus aureus infections at concentrations well below those required for emetic effects

Behavioral sequelae of closed head injury. A quantitative study

Abstract: • We determined the profile of behavioral disturbance in relation to closed head injury of graded severity. Patients with severe injuries, as defined by duration of coma and the presence of neurologic deficit, were differentiated from a group of mildly injured patients by behavioral ratings that reflected cognitive disorganization, emotional withdrawal, and motor retardation. Neurologic measurements of injury related to the severity of behavioral disturbance included hemiparesis, aphasia, and abnormalities on computerized axial tomography. Agitation during the acute phase of injury was also predictive of residual behavioral disturbance. Hemispheric lateralization of the site of greatest injury had no discernible effect on behavioral sequelae.

Differential projections of cat medullary raphe neurons demonstrated by retrograde labelling following spinal cord lesions

Abstract: Neurons of the medullary raphe nuclei in cats were retrogradely labelled following injection of horseradish peroxidase (HRP) into the L6 spinal cord segment. Brainstems were cut in sagittal section to facilitate examination of the rostral-caudal extent of raphe neurons projecting to the spinal cord. Large numbers of HRP-labelled neurons were found in nucleus raphe magnus, nucleus raphe pallidus, and nucleus raphe obscurus (as well as a few neurons in nucleus raphe pontis). Dorsal or ventral hemisections at the T12-L1 level restricted HRP retrograde transport to those pathways within the intact portion of spinal cord, allowing a determination of the part of the cord through which raphe neurons project to the lumbar enlargement. Neurons of nucleus raphe magnus were found to project primarily in dorsolateral fasciculus. A significant number of neurons of nucleus reticularis gigantocellularis also project in dorsolateral fasciculus. Nucleus raphe obscurus neurons were found to project primarily in ventral funiculus, while nucleus raphe pallidus neurons project in the ventrolateral fasciculi and ventral funiculus. The serotonergic (5HT) fibers described by DahlstrA¶m and Fuxe ('65) to terminate in the dorsal horn, intermediolateral cell column, and ventral horn are likely to coincide with the raphe-spinal projections documented in this work.

Pharmacogenetics of tolbutamide metabolism in humans

Abstract: This study was designed to focus on the genetic control of tolbutamide dispositon in humans and to provide insight into the potential for high accrued blood levels in individuals receiving fixed dosage regimens. Tolbutamide was administered intravenously to 42 nondiabetic subjects, eight of their relatives, and to five sets of twins. A ninefold variation in the rate of tolbutamide disappearance from plasms (Kd) was found. This variation was characterized by a trimodal frequency distribution, suggestive of monogenic inheritance and consistent with pedigree analysis, indicating autosomal transmission of rapid and slow inactivation of tolbutamide. A heritability value of 0.995 for Kd indicated little influence of environmental factors on variation of this rate. Interindividual differences in the binding of 35S-tolbutamide to serum proteins were also assessed. No correlation was found between tolbutamide serum protein binding affinity and Kd. Analysis of the metabolites of tolbutamide in urine samples provided evidence for the microsomal oxidation of the drug to hydroxytolbutamide as the primary site of genetic control. In conclusion, this study provides evidence for monogenic control of tolbutamide metabolism in man. The results suggest that fixed dosage regimens of this drug, as were prescribed in the controversial University Group Diabetes Program study, might lead to higher accrued blood levels in slow inactivators.

Development of an Instrument to Measure Children's Health Locus of Control

Abstract: Studies were conducted with children ages 7 to 12 years to develop an instrument to measure children's health locus of control. Findings provide evidence that the Children's Health Locus of Control scale has acceptable levels of reliability, internal consistency, and construct validity. Item analysis and factor analysis were performed to determine item effectiveness and existence of significant subscales. Implications of this research for health education of children are discussed. Links between the theoretical basis for the locus of control construct and a more comprehensive explanation of health behavior are outlined.

Relationship of aortic wall and baroreceptor properties during development in normotensive and spontaneously hypertensive rats.

Abstract: We studied the relationship between aortic baroreceptor function and aortic wall properties in normotensive (NTR) and spontaneously hypertensive (SHR) rats 10-20 weeks old. Baroreceptor discharge, static pressure-volume (P-V), and pressure-radius relationships were measured in excised aortic segments. Histological studies of wall thickness and receptor numbers also were made. Circumferential wall stress and strain were calculated, as was the incremental elastic modulus (EINC). EINC in NTR's at 100 mm Hg was similar to values reported for in vivo human, dog, and rat aortas. At 10 weeks, SHR's had significantly elevated blood pressure, but SHR and NTR aortas had similar relationships among pressures, volumes, strains, and EINC's. Differences arose subsequently and, at 20 weeks, NTR aortas had larger volumes, larger strains, and smaller EINC's at equivalent pressures, whereas SHR aortas were unchanged. Thus the reduced distensibility of SHR relative to NTR aortas, rather than being due to retrogressive changes from normal, appeared to result from a failure to pass through a phase of increased distensibility. At 10 weeks, SHR baroreceptors showed resetting in both pressure-response and strain-response curves, and it was concluded that early hypertensive baroreceptor resetting was due to primary changes in the receptors. At 20 weeks, the order of the strain-response curves for NTR and SHR baroreceptors was reversed due to a reduction in strain sensitivity of NTR baroreceptors. Resetting of NTR baroreceptors during development may have important implications as a mechanism of blood pressure control in development.

Depression of primate spinothalamic tract neurons by iontophoretic application of 5-hydroxytryptamine

Abstract: The effects of iontophoretic applications of 5-hydroxytryptamine (5-HT) were tested upon primate spinothalamic tract neurons recorded extracellularly in the spinal cord of anesthetized monkeys. The activity of most high threshold and wide dynamic range spinothalamic tract cells was depressed. 5-HT also reduced the responses of the cells to glutamate pulses which by themselves had a powerful excitatory action. It is concluded that 5-HT has a depressant action upon the postsynaptic membranes of spinothalamic tract cells, although the action has a slow time course. The observations are consistent with, but by no means prove, the hypothesis that serotonergic pathways descending from the brain stem produce a postsynaptic inhibition of spinothalamic tract neurons.

Motion of the rib cage and the abdomen in tetraplegic patients.

Abstract: 1. We have studied the motion of the abdomen and the rib cage in patients with a transection of the lower cervical spinal cord during normal breathing both in the supine and sitting posture, and compared it with that of normal subjects. 2. In the supine posture the rib cage of a patient moves paradoxically inward, therefore his chest wall is deformed, which explains the high work of breathing. 3. During expiration, beside the recoil of the respiratory system, there is also the recoil of the deformed chest wall, toward its passive configuration, with an expansion of the rib cage above its resting position during the first part of expiration and an alteration of the expiratory flow profile. 4. In a sitting 'relaxed' posture the paradoxical inward motion disappears in the lower rib cage, and it is reduced but still present in the higher rib cage. 5. We conclude that contraction of the diaphragm constricts the 'passive rib cage', either directly through its insertions or indirectly through the reduction of intrathoracic pressure. In seated subjects the diaphragm causes some expansion of the rib cage at its lower level. Therefore the motion of the rib cage is not only related to the balance between the forces developed by the diaphragm and the intercostal muscles, but also to the diaphragm dome configuration, the geometry of the rib cage and the lung volume.

Isolation of human nerve growth factor from placental tissue

Abstract: Nerve growth factor (NGF) has been isolated from human placental tissue. Using the chicken embryo dorsal root ganglia assay, we determined levels of NGF activity for the amnion, placental cotyledons, cord serum, fetal serum, and maternal serum. The highest levels of NGF activity were measured in placental cotyledons. After homogenization and centrifugation of the placental cotyledons, the supernatant was sequentially chromatographed, at neutral pH, on Sephadex G-100, DEAE-11, and Sephadex G-150. A high-molecular-weight protein fraction (≈150,000), which contained all the biological activity, was isolated in this fashion. Analytical isoelectric focusing of this fraction revealed a basic protein component (pI 9.5) of the high-molecular-weight species. Assays for NGF activity of all protein components separated by analytical isoelectric focusing showed that NGF activity was associated only with the basic protein component. Correspondingly, preparative isoelectric focusing of the high-molecular-weight species yielded a basic protein with very high biological activity (1–3 ng per biological unit) that was immunochemically active against rabbit IgG made against mouse β-NGF.

Basolateral membrane potential of a tight epithelium: ionic diffusion and electrogenic pumps.

Abstract: Summary. The contribution of specific ions to the conductance and potential of the basolateral membrane of the rabbit urinary bladder has been studied with both conventional and ion-specific microelectrode techniques. In addition, the possibility of an electrogenic active transport process located at the basolateral membrane was studied using the polyene antibiotic nystatin. The effect of ion-specific microclectrode impalement damage on intracellular ion activities was examined and a criterion set for acceptance or rejection of intracellular activity measurements. Using this criterion, we found (K+)=72m~ and (CI)=15.8mM. CI- but not K + was in electrochemical equilibrium across the basolateral membrane. The selective permeability of the basolateral membrane was measured using microelectrodes, and the data analyzed using the Goldman, Hodgkin-Katz equation. The sodium to potassium permeability ratio (PNa/PK) was 0.044, and the chloride to potassium permeability ratio (Pcl/PK) was 1.17. Since K § was not in electrochemical equilibrium, intracellular (K § is maintained by active metabolic processes, and the basolateral membrane potential is a diffusion potential with K + and C1- the most permeable ions. After depolarizing the basolateral membrane with high serosal potassium bathing solutions and eliminating the apical membrane as a rate limiting step for ion movement using the polyene antibiotic nystatin, we found that the addition of equal aliquots of NaC1 to both solutions caused the basolateral membrane potential to hyperpolarize by up to 20 mV (cell interior negative). This potential was reduced by 80 ~o within 3 min of the addition of ouabain to the serosal solution. This hyperpolarization most probably represents a ouabain sensitive active transport process sensitive to intracellular Na +. An equivalent electrical circuit for Na § transport across rabbit urinary bladder is derived, tested, and compared to previous results. This circuit is also used to predict the effects that microelectrode impalement damage will have on individuM membrane potentials as well as time-dependent phenomena; e.g., effect of amiloride on apical and basolateral membrane potentials.

Serotonin shifts the phase of the circadian rhythm from the Aplysia eye.

Abstract: A putative neurotransmitter, serotonin, may be used to transmit temporal information in the eye of Aplysia, because it can shift the phase of the circadian rhythm of spontaneous optic nerve impulses from the eye and the eye contains a significant quantity of serotonin. Serotonin acts either directly on the cell, or cells, containing the circadian pacemaker or on cells electronically coupled to the pacemaker cells.

Estrogenic activities of chlorinated hydrocarbons.

Abstract: Some DDT analogs are estrogenic, particularly o,p'-DDT, which comprises approximately 15-20% of the commercial DDT mixture. Whether this compound or its metabolites are active has not been established. In fact, the data obtained thus far are more confusing than enlightening. For example, CCl4 pretreatment of immature female rats has been reported to inhibit or enhance estrogenic activity of o,p'-DDT, and SKF-525A pretreatment has been reported to enhance or not alter the estrogenic effect. Although o,p'-DDT inhibits binding of estradiol to the estrogen receptor from rat or human at low levels (approximately 1-10 micrometer) in vitro, higher levels are required to inhibit nuclear binding of [3H] estradiol in incubated whole uteri. Futhermore, o,p'-DDT appears to be neither estrogenic nor antiestrogenic in an in vitro estrogen assay. Methoxychlor appears to be "activated" by metabolism, and it is probable that phenolic metabolites are responsible for its estrogenic activity. Since chlorinated hydrocarbons often enhance the metabolism of steroids and may reduce circulating levels of steroids, interactions of the exogenous hormonally active agents with steroid receptors may be self-potentiating in vivo.

Analysis of Adenosine and Other Adenine Compounds in Patients With Immunodeficiency Diseases

Abstract: Adenine compounds can be measured in picomole amounts using liquid chromatography of the fluorescent 1, N6-etheno derivatives. The limit of detection for the etheno derivatives in tissue extracts, however, is tissue-dependent due to interference by nucleotides and fluorescent components which are normally present. Prior to derivatization nucleotides were partially removed from extracts of lymphocytes and erythrocytes by treatment with Dowex AG1-X2 anion exchange resin. Samples were analyzed using either a Partisil PXS 10/25 SCX column eluted with 100 mM NH4H2PO4, pH 4.5, at a flow rate of 2 ml/min; or using two μBondapak/C18 reversed-phase columns eluted with 5 mM KH2PO,4:25% methanol (V/V) pH 7.5, at a flow rate of 1 ml/min. Adenosine was found to be 0.07 nmole/ml in normal adult human plasma. The urine of a child with severe combined immunodeficiency disease associated with absence of adenosine deaminase contained a normal amount of adenosine (5–6 nmole/ml), but contained a high level (∼60 nmol...

Academic and personal predictors of clinical success in medical school.

Abstract: Admissions interview data and college academic credentials of five classes of University of Missouri-Columbia medical students were evaluated as possible predictors of clinical success. Those students who were judged by admissions interviewers to have high levels of maturity, nonacademic achievement motivation or rapport were approximately two to three times as likely to receive outstanding internship recommendations as those without such personal characteristics. Under-graduate grade-point average had a smaller but nevertheless significant relationship with clinical success as measured by internship letters. These data suggest that additional emphasis during selection upon applicants' personal characteristics would have enhanced the clinical success of these students.

Therapy with hyperbaric oxygen for experimental osteomyelitis due to Staphylococcus aureus in rabbits.

Abstract: Hyperbaric oxygen (HBO) is used as adjunctive therapy of chronic osteomyelitis, but its efficacy remains controversial. A recently developed rabbit model for osteomyelitis due to Staphylococcus aureus was used to compare the results of treatment with HBO, cephalothin, a combination of both, or no treatment. Cultures of bone were positive in 10 (91%) of 11 control animals (untreated), five (36%) of 14 animals treated with HBO, eight (47%) of 17 treated with cephalothin, and six (40%) of 15 treated with HBO plus cephalothin. All three treatment groups differed significantly from untreated controls in the number of positive cultures obtained (P less than 0.01), but there were no significant differences among treatment groups. In vitro growth and killing curves (1.0 microgram of cephalothin/ml) constructed after exposure to HBO revealed no change from parallel control studies in ambient air. These data demonstrate that therapy with HBO is at least as effective as antibiotic therapy. The therapeutic effectiveness of HBO does not appear to be related to antibacterial activity.

Influence of cyclic AMP on intracellular pH regulation and chloride fluxes in barnacle muscle fibers.

Abstract: THE pH sensitivity of numerous intracellular processes requires the close regulation of internal pH (pHi). As the pHi of many cells is maintained at a higher value than it would have if H+ were at equilibrium across the cell membrane, it follows that the acidifying effects of cellular metabolism and of passive H+ influx and HCO−3 efflux must be balanced by active acid extrusion. It is now generally accepted that this extrusion is stimulated by decreases in pHi, and that, in several cells, it is accomplished by exchanging external HCO−3 for internal Cl− (refs 1–4). Recently, a role for cyclic 3′,5′-adenosine monophosphate (cyclic AMP) in pHi regulation was suggested by the observation that dibutyryl cyclic AMP attenuates the CO2-induced fall of pHi in mammalian cardiac muscle5. We now report experiments on the effects of cyclic AMP on acid extrusion and on accompanying Cl− fluxes in the barnacle muscle fibre, a preparation known to contain cyclic AMP (ref. 6). Our data show that internally applied cyclic AMP enhances the response of the pHi-regulating system to acid loads.

A documentation of an age related increase in neuronal and axonal numbers in the stingray, Dasyatis sabina, Leseuer

Abstract: The present study documents that in the stingray Dasyatis sabina the numbers of (1) dorsal root ganglion cells, (2) dorsal root axons, (3) ventral root axons and (4) “motor” cells in the ventral horn increase steadily as the animals increase in size. This increase in axonal and neuronal numbers persists much further into adult life than is the case for other vertebrates that have been studied from this point of view. We hypothesize this steady increase in axonal numbers may be related to the ability of fish to regenerate parts of their central and/or peripheral nervous systems.

Inactivation without facilitation of calcium conductance in caesium-loaded neurones of Aplysia.

Abstract: THE concentration of cytoplasmic free calcium (Ca) ion regulates a variety of cellular processes1–4, including hormone secretion, histamine secretion, neurotransmitter release, mitosis and muscle contraction. For some of these processes the activating signal is a rapid influx of Ca ions across the plasma membrane during an action potential. One way of controlling the magnitude of such processes would be a regulation of the amount of Ca influx during each action potential. A mechanism capable of this type of control has recently been ascribed to the Ca conductance system of molluscan neurones. It is called ‘Ca facilitation’, and is an increase in the inward Ca current (ICa) observed when a test voltage-clamp pulse is preceded by a depolarised, conditioning prepulse5–8. Ca facilitation could cause an enhanced Ca influx during a repetitive train of action potentials. An opposing process, Ca inactivation, has also been described in excitable tissue9–13. Ca inactivation, like Na inactivation, is a decrease in inward current caused by a depolarising prepulse. Thus, facilitation would cause an increase and inactivation a decrease in ICa during repetitive voltage-clamp pulses. Facilitation of ICa has not been observed directly under voltage-clamp because inward ICa is usually accompanied by a large, outward K current (IK) (ref. 14). We have eliminated IK by using a new technique to replace intracellular potassium with caesium, and report here that ICa inactivates without evidence of facilitation.

Dopaminergic inhibition of adrenergic neurotransmission as a model for studies on dopamine receptor mechanisms.

Abstract: Dopamine and apomorphine produced concentration-dependent inhibition of adrenergic neurotransmission in the isolated, perfused, rabbit ear artery The inhibitory action of both dopamine and apomorphine was competitively antagonized by haloperidol and several other antipsychotic drugs The calculated affinities of these drugs for the dopaminergic receptor correlate closely with both the pharmacological potencies of these drugs in vivo and their reported potencies as inhibitors of [3H]haloperidol binding to "dopamine receptors" in brain homogenates

Sodium Channel Inactivation in Squid Axon is Removed by High Internal pH or Tyrosine-Specific Reagents

Abstract: In squid axon, internal alkalinization from pH 7.1 to pH 10.2 results in a reversible decrease of the maximum inward current and the steady state sodium channel inactivation. Similar effects were observed after treatment of the axon with tetranitromethane or after iodination with lactoperoxidase. These results suggest that a tyrosine residue is an essential component of the inactivation process in this nerve.

Structure and functional development of the eel leptocephalus Ariosoma balearicum (De La Roche, 1809)

Abstract: Eels, elopids, notacanths and other elopomorph fishes spawn in the ocean and the hatchlings spend their larval life as pelagic, planktonic organisms. The larvae are known as leptocephali and their transparent, leaf-like body characteristically bears little resemblance to the respective adult form. Planktonic life in the ocean may last for years before the leptocephalus undergoes a morphological transformation and takes on a recognizable fish-like appearance. A prolonged larval life suggests a delay in structural and functional development and this premise was the basis for the present study. Before this work on morphology, chemical analysis of the whole leptocephalous body indicated an internal salinity and osmolality far and above the known values for marine teleost fishes. For that reason, particular attention was given to the structural maturation of the gills, gut and kidney, all of which are intimately concerned with osmoregulation. The leptocephalus of the bandtooth conger Ariosoma balearicum was chosen for morphological studies because of its abundance in the tropical western Atlantic and because the Bathymyrinae, which includes , is a reasonably generalized subfamily of congrid eels. The congrids are primitive and representative of the basic eel plan and, as such, are accorded a rather ancestral position. In order to grasp the fundamental organization of a leptocephalus it was soon discovered that all parts of the body needed to be examined. One by one, a long list of structural peculiarities came to light, each of which seemed to have a direct relation to the functional adaptation of the leptocephalus for a prolonged oceanic existence. The section describing the chondrocranium is particularly detailed and permits comparison with an examination of the leptocephalous skull in Anguilla performed by Norman some fifty years ago. The advantages of current methods for processing tissue and the electron microscope are evident in the micrographs of cell surfaces and intracellular organelles. Gill function in the premetamorphic leptocephalus is limited by structure to a mandibular hemibranch. The four gill arches are present, but the vasculature is undeveloped and gill filaments are absent. The gastrointestinal tract is always devoid of food material and some sections of the intestine do not have a discernible lumen. The size, shape and appearance of the teeth seem unrelated to the source of nutrition. All kidney tubules are aglomerular. In summary, the leptocephalus demonstrates many features of structural and functional immaturity and, until transformed by metamorphosis, appears to be an obligatory inhabitant of the open ocean.

Measuring relative electrophoretic mobilities of mutant hemoglobins and globin chains.

Abstract: A system of calculating relative mobilities of mutant hemoglobins and globin chains in four methods of zone electrophoresis is described. In electrophoresis on cellulose acetate, TEB buffer, pH 8.5, mobilities are calculated as ratios of the mobility of simultaneously analyzed Hb C. In electrophoresis on citrate agar, pH 6.0, anodic mobilities are also related to Hb C, cathodic ones to Hb F. In globin electrophoresis in urea 2-mercaptoethanol buffers, pH 6.0 and 8.9, mobilities of the mutant globin chains are calculated in relation to the mobilities of normal alpha and beta chains. These calculations provide objective comparisons of mobilities of hemoglobins, including those analyzed at different times. The combined data permit recognition of many mutant hemoglobins.