Biomedical subjects

L Kass

Publications and source records attributed to L Kass.

At least 37 records · Page 2Linked to original sources

PubMed1996

Retinal anatomy of a new species of bresiliid shrimp from a hydrothermal vent field on the Mid-Atlantic Ridge.

A new species of shrimp (Rimicaris sp.) was recently collected from the Snake Pit hydrothermal vent field on the Mid-Atlantic Ridge. Until the discovery in 1989 that the deep-sea, hydrothermal vent species, Rimicaris exoculata, possessed a hypertrophied dorsal eye, everyone believed that animals recovered from vent environments were blind. Like R. exoculata, Rimicaris sp., a small orange bresiliid shrimp, has an enlarged dorsal eye specialized for detecting light in a very dim environment instead of the expected compound eye. The individual lenses characteristic of a compound eye adapted for imaging have been replaced in Rimicaris sp. by a smooth cornea underlain by a massive array of photosensitive membrane. The number of ommatidia in this species is about the same as in shrimp species that live at the surface; however, the photoreceptors are larger in the deep-sea species and the shape of the photoreceptors is markedly different. The light-sensitive region of the photoreceptor is much larger than those of other shrimp and the rest of the receptor is much smaller than normal. All screening pigment has moved out of the path of incident light to a position below the retina, and the reflecting pigment cells have adapted to form a bright white diffusing screen between and behind the photoreceptors. The ultrastructure of the microvillar array comprising the rhabdom is typical for decapod crustaceans; however, there is a much greater volume density of rhabdom (80% to 85%) than normal. There is no ultrastructural evidence for cyclic rhabdom shedding or renewal. Rimicaris sp. has apparently adapted its visual system to detect the very dim light emitted from the throats of the black smoker chimneys around which it lives.

Animals↗

PubMed1995

A hypochlorite-fast metachromatic quick stain for human megakaryocytes.

Megakaryocytes in aspirates of normal and abnormal human bone marrow displayed rose-pink metachromasia when stained with a violet polymethine dye. The color of the megakaryocytes persisted when the stained sample was exposed to a dilute solution of sodium hypochlorite. Under the same conditions, other hematopoietic cells became colorless. This stain may be useful for demonstrating megakaryocyte from both healthy and diseased bone marrow specimens.

Bone Marrow Cells↗

PubMed1995

Identification of normal and abnormal human megakaryocytes based on acid fast metachromasia after staining with basic black MSP.

Megakaryocytes from normal persons and from patients with immune thrombocytopenic purpura, myelodysplastic disorders, hypersplenism, and essential thrombocythemia displayed vivid magenta metachromatic staining of the cytoplasm when stained with basic black MSP followed by brief exposure to dilute hydrochloric acid. Under the same conditions, other hematopoietic cells were completely decolorized. Acid fast metachromasia of megakaryocytes facilitates their identification, particularly in cases of small and atypical megakaryocytes found in disease states.

Bone Marrow Cells↗

PubMed1995

A selective stain for eosinophils using two oxazine dyes applied sequentially.

A methanolic solution of the oxazine textile dye, C.I. basic blue 122, followed by an aqueous alkaline solution of the oxazine dye, C.I. basic blue 141, and a brief rinse in an acetate buffer at pH 3.45 produces intense black staining of eosinophil granules. This staining was selective for eosinophils while other types of peripheral blood leukocytes showed little if any staining under the same conditions. This staining procedure may be useful for detecting eosinophils in samples of blood, bone marrow, or urine when eosinophiluria results from interstitial nephritis.

Eosinophils↗

PubMed1995

Identification of proerythroblasts in tissue sections of bone marrow.

In paraffin-embedded sections of bone marrow fixed in B5-formalin, proerythroblasts from patients with marked erythroid hyperplasia displayed a characteristic nuclear chromatin pattern. This pattern consisted of an "arm" of chromatin extending from the center of the nucleus to the inner aspect of the nuclear envelope. In some instances the arm showed an "elbow bend." Depending on the plane of section, approximately 30% of proerythroblasts demonstrated these chromatin patterns. Ultrastructurally a similar "arm" of chromatin was seen in proerythroblasts. Embedded within the chromatin was a nucleolus. Although the significance of this pattern is as yet unknown, it provides a morphologic clue to identification of proerythroblasts in tissue sections.

Bone Marrow↗

PubMed1993

Rapid identification of T helper and T cytotoxic/suppressor lymphocytes with an oxazine dye.

Peripheral blood lymphocytes displayed a plurality of sizes and colors when exposed first to a methanolic solution of C.I. basic blue 141, then to an aqueous alkaline solution of the same dye and rinsed in a neutral HEPES buffer containing trace amounts of various salts. As confirmed with purified lymphocyte subpopulations obtained with a cell sorter, T helper cells (CD4) were small and their nuclei and cytoplasm stained deep blue. T cytotoxic/suppressor cells (CD 8) were larger than T helper cells, their nuclei stained pale green or blue green and their cytoplasm contained a cluster of magenta colored granules. From start to finish, the stain takes 15 min to perform. Used in the manner described, basic blue 141 holds promise as a rapid means of identifying and differentiating CD4 and CD8 cells under the ordinary light microscope without using monoclonal antibodies or fluorescence.

Humans↗

PubMed1992

A circadian clock in the Limulus brain transmits synchronous efferent signals to all eyes.

A circadian clock in the brain of the horseshoe crab, Limulus polyphemus, has an important role in the function of the peripheral visual system. At night, the clock transmits neural activity to the lateral, ventral, and median eyes via efferent optic nerve fibers. The activity occurs in synchronous bursts (maximum rate of 2 bursts/s) with individual efferent fibers contributing a single spike in each burst. The circadian efferent activity originates in the protocerebrum. Lateral connections synchronize the efferent activity recorded from the two halves of the protocerebrum, suggesting the existence of bilateral circadian oscillators. Circadian efferent activity survives excision of the brain and isolation of the protocerebrum. We conclude that circadian clock and its complex neural circuitry are fundamental components of the Limulus visual system.

Animals↗

PubMed1992

Basic blue 54: a new colorant for monocytes.

C.I. basic blue 54, a sulfur containing azo textile dye, stained the nucleus and cytoplasm of normal and leukemic monocytes bright red-violet. Essential for the staining reaction was a brief final rinse in a pH 3.6 acetic acid-sodium acetate buffer. Coloration of the type found in monocytes was not observed in other types of mature and immature leukocytes.

Azo Compounds↗

PubMed1992

A two step stain for normal and leukemic monocytes using two different dyes applied in sequence.

A staining procedure for monocytes in specimens of blood and bone marrow was developed. The technique was a two step procedure in which unfixed cells were exposed first to a methanolic solution of C.I. basic blue 54. Next, an aqueous alkaline buffered solution of C.I. basic blue 141 was added to the first staining solution. After staining for 10 min in the solution with two stains, slides or coverslips were washed for 5 sec in pH 5.6 phosphate buffer and drained dry. The cytoplasm of monocytes stained intensely deep purple and frequently nuclei were stained red. Similar staining was not found in other types of normal or abnormal blood and bone marrow cells.

Buffers↗

PubMed1991

Visual performance of horseshoe crabs day and night.

A circadian clock modulates the structure and function of the lateral eyes of Limulus polyphemus, greatly increasing their sensitivity at night. During the mating season, male Limulus are visually attracted both day and night to females and objects that resemble females. This paper asks how well Limulus can see day and night, and whether the circadian changes in retinal sensitivity might influence the ability of these animals to find mates. We recorded the visual behavior of male and female horseshoe crabs in the vicinity of an object--a cement hemisphere (29.5 cm diameter) similar in size and shape to a female horseshoe crab--placed in a mating area near Mashnee Dike, Bourne, Massachusetts. Males oriented toward this target from an average distance of 0.94 m during the day and 0.88 m at night; and females appeared to avoid the target. We conclude that males can see potential mates at night almost as well as they can during the day. Apparently the circadian changes in the retina help compensate for the daily changes in illumination in the animal's normal environment. This study provides the first evidence for a role of visual circadian rhythms in an animal's natural behavior.

Animals↗

PubMed1991

Basic blue 75: a new stain for erythroblasts.

C.I. basic blue 75 in an aqueous alkaline solution stains the nuclei of mature and immature erythroblasts bright red. Simultaneously, the stain colors the cytoplasm of erythroblasts blue in immature cells and purple in mature cells. Colors of the type described were not found in other normal and abnormal hematopoietic cells.

Bone Marrow↗

PubMed1990

New stains for blood and bone marrow cells.

Traditionally, blood and bone marrow cells have been identified based on their characteristic shapes and colors when stained with one of several panoptic stains including Wright's or Giemsa's. As questions arose regarding the origin of normal and leukemic cells, cytochemical stains were developed. These stains help identify cells on the basis of a distinctive metabolite or enzyme. As part of an ongoing tradition in which textile dyes are used for biological staining, several new stains have been applied to hematologic staining. These include C.I. basic blue 41, basic blue 141, basic blue 93, and an asymmetrical polymethine dye. As additional cell-selective stains are developed, we can anticipate further improvements in our ability to identify normal and malignant hematopoietic cells.

Blood Cells↗

PubMed1988

Efferent neurotransmission of circadian rhythms in Limulus lateral eye. II. Intracellular recordings in vitro.

We investigated efferent neurotransmission in the Limulus lateral eye by studying the action of pharmacological agents on responses of photoreceptor cells in vitro. We recorded transmembrane potentials from single cells in slices of retina that were excised during the day and maintained for several days in a culture medium. Potentials recorded in the absence of pharmacological agents resemble those recorded from cells in vivo during the day. Octopamine, a putative efferent neurotransmitter, induced changes in photoreceptor potentials that mimicked in part those generated at night by a circadian clock located in the brain. Specifically, octopamine (100 to 500 microM) decreased the frequency of occurrence of quantum bumps in the dark and increased the amplitude of photoreceptor responses to intermediate and high light intensities. Similar actions were produced by naphazoline (25 to 100 microM, potent agonist of octopamine), forskolin (8 to 400 microM, activator of adenylate cyclase), IBMX (1 mM, inhibitor of phosphodiesterase), and 8-bromo-cAMP (500 microM, analogue of cAMP). 8-bromo-cGMP (500 microM, analogue of cGMP) decreased the rate of spontaneous quantum bumps only. Our results support the hypothesis that (1) octopamine is an efferent neurotransmitter of circadian rhythms in the Limulus eye and that (2) it activates adenylate cyclase to increase levels of the second messenger, cAMP, in photoreceptor cells. Circadian changes in photoreceptor responses to moderate intensities may be a specific action of cAMP, since cGMP has no effect. Circadian changes in the rate of spontaneous quantum bumps may involve a less specific intermediate, since both cAMP and cGMP reduce bump rate. Characteristics of the retinal slice preparation precluded a detailed study of the effects of pharmacological agents on retinal morphology.

1-Methyl-3-isobutylxanthine↗

PubMed1988

Circadian rhythms in adaptation to light of Limulus photoreception.

1. The lateral eye of Limulus responds differently to light-adaptation depending upon whether the eye is tested during the day, or at night when a central circadian clock is known to activate efferent fibers that terminate in the retina. 2. At night, the decrement in retinal sensitivity due to light-adaptation is less pronounced immediately following a light-flash but is greater at longer times after the flash when compared with responses recorded during the day. 3. In our quantitative description of dark adaptation we find that at least two time constants are needed to describe the time course, and that the two decaying exponentials are differentially altered by circadian clock action. 4. We relate these day-to-night alterations in light-adaptive properties to circadian changes in physiology and morphology studied previously in Limulus photoreceptors.

Adaptation, Physiological↗

PubMed1988

Circadian change in function of Limulus ventral photoreceptors.

Efferent fibers from a central circadian clock innervate photoreceptors along the ventral nerve of Limulus and release octopamine when active. We have recorded ERG-like responses from the ventral eye in vivo over several day periods. We have also used intracellular microelectrodes to study changes in ventral photoreceptor function during exogenous applications of octopamine (the putative efferent neurotransmitter), IBMX (a phosphodiesterase inhibitor), and forskolin (an adenylate cyclase activator): (1) Responses to light measured at night from ventral photoreceptors in vivo are greater in amplitude than those recorded during the day; (2) Octopamine and agents that increase intracellular levels of cAMP in ventral photoreceptors decrease the rate of spontaneous (dark) bumps, increase photoreceptor response to light without changing threshold, and often increase the bump duration; and (3) These changes in function of ventral photoreceptors are similar to those that have been observed in the photoreceptor of the lateral eye during circadian clock activity at night, and in vitro in the presence of those same pharmacological agents.

1-Methyl-3-isobutylxanthine↗

PubMed1988

Basic blue 93. An alternative to the traditional myeloperoxidase stain.

This report describes the selective staining of lysosomes in cells of neutrophilic granulocytic origin by the azo textile dye basic blue 93. Used as a single agent aqueous stain after fixation, the dye stained lysosomes black. Stained in this way, lysosomes were sharply delimited and easily visualized. Large numbers of black-stained lysosomes occurred in immature granulocytes like promyelocytes and myelocytes. In more mature granulocytes like metamyelocytes, bands, and neutrophils, substantially fewer numbers of lysosomes were detected. In leukemic myeloblasts and promyelocytes stained with basic blue 93, variable numbers of black-colored lysosomes could be detected and usually paralleled the reactions for myeloperoxidase and Sudan black B in the same cells. As an alternative to the traditional stains for myeloperoxidase, basic blue 93 has several advantages, including simplicity of use, ability to stain aged specimens, and stability of the reaction product.

Azo Compounds↗

PubMed1988

Identification and function of octopamine and tyramine conjugates in the Limulus visual system.

Major metabolites of octopamine and tyramine in the Limulus nervous system are identified here as gamma-glutamyl octopamine and gamma-glutamyl tyramine. We show that these conjugates are normal products of amine metabolism in Limulus, and that they are normally present in octopamine-rich Limulus tissues. The synthesis of these conjugates is not restricted to nervous tissue, but the highest activity of gamma-glutamyl amine synthetase was measured in the CNS. Our interest in these molecules stems from our previous observations which showed that they were synthesized and stored in, and released from, the efferent fibers to Limulus eyes which modulate the sensitivity of the eyes to light. Here we provide direct evidence for the release of the conjugates from Limulus eyes in response to depolarization, and that gamma-glutamyl octopamine can increase the sensitivity of the lateral eye to light. Our observations lend support to the hypothesis that gamma-glutamyl octopamine may serve as an intercellular messenger in the Limulus visual system.

Animals↗

PubMed1988

Identification of lymphocyte subpopulations with a polymethine dye.

Using the polymethine dye p-ethoxyphenyl-p-aminostyryl-1,3,3-trimethyl-3H-indolium chloride as an aqueous stain applied to specimens of peripheral blood or buffy coat fixed in FAA fixative, differential coloration of leukocytes was achieved using darkfield illumination. Neutrophils stained dark maroon and contained green granules, eosinophils contained bright blue granules, basophils revealed yellow and pink granules, and monocytes stained green with green and yellow vacuoles. In studies of purified lymphocyte subpopulations obtained in a cell sorter, T-helper cells stained red, T-suppressor cells were yellow orange, B-cells appeared yellow and often contained yellow annular structures in the cytoplasm, and natural killer (NK) cells stained green and contained large green granules. As a rapid screening technique for identification of T-helper and T-suppressor cells and their ratios in health and disease, the new polymethine stain may complement the more complex monoclonal antibody techniques for identification of these cells.

Coloring Agents↗