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A Rosado

Publications and source records attributed to A Rosado.

144 records · Page 8Linked to original sources
PubMedDate not supplied

Participation of DNA structure on sperm chromatin organization.

The in vitro interaction between purified bovine liver and sperm DNA with somatic histones, to form nucleosomes, and with bovine and salmon protamines were studied. DNAse or microccocal nuclease digestion of liver DNA-histone reassociated chromatin produced the expected polynucleosome type of fragments. Electrophoretic patterns of digested sperm-DNA nucleosomes were different. Micrococcal nuclease digestion produced mainly fragments smaller than 100 bp and some nucleosome-type particles. Under DNAse activity most of the products were smaller than 100 bp, indicating an increased susceptibility of the sperm DNA-histone complexes to the hydrolytic activity of both nucleases, particularly toward DNAse I. This differential susceptibility was confirmed by sucrose gradient spectrophotometric analysis. Acridine orange (AO) staining of histone-DNA reassociated nucleosomes showed significant differences in fluorescence intensity, sperm DNA-histone complexes being almost twice as fluorescent as liver DNA-histone complexes. On the contrary, liver DNA/protamine complexes stained with AO were consistently more fluorescent than sperm DNA-protamine complexes. Finally, no differences in either fluorescence intensity or spectra were observed when liver and sperm DNA were stained with AO after interaction with salmon protamines. The data suggest that sperm DNA has important structural characteristics that differentiates it from somatic DNA. These differences seem to be species specific and must surely play an important role on the determination of the dramatic sequence of that participates sperm chromatin organization.

Animals↗
PubMedDate not supplied

Sperm chromatin.

Available data on dry and hydrated nuclear volume of mammalian spermatozoa indicate that available volume is clearly insufficient to contain sperm chromatin packed in nucleosome-like structures. Therefore, sperm DNA-protein complexes must be packed differently than somatic DNA-protein complexes. Packing of DNA in fixed, dehydrated mammalian sperm approaches the physical limits of molecular compaction, making mammalian sperm chromatin the most condensed eukaryotic DNA known. The fundamental packaging unit of sperm chromatin is a toroid approximately 900-A outer diameter. 200-A thickness, and 150-A diameter hole. Each toroid contains 60 kilobases of DNA and is linked to other toroids by uncoiled DNA stretches. The factors that contribute to mammalian chromatin structuration are still under study. The role of protamines in sperm chromatin condensation and nuclear shaping has been overstressed to the exclusion of other possible factors. Chromatin organization in sperm nuclei is maintained during sperm condensation by tight interactions with the nuclear matrix at fixed sites, inducing the formation of individual toroid-shaped DNA loop stuctures. Observations that abnormal manchettes affect sperm head shape and chromatin organization inducing sterility speak about manchette importance during chromatin organization. The presence in sperm chromatin of regions packaged in specific ways with several types of protamines or even with histones, indicates that nuclear shaping and chromatin organization must be under DNA control. The structural properties that distinguish sperm DNA from somatic DNA may play the most important role in chromatin organization.

Animals↗
PubMedDate not supplied

Changes in the quality of rabbit semen in 14 consecutive ejaculates obtained every 15 minutes.

Modifications of semen quality related to ejaculation frequency is one of the most important and neglected factors from the standpoint of artificial insemination or sperm competition. New Zealand white rabbits (Oryctolagus cuniculus) offer an advantageous experimental model because they have characteristic sexual behavior, they present rapid ejaculation after a single intromission, they have a very short interval between successive ejaculations, and semen can be easily collected. The authors studied the modifications on sperm quality (semen volume, sperm concentration, sperm motility) produced by 14 consecutive ejaculations recovered every 15 min using stimulus females and an artificial vagina. Bucks were exposed every 15 min to a sexually receptive female. After each ejaculation the female was removed and reintroduced 15 min later. Sperm concentration showed a clear biphasic conduct. The amount of spermatozoa per milliliter decreased rapidly until ejaculate number 6, showed a highly significant increase in ejaculates 7-9, and decreased to nil in the last 2 ejaculates. Total number of ejaculated spermatozoa was 557 x 10(6), 76% of which were recovered from the first 4 ejaculates. Ejaculate volume also showed a biphasic conduct. In the first ejaculates the volume decreased linearly until ejaculate number 6, showed a significant increase in ejaculates 7-10, and then decreased. The total semen volume recovered during the experiment was 2.44 mL, 40% of which (0.98 mL) was recovered from the first 2 ejaculates. Individual motility in the first 6 ejaculates was preferentially progressive (60% of the sperms) and turned to random or in situ from the seventh ejaculate up. The proportion of spermatozoa with cytoplasmic droplets increased from ejaculates 6 and 7 up. The results seem to reflect an acceleration of semen transport through the epididymis when the demands for spermatozoa increase.

Animals↗
PubMedDate not supplied

Therapeutic ultrasound in the treatment of retinal detachment: clinical observations and light and electron microscopy.

Osmotically-induced retinal detachments were created in rabbit eyes and treated with therapeutic ultrasound. Control eyes showed spontaneous retinal reattachment after ten days (range, 8-10 days), while eyes treated with therapeutic ultrasound showed retinal reattachment in a shorter time (average, 4.5 days). Light and electron microscopy demonstrates at least three major differences in the ultrasound-treated eyes compared to the controls. These findings are evidence of an earlier retinal reattachment, a stronger chorioretinal adhesion, less damage and faster repair in the ultrasound-treated retina than in the control retina. This method of producing chorioretinal adhesions may have applications in certain types of retinal detachments where choroidal thickness or vitreous opacity preclude conventional cryopexy, diathermy or photocoagulation techniques.

Animals↗
PubMedDate not supplied

Subcellular distribution of phospholipase A2 and ATPases during capacitation and acrosome reaction in guinea pig spermatozoa.

The presence, distribution, and levels of phospholipase A2 and ATPases activities in those structures of the guinea pig spermatozoa that participate in the acrosome reaction were studied, both before and after capacitation, as well as during the acrosome reaction induced in vitro. Spermatozoa were collected from the cauda epididymis and incubated in the absence and presence of 1.15 mmol/L calcium, with and without the addition of 1 mumol/L A23187. Membrane fractions were recovered by vortexing and discontinuous sucrose density gradient centrifugation. Most of the Na+, K(+)-ATPase was recovered in the acrosome-free spermatozoa, but a clear, distinct presence of this enzyme was observed in the plasma membrane (25 against 101 nmoles Pi released per milligram of protein, respectively). The activity of this enzyme in the periacrosomal plasma and in the outer acrosomal membrane increased during calcium incubation. Ca2(+)-dependent ATPase was found in both membrane fractions, being higher in the periacrosomal plasma membrane. The addition of calcium induced a significant inhibition of this acrosomal ATPase, whereas the activity in the acrosome-free spermatozoa increased. The activity of phospholipase A2, under all experimental conditions, was found to be restricted to the soluble fraction.

Acrosome↗
PubMedDate not supplied

Differential decondensation of class I (rat) and class II (mouse) spermatozoa nuclei by physiological concentrations of heparin and glutathione.

The kinetics of sperm nuclear decondensation induced by the action of physiological concentrations of heparin and glutathione was studied by comparing two rodents: the rat, with very stable protamine P1 containing chromatin (class I nuclei), and the mouse, with protamine P1 and protamine P2 (class II nuclei). Sperm suspensions were incubated at different temperatures (37, 40, 43, and 46 degrees C) in media while keeping a constant concentration of either heparin or GSH and increasing concentrations of the other reagent. Spermatozoa nuclei without any treatment incubated for 72 h appear densely condensed. Swelling of mouse spermatozoa nuclei was observed after 30 min of incubation in the presence of efficient concentrations of heparin-GSH. The extent of this time lag was significantly reduced at higher temperatures. This behavior was also observable in the rat, but required time lags of 3-4 h. Electron microscopy observations showed that the pattern of nuclear decondensation was different in both animal species. Mice sperm nuclei initiates its decompaction by the peripheral regions and this behavior remains until late stages of decondensation. On the contrary, rat spermatozoa nuclei decondense initially at the central part of the nuclei while the periphery remains condensed, showing numerous residues of densely packed chromatin. In both cases, the chromatin is organized into "hub-like" nuclear bodies joined by a network of chromatin fibers.

Animals↗
PubMedDate not supplied

Effect of heparin-reduced glutathione on hamster sperm DNA unpacking and nuclear swelling.

This study examined the kinetics of sperm nuclear decondensation induced by the action of physiological concentrations of heparin and glutathione in hamster sperm nuclei as a chromatin model that contains protamine P1 and P2. Sperm suspension was incubated at different temperatures (37, 40, 43, and 46 degrees C) in media, keeping constant the concentration of either heparin or GSH and increasing concentrations of the other reagent. Spermatozoa nuclei without any treatment, incubated for 72 h, appear densely condensed. Swelling of hamster spermatozoa nuclei was observed after 30 min of incubation in the presence of efficient concentrations of heparin-GSH. The extent of this time lag was significantly reduced at higher temperatures. DNA presence was verified by the use of ethidium bromide, acridine orange, and Feulgen stain. Phase-contrast microscopy shows that nuclear decondensation begins at the equatorial levels, with DNA highly condensed at the acrosome pole, and the basal pole as the DNA attachment point. Electron microscopy observations showed that hamster sperm nuclei initiates its decompaction at the peripheral regions and this behavior remains until late stages of decondensation, nevertheless, the chromatin is organized into "hub-like" nuclear bodies that measured 10-100 nm in diameter, joined by a network of chromatin fibers with apparent reduction in number. At the decondensation full stage, the network seems to be wide open with a reduced number of hub-like nuclear bodies present in the interlace. DNA is not organized into topologically constrained loop domains and is attached to the basal plate instead of to the nuclear matrix or any other structure.

Animals↗
PubMedDate not supplied

DNA unpacking in guinea pig sperm chromatin by heparin and reduced glutathione.

The kinetics of nuclear decondensation and DNA unpacking induced by the action of a physiological concentration of heparin and glutathione of guinea pig spermatozoa was studied. Sperm (acrosomeless) suspensions were incubated at several different temperatures (37, 40, 43, and 46 degrees C), with a constant concentration of either heparin (50 microM) or reduced glutathione (12.5 mM) and increasing concentrations of the other reagent. Nuclei spermatozoa remained highly condensed when incubated in the medium alone or in either GSH or heparin alone for up to 72 h. Swelling of nuclei spermatozoa was initially observed during the first 20 min of incubation. The sperm nuclei initiate decompaction at the central part of the nuclear structure while at the periphery there remain numerous residues of densely packed chromatin. The swollen chromatin pattern presents the characteristic organization into "hub-like" nuclear bodies that measured 10-100 nm diameter joined by a network of chromatin fibers. At full nuclei decondensation chromatin end fibers are loose, probably meaning that DNA is not organized into loop domains. DNA presence was verified by the use of ethidium bromide and acridine orange.

Animals↗
PubMedDate not supplied

[Analysis of fatty acids from strains of Mycobacterium habana and Mycobacterium simiae].

A comparative analysis of mycobacterial fatty acid fractions of Mycobacteriun habana and Mycobacterium sineae strains was made. This study used the gas-liquid chromatography coupled with mass spectrometry. Chromatographic profiles obtained from this technique were exposed and compared. This technique proves to be valuable as an alternative element in mycobacterial characterization and makes it possible to analyze the possible differences that may exist among mycobacterial species and to identify the present fatty acid fractions. The outcome proved that the studied strains had quantifiable quantities of over 20 C atom chain fatty acids. There are small differences among the strains in terms of these organic components. It was confirmed that each of then describes a characteristic chromatographic pattern although the composition of present fatty acids is very similar in both studied species.

Fatty Acids↗
PubMedDate not supplied

[Follicular maturation in the swine. Changes in the protein secretion pattern during follicular growth].

The formation of fluid, maturation and follicular differentiation are physiological processes unknown to this date. Therefore, changes in the electrophoretic pattern of proteins and glycoproteins in different states of maturation were studied, as well as the volume and protein concentration. Follicular fluid was collected from 43 follicles with a diameter of 2 mm., 45 follicles with a diameter of 5 mm. and 49 of 9 mm. The average of the concentration of protein for the 2 mm. follicles was 106 +/- 56.3 mg/ml of follicular fluid, for the 5 mm. ones 68.3 +/- 37.1 mg/ml and the 9 mm. ones had 52.9 +/- 21.3 mg/ml. In the protein and glycoproteins characterized by electrophoresis, a consistent pattern of 3 bands was found, and none were PAS positive in the 2 mm. follicles. In the 5 mm. follicles a 10 band pattern was found, of which 1 was PAS positive. In the last plane, the 9 mm. pattern was 12 and 2 respectively. The average value of follicular fluid was 5.3 +/- 1.8 microliters, for the 5 and 9 mm. it was 57 mu 25 microliters and 190 +/- 77 microliters respectively. Statistical analysis between volume and size show a highly significant correlation, thus suggesting the use of one of them to extrapolate the other.

Animals↗
PubMedDate not supplied

[Characterization of SH groups in the membrane proteins of human spermatozoa].

Membrane proteins rich in SH- groups were identified in human ejaculated spermatozoon, using the alkylation reaction with radioactive iodoacetic acid with a subsequent determination of the electrophoretic characterization of the proteins, as well as their comparison with the proteins in seminal plasma and blood serum of the same individuals. The determination of the incorporated radioactivity shows that out of 20 proteic bands identified by staining with Coomassie Blue, only 9 were alkylated with the iodoacetate. Among these 9 proteic bands, 4 are glycoproteins since they give a PAS positive reaction. All the proteins which incorporated the marked iodoacetate had a molecular weight below 67,000 daltons with a predominance of molecular weight below 25,000 daltons. A comparison of the electrophoresis obtained from the spermatozoon's plasmatic membrane, seminal plasma and blood serum, one finds that among the 9 proteins which were alkylated with the iodoacetate in the plasmatic membranes, two, bands I and IV are also found in the seminal plasma and blood serum, two more, bands VII and IX are found in the membranes and seminal plasma, but not in blood serum, while the rest are only found in the spermatozoon.

Blood Proteins↗
PubMedDate not supplied

[Male pseudohermaphroditism caused by enzymatic deficiency of 17-alpha-hydroxylase. 1st case reported in Puerto Rico].

A 36 year old white female came to our service after having been evaluated on repetitive occasions in the past for a workup of gigantism and acromegalic features. Since childhood she had developed tall stature, frontal bossing, prominence of zygomatic bones, separated teeth, large hands and size 14 shoes. Human growth hormone and somatomedin serum levels had been normal on all occasions tested. Her past history was significant for primary amenorrhea and a 12 year history of hypertension. On physical examination BP was 140/100, height 6' 2", weight 2571 bs. Her phenotype was truly acromegalic. There was absence of axillary and pubic hair with no breast development. External genitalia was of female appearance. Laboratory evaluation showed increased FSH of 88 mlU/ml, increase LH of 65.6 mlU/ml and decreased E2 of 12.6 pg/ml. Other findings were low serum cortisol of 0.2 mg/dl, high ACTH of 344 pg/ml, low 17-Ketosteroids, high pregnenolone levels of 595 mg/dl, low 17-hydroxypregnenolone less than 10 ng/dl, very high aldosterone of 31 ng/dl and suppressed PRA of less than 0.1 ng/ml. A pelvic sonogram showed a right ovoid structure which could represent a gonad and failed to identify the uterus and left gonad. A bone densitometry showed a decrease bone mineral density compatible with osteoporosis. Chromosome study showed a karyotype of 46-XY. A diagnosis was made of congenital adrenal hyperplasia secondary to 17-alpha-hydroxylase deficiency in a genotypic male. Our patient was referred to the department of gynecology for surgical removal of the gonads. It is amazing how a patient with severe adrenal insufficiency can withstand 36 years of her life undiagnosed without going into an adrenal crisis. Her tall stature and acromegalic features were the striking signs confusing all physicians and delaying the correct diagnosis and appropriate treatment. There has been reported worldwide, nearly 120 cases with documented severe 17-alpha-hydroxylase deficiency. To our knowledge this is the first case identified in Puerto Rico of male pseudohermaphroditism secondary to 17-alpha-hydroxylase enzyme deficiency.

Acromegaly↗