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Biomedical subjects

B T Hinton

Publications and source records attributed to B T Hinton.

At least 55 records · Page 3Linked to original sources
PubMed1981

Effects of obstruction of the flow of seminiferous tubule fluid on the germinal epithelium in the rat.

Blocking the lumen of a single seminiferous tubule by introducing a plug of non-toxic latex produced a lesion in that tubule, but not in immediately adjacent tubules. The lesion extended for up to 50 mm from the end of the latex. Nearest to the block the tubule was completely aspermatogenic; further along the tubule, the lesion was less severe, involving disorganization and reduction in germ cell numbers, with the cells showing vacuolation, pycnosis and karyolysis. Binucleate and giant cells were common, and cells were often exfoliated into the lumen. The lesion tended to increase in length with longer times after introduction of the plug, but there appeared to be no preferential involvement of the shorter segment of the tubule between the block and the rete. The transition from damaged to healthy tubule was abrupt.

Animals↗
PubMed1980

Concentrations of myo-inositol in the luminal fluid of the mammalian testis and epididymis.

The concentration of free myo-inositol was measured in the luminal fluid removed by micropuncture from the testis and epididymis of rat, hamster, rabbit, rhesus monkey, baboon, ram and boar. The highest concentration (mM) was found in the epididymal luminal fluid from the cauda epididymidis of the hamster (90) and the rat (50), and the lowest was seen in the rabbit (< 0.5), and boar (1.0-1.2), whilst the rhesus monkey (17), the baboon (1.3) and the ram (0.9-5.9) were intermediate. The species also differed with respect to the changes in luminal inositol coicentration along the epididymis.

Animals↗
PubMed1980

Concentrations of glycerophosphocholine, phosphocholine and free inorganic phosphate in the luminal fluid of the rat testis and epididymis.

Measurements were made on micropuncture samples of luminal fluids. The concentration of GPC was highest in the caput and corpus regions of the epididymis, that of phosphocholine changed little along the length of the rat epididymis and there was approximately a 3-fold increase of concentration of inorganic phosphate in the luminal fluid from caput epididymidis to ductus deferens. The estimated total phosphate appeared to equal that of the sum of the phosphate derived from the above compounds. The concentrations of these compounds in the luminal fluid of the testis and in blood plasma were very low.

Animals↗
PubMed1980

The epididymal microenvironment: a site of attack for a male contraceptive?

During their development, spermatozoa are continually bathed in fluid provided by epithelial secretions of the seminiferous tubule and the epididymal duct. This fluid or microenvironment is probably very important for spermatozoal maturation and survival. Micropuncture and microanalytic studies have revealed the occurrence of several biochemical changes of this specialized microenvironment along the epididymal duct; these changes seem to be linked to sperm maturation. The interactions between maturing spermatozoa and their microenvironment must be understood before interference in sperm maturation through intervention of the formation of the microenvironment is possible. Several compounds have been shown to interfere in spermatozoal maturation in the epididymis although their use as male contraceptives requires further investigation.

Animals↗
PubMed1979

Measurement of the motility of rat spermatozoa collected by micropuncture from the testis and from different regions along the epididymis.

Spermatozoa from the testis and various regions along the epididymis of the rat were collected by micropuncture and their motility after dilution was estimated over a 15-min period by using a Quantimet image analyser. The motility of sermatozoa from the rete testis and seminiferous tubules was too low to be measured. The estimate of motility of spermatozoa from the proximal caput epididymidis was much lower than that of spermatozoa from the other regions. Spermatozoa from the distal part of the caput showed sustained motility for 15 min, whereas those from the caudal region and ductus deferens, although active initially, became less active during this period.

Animals↗
PubMed1979

The concentration of carnitine in the luminal fluid of the testis and epididymis of the rat and some other mammals.

Luminal fluid was collected by micropuncture techniques from the testis and epididymis of the rat, hamster, rabbit, boar and ram and the concentration of free L-carnitine in the fluid was estimated using enzymic methods. Carnitine was present in the testicular fluid of the rat in concentrations less than 1 mM but increased down the epididymis to reach 53 mM in luminal fluid from the cauda epididymidis, approximately 2000 times higher than in blood plasma. A high concentration was first found in the luminal fluid from the distal caput epididymidis, at about the point where the spermatozoa become motile. Carnitine was also present in the epididymal luminal fluid of the other species studied; the amounts were not as high as those in the rat but were still higher than those in blood plasma.

Animals↗
PubMed1976

The restricted penetration of iodinated rat FSH and LH into the seminiferous tubules of the rat testis.

The penetration of 125I-iodinated rat follicle-stimulating hormone (FSH; labelled by three different techniques) and luteinizing hormone (LH) through the walls of the seminiferous tubules of the rat testis has been studied by injecting the labelled hormone into rats with the efferent ducts of one testis ligated 16 h before the collection of samples of blood and tissues. The concentration of trichloracetic acid-precipitable and immunoprecipitable radioactivity was measured in blood plasma and rete testis fluid and calculated for the total secreted fluid retained in the testis by the ligature, and for the additional tubular fluid from the ligated testis, separated by centrifugation after decapsulating the testis and dispersing the cells. Very little intact hormone penetrated into the testicular fluids, even 16 h after injection of the labelled hormone, and the volume of distribution in the unligated testis of the trichloracetic acid-precipitable radioactivity was only slightly greater than that for markers known to be confined to the extracellular interstitial fluid. This suggests that the labelled hormones do not penetrate readily through the walls of the semiferous tubules into their lumina. Injected inorganic iodiide and trichloracetic acid-soluble 125I-circulating after the injection of iodinated hormones penetrated more rapidly into the tubules, but had not reached equilibrium between the testicular fluids and blood plasma 16 h after injection. Labelled FSH was reasonably stable in the circulation after injection, but 80% of the 125I was not protein-bound 16 h after injection of labelled LH.

Animals↗
PubMed1976

Specificity of sugar transport across the brush border of the rat proximal tubule.

By chemical and electrical measurements the transport of 25 sugars in the proximal tubule of the rat kidney was investigated. The data gained reveal the following structural requirements for the D-glucose transport system in the renal brush border: A free OH in the D-gluco-configuration on C atom 2 is most important - OH in equatorial position of the chair Cl conformation -. A free OH on C-3 in the equatorial configuration is also essential. If the OH on C-4 turns from the equatorial to the axial configuration the transport is 50% reduced. The OH on C-6 may be missing if otherwise the D-glucose configuration is unchanged. But if in addition the position of OH in C-4 has changed the transport ceases. Furthermore the presence of a C-6 atom and of a ring structure is necessary.

Animals↗
PubMedDate not supplied

The male antifertility agents alpha chlorohydrin, 5-thio-D-glucose, and 6-chloro-6-deoxy-D-glucose interfere with sugar transport across the epithelium of the rat caput epididymidis.

The effects of the male antifertility agents alpha-chlorohydrin, 5-thio-D-glucose, and 6-chloro-6-deoxy-D-glucose on sugar transport (3H-3-O-methyl-D-glucose and 3H-2-deoxy-D-glucose) across the rat caput epithelium was studied in vivo and in vitro. The compound alpha-chlorohydrin reduced sugar transport uptake in vivo but not in vitro, whereas 5-thio-D-glucose and 6-chloro-6-deoxy-D-glucose were both effective in vivo and in vitro. The mechanism of action of these compounds on sugar movement across the caput epithelium is probably complex. Direct competition for the glucose carrier situated on the basolateral membrane and intratubular effects are suggested. Thirty-day injections of 5-thio-D-glucose or alpha-chlorohydrin did not have adverse effects on sugar transport or the permeability of the blood-testis and blood-epididymis barriers as assessed by an in vitro technique.

Animals↗
PubMedDate not supplied

Regional differences in luminal fluid polypeptides of the rat testis and epididymis revealed by two-dimensional gel electrophoresis.

Luminal fluid samples were collected by micropuncture of the seminiferous tubule, rete testis, and defined levels of the epididymal tubule. After removal of spermatozoa by centrifugation, the supernatant fluids were analyzed by two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) and an ultrasensitive silver staining procedure to define the sequential change in protein composition along the excurrent duct system. Fluid from each segment displayed a characteristic 2-D PAGE map composed of numerous polypeptides. Seminiferous tubule fluid contained a wide array of polypeptides, with most concentrated in the 45 Kd to 90 Kd range, but, in contrast, rete testis fluid lacked most of these polypeptides. The major complex of rete testis fluid comigrated with serum albumin and was present in all distal segments. Other major rete testis components were not noted distally. Fluid from the caput was characterized by new major components of 30 to 37 Kd, 28 to 30 Kd, 24 Kd, and 23 Kd, each of which consisted of multiple spots of apparent isoelectric variants; all except the 30 to 37 Kd complex were present in the fluid from more distal segments. Proceeding distally, there was a temporal appearance of new polypeptides, especially in the molecular weight range below 30 Kd. Two-dimensional PAGE analysis of detergent extracts of washed spermatozoa indicate that a specific subset of these fluid polypeptides are sperm associated.

Animals↗
PubMedDate not supplied

Selective luminal absorption of L-carnitine from the proximal regions of the rat epididymis. Possible relationships to development of sperm motility.

The absorption of L-carnitine from the duct of the proximal regions of the rat epididymis was investigated using a stopped-flow, split-droplet microperfusion technique. L-carnitine was absorbed from the duct of the proximal caput epididymidis by a time-dependent and saturable transport system (Km = 25 micron; Vmax = 0.65 pmoles absorbed/min/mm3 tubular volume). Furthermore, absorption appeared to be primarily sodium-independent, although the existence of a minor sodium-dependent pathway cannot be ruled out. A similar transport system was not evident along the distal caput epididymidis, where absorption of L-carnitine was attributable to passive diffusion only. The inward and outward movement of L-carnitine across the epithelium of the proximal and distal caput epididymidis appears to be regulated so that the spermatozoa come into contact with high levels of L-carnitine in the distal caput region.

Animals↗
PubMedDate not supplied

The testicular and epididymal luminal amino acid microenvironment in the rat.

Concentrations of amino acids were measured in arterial and testicular venous blood, and in fluids from the seminiferous tubule, rete testis, and the caput, corpus, and cauda epididymidis. There were no significant differences in the concentrations of any amino acids between arterial and testicular venous blood, whereas there were significant differences between arterial/venous blood and testicular interstitial fluid. The predominant amino acids measured within seminiferous tubule fluid (STF) and rete testis fluid (RTF) were glycine, alanine, glutamate, and glutamine. RTF contained approximately equal concentrations of basic and total amino acids, but 17 times higher acidic amino acids and 1.2 and 1.3 times lower uncharged polar and nonpolar amino acids, respectively, compared to STF. The concentration of total amino acids within caput fluid reached over 50 nmol/L, but then declined to approximately 50% and 0.1% of caput for corpus and cauda, respectively. The predominant amino acids measured within epididymal luminal fluids were glutamate and taurine; glutamate contributed to approximately 90% of the total amino acids measured in caput fluid. The presence of glutamate and taurine within the epididymal lumen is due primarily to a direct contribution from the epididymal epithelium, as measured using the split-drop stopped-flow microperfusion technique. Several other amino acids within the lumen also originate from the epididymal epithelium. Amino acids contribute approximately 20%, 9%, and 2% of the total osmolality of caput, corpus, and cauda fluid, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗