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Biomedical subjects

D W Hamilton

Publications and source records attributed to D W Hamilton.

At least 37 records · Page 2Linked to original sources
PubMed1994

Laparoscopic versus open appendicectomy for suspected appendicitis: a prospective study.

Despite recent advances in minimally invasive surgery, laparoscopic appendicectomy has been questioned as a feasible method of treating patients with suspected appendicitis because open appendicectomy carries few risks and complications. Between February 1992 and January 1993 a non-randomized prospective study comparing open and laparoscopic appendicectomy was designed to assess differences in postoperative morbidity, pain, inpatient hospital stay and a return to normal lifestyle. One hundred and sixty-seven patients with suspected clinical appendicitis were assigned to open (n = 74) or laparoscopic (n = 93) appendicectomy. Six patients were excluded due to the presence of other significant pathology such that the appendix was not removed. Eighty-seven patients underwent attempted laparoscopic appendicectomy, of which 81 were completed. The diagnosis of appendicitis was confirmed histologically in 63.5% of patients undergoing open appendicectomy and 63% of patients undergoing laparoscopic appendicectomy. There were no significant differences in anaesthetic times, postoperative morbidity and analgesic requirements. There was a significant reduction in both postoperative inpatient stay (P < 0.0001) and time taken to return to work or normal activities (P < 0.0001) for the laparoscopic group. The use of laparoscopy for patients with suspected appendicitis aids definitive diagnosis and should reduce the negative appendicectomy rate to an acceptable figure. The results suggest that laparoscopic appendicectomy is safe and offers advantages over open appendicectomy in the management of patients with suspected appendicitis.

Adolescent↗
PubMed1993

Improved preservation of rat epididymal sperm for high-resolution low-voltage scanning electron microscopy (HR-LVSEM).

Various fixation protocols were used in an attempt to improve preservation of rat epididymal sperm for high-resolution low-voltage scanning electron microscopy (HR-LVSEM). Wash solutions and fixatives of different composition and osmolarity were tested. Paraformaldehyde and glutaraldehyde concentrations were varied between 0.5% and 3%. Ruthenium red was tested as an additive in both primary fixation and postfixation, or in postfixation alone. HR-LVSEM revealed various degrees of ruffing, folding, blebbing, and peeling off of the plasma membrane, as well as holes of different sizes. The plasma membrane overlying the acrosome and the connecting piece proved to be particularly sensitive to varying fixation conditions. Consistent topographical differences were revealed among the different domains over the sperm head. Most of the differences were considered to be artifacts. Their consistency, however, suggests that structural and biochemical differences exist either within the membrane or in the structures subjacent to the membrane. Primary fixation turned out to be less critical than postfixation. Preservation of a smooth plasma membrane without holes could only be achieved when primary fixation in low aldehyde concentrations, with or without ruthenium red, was followed by postfixation with OSO4 and 1,000 ppm ruthenium red. Examination of thin sections of the same material confirmed that even a considerable number of small holes are difficult to detect in transmission electron microscopy. These results show that with the recent increase in resolution of LVSEM there is need for further effort to improve sample processing.

Animals↗
PubMed1992

Immunodetection after complete destaining of coomassie blue-stained proteins on immobilon-PVDF.

A technique that simplifies the localization of an immunodetectable protein in relation to the other electrophoresed proteins is described. Proteins are transblotted onto a polyvinylidene difluoride (PVDF) membrane and visualized by staining with Coomassie brilliant blue R-250, and a photograph of the protein pattern is taken. The Coomassie blue-stained PVDF membrane is then completely destained using a 25% acetic acid/50% methanol solution that allows subsequent immunostaining on the same membrane. The technique uses common laboratory reagents, is rapid, and has been shown to be applicable for a variety of proteins using both monoclonal and polyclonal antibodies and a variety of transblots.

Animals↗
PubMed1992

A safe, new approach to establishing a pneumoperitoneum at laparoscopy.

The traditional method of establishing a pneumoperitoneum before laparoscopic surgery is via a Verres needle inserted in the midline below the umbilicus while tenting the abdominal wall with the hand. A new approach is described in which preliminary surgical exposure and tenting of the linea alba immediately above the umbilicus is achieved before needle insertion through the superior margin of the umbilical ring. The advantages of this new technique over the conventional method are discussed. Further technical features important in the safe formation of the pneumoperitoneum are emphasized.

Adolescent↗
PubMed1990

Analysis of major androgen-regulated cDNA clones from the rat epididymis.

Four abundant cDNA clones have been isolated from a rat epididymal cDNA library. Northern blot analysis has shown that these clones partially encode 4.5 kb, 2.8 kb, 1.2 kb and 0.85 kb mRNAs and that their expression is not detectable in total RNA preparations from heart, kidney, liver or testis. Fourteen days after castration the levels of the 2.8 kb, 1.2 kb and 0.85 kb transcripts were greatly reduced whereas the 4.5 kb mRNA was undetectable. Subsequent treatment of castrated rats with testosterone for 1 day resulted in a complete restoration of the pre-castration steady-state levels of the 2.8 kb and 0.85 kb mRNAs, restoration of the 4.5 kb mRNA to 70% of pre-castration levels, and a slight over-induction of the 1.2 kb mRNA. Analyses of separate regions of the epididymal tract showed that expression of the 2.8 kb and 1.2 kb mRNAs increased towards the distal end of the epididymis, while the 4.5 kb and 0.85 kb transcripts were primarily synthesised in the caput region.

Amino Acid Sequence↗
PubMed1990

An 18-kDa androgen-regulated protein that modifies galactosyltransferase activity is synthesized by the rat caput epididymidis, but has no structural similarity to rat milk alphalactalbumin.

Galactosyltransferase and alphalactalbumin-like activities have been reported to be present in the post-testicular fluids of the male reproductive tract. In the lactating mammary gland, these activities constitute the lactose synthetase complex. Kinetic parameters and acceptor specificities previously reported, along with recent amino acid sequence analysis argue against the mammary gland and epididymal activities being products of the same gene. In this paper we present cell-free translation of rat epididymal mRNA and Northern blot analysis of epididymal mRNA hybridized with authentic rat alpha-lactalbumin cDNA supporting this lack of identity and describe the differential synthesis and secretion of the androgen-regulated 18 kDa component of the so-called rat epididymal alphalactalbumin-like complex along the length of the epididymis. We conclude that although the 18 kDa component of the so-called epididymal alphalactalbumin moiety (E alpha LA) is capable, in common with a number of unrelated molecules, of modifying galactosyltransferase acceptor specificity in vitro, there is no primary structural similarity between it and authentic rat mammary alphalactalbumin. In view of the fact that the activity of E alpha LA is 1/100th that of authentic milk alphalactalbumin, we suggest that it may not be of physiological importance and that modification of galactosyltransferase activity may not be the function of the 18 kDa molecule.

Amino Acid Sequence↗
PubMed1989

The major maturation glycoprotein found on rat cauda epididymal sperm surface is linked to the membrane via phosphatidylinositol.

The experiments reported here further characterize a approximately 26[3H] kD cell surface glycoprotein that can be detected on rat cauda epididymal sperm using the galactose oxidase/NaB[3H]4 technique (1). When labeled sperm are treated with PI-PLC the 26[3H] kD is completely released from the cell. The released molecule can be recovered undegraded from incubation supernatant. Release by PI-PLC converts the hydrophobic, membrane-anchored form into a hydrophilic molecule as assessed by partition studies using Triton X114. Isoelectric focusing studies using both untreated (control) and PI-PLC treated samples shows that there is charge heterogeneity with two major peaks at pls of approximately 5.0 and approximately 4.5. We also show for the first time that the molecule persists on ejaculated cells.

Animals↗
PubMed1987

Preliminary observations on a second Mr approximately equal to 24,000 membrane molecule from rat spermatozoa.

Preliminary data are presented to show that the integral membrane glycoprotein found on rat cauda epididymal spermatozoa is one of two Mr = approximately 24,000 molecules that are associated with sperm membranes. The second molecule can be differentiated from the glycoprotein by a variety of antibodies and can be shown to be present in spermatozoa and in residual bodies present in the epididymal fluid. The second molecule can be localized immunocytochemically in spermatids and Leydig cells in the testis.

Cell Membrane↗
PubMed1986

Membrane glycoproteins from spermatozoa: partial characterization of an integral Mr = approximately 24,000 molecule from rat spermatozoa that is glycosylated during epididymal maturation.

Spermatozoa from the rat cauda epididymidis were treated with either the galactose oxidase-NaB[3H]4 or the NaIO4-NaB [3H]4 technique to label cell surface moieties of galactose and sialic acid, respectively. Following extraction with 40 mM octyl-beta-D-glucopyranoside (OBG), electrophoresis in sodium dodecylsulfate-polyacrylamide gels (SDS-PAGE) revealed a single radioactive peak migrating at Mr = approximately 24,000 in 11.2%, 14% and 16.8% tube gels. SDS-PAGE of the same OBG extract on 5.6% and 14% gels showed that this molecule was the same as that reported elsewhere, having a molecular weight varying from 32,000 to 37,000. The amount of labeled molecule extracted with 8 M urea or with 6 M guanidine-HCl was 30 and 50%, respectively, of that achieved with OBG. However, when labeled sperm were treated under other conditions (at pH 8, pH 3, 0.1-3 M NaCl [at pH 7.2], 5 mM ethylenediaminetetraacetic acid [EDTA], 20-200 mM dithiothreitol or 20-200 mM betamercaptoethanol, at varying temperatures and extraction times), the amount of labeled molecule extracted was less than 1% of that obtained with OBG. The molecule aggregates in aqueous buffers, as shown by chromatography using Sephadex G-100 and by centrifugation through a sucrose density gradient. Analysis by charge-shift electrophoresis suggested that the molecule contains an exposed hydrophobic domain(s). Mild trypsin treatment released all the labeled carbohydrate with the majority of the label attached to a Mr = 10,000 fragment. These data support the hypothesis that the molecule is an integral membrane glycoprotein, and suggest that it is only partially buried in the lipid matrix of the plasma membrane.

Animals↗
PubMed1986

Immunohistochemical localization of alphafoetoprotein in testes of mouse embryos at 17 days of gestation.

Immunohistochemistry was used to localize alphafoetoprotein (AFP) in 1 micron plastic sections of embryonic testes in order to investigate the cellular basis of AFP production in murine teratocarcinomas. Atypical germ cells and scattered foci of normal germ cells were AFP-positive in both tumour-susceptible and control animals. AFP could not be demonstrated, however, in tumour stem cells. These results suggest that AFP may be a marker for the endodermal origin of germ cells.

Animals↗
PubMed1986

Morphologic analysis of spontaneous teratocarcinogenesis in developing testes of strain 129/Sv-ter mice.

Spontaneous teratocarcinogenesis in the mouse testis begins during the early stages of gonad differentiation. Using inbred strain 129/Sv-ter mice which are highly susceptible to these tumors, the authors have examined the morphologic features of the testis during the gestational period defined from Day 13 through birth. Normal inbred mice (129/J) and random bred mice (Swiss Webster, SW) were used as control groups. Serially sectioned gonads were evaluated at the light- and electron-microscopic levels for histologic changes. In agreement with studies by other workers, embryonal carcinoma cells (ECCs) were observed in tumor-susceptible mice. Cellular arrangements varied from vesicular to nodular. Cell death within advanced tumors was labeled "apoptosis" (shrinkage necrosis). Also encountered were syncytial arrangements of gonocytes (atypical gonocytes), which were present in all animal groups. The significance of atypical gonocytes in relation to degeneration and preneoplasia is addressed.

Animals↗
PubMed1985

Synthesis and secretion of proteins by perifused caput epididymal tubules, and association of secreted proteins with spermatozoa.

We have used perifusion organ culture of proximal and distal caput epididymal tubules of the rat to study the secretion of proteins by epididymal epithelium and uptake of the luminal radioactive proteins by sperm. The amount of incorporation of L-[35S]methionine into luminal fluid proteins was time dependent and completely inhibited by cycloheximide. The association of labeled proteins with cultured sperm was also dependent on time and continuous, with sperm still acquiring labeled luminal proteins after protein synthesis was arrested. A Mr = 46,000 molecule was found to be heavily labeled in luminal fluid and sperm extracts. Fluorograms of all L-[35S]methionine extracts immunoprecipitated using an antiepididymal alpha-lactalbumin antibody (Klinefelter and Hamilton, 1984) showed labeling of an Mr = 18,000 molecule and, in addition, the Mr = 46,000 molecule, but immunostaining was specific only for the Mr = 18,000 molecule and the heavy chain of the immunoglobulin. We suggest that the Mr = 46,000 molecule may be galactosyltransferase. Galactose oxidase-NaB[3H]4 labeling of the cultured caput sperm cell surface revealed a Mr = 23,000 molecule that was able to be immunoprecipitated with antiepididymal alpha-lactalbumin antibody. Our data suggest that this cell surface molecule is similar to one component of the fluid epididymal alpha-lactalbumin-like complex and, in addition, show that glycosylation of the sperm surface can occur in the caput epididymidis.

Animals↗
PubMed1984

Synthesis and secretion of proteins in vitro by isolated epithelial strips from the proximal and distal vas deferens of the rat.

Epithelial strips of rat vas deferens were isolated by a new technique and used to study differences in protein synthesis and secretion between morphologically defined segments of the vas deferens. The isolated strips were viable as judged by linear oxygen uptake over the incubation period and by preservation of structure. Epithelium from the proximal vas deferens incorporated more labelled amino acids into cytosolic (P less than 0.02) and incubation medium (P less than 0.01) proteins than did epithelium from distal vas deferens; this incorporation was inhibited by cycloheximide. Although some of the incubation medium proteins arose by leakage from damaged cells, specific protein secretion was indicated by differences in SDS-PAGE autoradiogram banding patterns and by differences in glycosylation between proteins in the incubation medium and those in the cytosol. Thus, the former contained more label from [14C]galactose incorporation than did cytosolic proteins (proximal: P less than 0.05; distal: P less than 0.005).

Amino Acids↗
PubMed1984

The effect of experimentally induced diabetes on the metabolism of glucose by seminiferous tubules and epididymal spermatozoa from the rat.

The concentration of glucose in the plasma of alloxan-diabetic rats was 23.4 +/- 0.86 mM (mean +/- SEM; n = 18), and the concentration of insulin was 11.4 +/- 1.67 microU/ml (mean +/- SEM; n = 17). The weights of the ventral prostate (0.45 +/- 0.03 vs. 0.72 +/- 0.04 g) and seminal vesicles (1.23 +/- 0.06 vs. 1.84 +/- 0.08 g) were decreased compared to control values and the rats lost body weight, but the weights of the testes were not significantly different from control values (3.14 +/- 0.08 vs. 3.23 +/- 0.14 g/pair). Similar changes were seen in streptozotocin-diabetic rats. The concentration of fructose (micromoles per g fresh wt) was greater in the coagulating gland of alloxan-diabetic (19.6 +/- 1.3; n = 17) than control rats (9.1 +/- 0.7; n = 18). The production of 14CO2 from D-[U-14C]glucose by spermatozoa or seminiferous tubules from diabetic rats was decreased compared to that in controls [28 +/- 3 vs. 53 +/- 6 nmol glucose converted/10(8) spermatozoa X 30 min (n = 8) and 0.81 +/- 0.03 vs. 1.08 +/- 0.03 mumol glucose converted/g fresh wt X 30 min (n = 7)]. There was no change in the production of lactate or 3HOH from D-[2-3H] glucose, and the presence of insulin (10 mU/ml) in the incubation had little effect. Rat epididymal spermatozoa took up 2-deoxy-D-glucose by a facilitated diffusion mechanism; the Km was about 0.2 mM, with a maximum velocity of about 0.10 nmol/10(6) spermatozoa X 10 sec. Neither alloxan-diabetes nor the presence of insulin (10 mU/ml) had an appreciable effect on these parameters.

Alloxan↗
PubMed1983

Gastric duplication in an adult.

Congenital alimentary duplications occur most commonly in relation to the ileum and are rare in the region of the stomach. A case of gastric duplication presenting in an adult and visualized on computed tomography is reported.

Adult↗
PubMed1983

Rapid compensatory hypertrophy of the lamb testis after neonatal hemiorchidectomy: endocrine and light microscopical morphometric analyses.

The testis mass of lambs hemiorchidectomized (HO) within 1 week of birth exceeded that of control testes by 23%, 67%, and 114% at 4, 8, and 12 weeks; the epididymis was 39% heavier than control epididymides by 12 weeks. The seminiferous tubular mass in HO testes grew at a faster rate than in control testes to achieve full compensation by about 10 weeks; Sertoli cell division was augmented in the 1- to 4 week phase and Sertoli cell cytoplasm increased throughout. The major growth response of the interstitium of HO testes occurred in the 1- to 4 week period but did not obtain full compensation by 12 weeks; the vascular component responded to HO by rapid growth in the 8- to 12 week period. There was a low incidence of division amongst gonocytes (prespermatogonia) in both groups of lambs but at 12 weeks spermatogonial mitoses, spermatocytes, and tubular lumina were present in four out of four HO tests but only one of three control testes. In the same lambs, HO induced an immediate increase in circulating plasma concentrations of FSH to 3-4 x control values at 8 weeks, which were then suppressed to near control values by 10 weeks. Apart from transient increases in LH (at 4-5 weeks) and testosterone (6-7 weeks) above control values, there were no differences between HO and control lambs in the circulating concentrations of any other hormone measured (LH, GH, TSH, PRL, and testosterone). The evidence suggests that the major prepubertal influence on testicular development and growth in lambs is the FSH-provoked response of the Sertoli cells.

Animals↗