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Biomedical subjects

W D Smith

Publications and source records attributed to W D Smith.

At least 109 records · Page 6Linked to original sources
PubMed1985

Infertility in mice after unilateral vasectomy.

The effects of unilateral vasectomy upon fertility and antisperm antibody production were studied using DBA/1J mice. Thirty-six males underwent either unilateral vasectomy, unilateral orchiectomy, or sham surgery. In vivo effects upon fertility were monitored by matings. Antisperm antibody titers were measured monthly. In vitro fertilization was performed in the presence of serum obtained 4 months postoperatively, and serum testosterone levels were also determined. After 3 months, only 1 male in the vasectomy group induced a pregnancy (1 of 12), while all but 1 of the males in the two control groups induced a pregnancy (20 of 21). The geometric mean antisperm antibody titer was 1:169 in the vasectomy group, while the orchiectomy and sham surgery groups had titers of 1:4 and 1:14, respectively (P less than 0.0001). The percentage of eggs fertilized in vitro in the presence of serum from experimental mice fell from 80% in the two control groups to 40% in the unilateral vasectomy group. Unilateral vasectomy induced infertility in DBA/1J mice and an antisperm antibody response. Sera containing these antibodies inhibited in vitro fertilization. This suggests that infertility after unilateral vasectomy may be immunologically mediated by antisperm antibodies.

Animals↗
PubMed1985

Effect of Ostertagia ostertagi on lamb performance and cross resistance to O circumcincta.

Fifteen worm-free lambs (two-and-a-half to three months or four to four-and-a-half months old) were infected with 3500 or 4000 Ostertagia ostertagi larvae on five days each week for six weeks, and their performance compared to that of controls. Eleven lambs were killed after eight weeks and four were challenged with O circumcincta to determine whether any cross resistance had developed. A feature of the O ostertagi infection was the considerable variation in response. Overall liveweight gain was lowered by 24 per cent in the two-and-a-half to three-month-old infected lambs, mainly due to reductions of 27 to 40 per cent in four of the seven lambs. There was no consistent effect in the older lambs. The worm populations consisted mainly of early fourth stage larvae and developing worms, but a small percentage reached sexual maturity and these produced a low faecal egg count (1 to 63 eggs per gram). Numerous intraluminal refractive crystals were present in the gut of both adult worms and developing stages, possibly reflecting degenerative changes. Hypertrophy of the abomasal mucosa with patchy loss of differentiation was a feature of the infection, and in four lambs serum pepsinogen concentrations were elevated. Exposure to O ostertagi did confer some protection against challenge with O circumcincta in that worm counts were reduced to about 60 per cent of those in controls, although no increase was observed in the numbers of arrested larvae. The successful passage of O ostertagi through young lambs could be important in mixed or alternate grazing systems by providing a reservoir of infection for the alternate host.

Animals↗
PubMed1984

Manifestations of resistance to ovine ostertagiasis associated with immunological responses in the gastric lymph.

Groups of previously infected and worm-free sheep were serially killed up to 10 days after challenge with 50 000 Ostertagia circumcincta larvae. Two similar groups of sheep were killed 10 days after challenge with 1000 larvae. The previously infected sheep were resistant to the smaller challenge dose in that fewer, stunted worms were recovered from them than from controls. However, this resistance was not as marked as that observed in the previously infected sheep which received the large challenge, because proportionally fewer worms were recovered after the 50000 dose and the great majority of these were arrested at the early fourth stage. The gastric lymph ducts of 6 previously infected sheep were cannulated successfully and a marked local immune response was detected in 3 sheep which were challenged with 50 000 larvae. No response was detected in 3 cannulated sheep challenged with 1000 larvae. In the lymph of the 50 000 dose group, a temporary increase in pepsinogen activity suggested that a hypersensitivity reaction related to the presence of large numbers of mucosal mast cells began between 24 and 48 h after challenge. This was followed by marked increases in the cellular and IgA content of lymph, which reached peaks on days 3 and 6, respectively. It is suggested that the response detected in the gastric lymph reflected aspects of a local immune reaction in the abomasal mucosa and that this reaction accounted for the enhanced degree of resistance to the larger challenge dose.

Animals↗
PubMed1984

Ultrastructural sperm tail defects associated with sperm immotility.

Four individuals with a complaint of infertility were evaluated after a semen analysis had demonstrated no motility. The semen analyses were otherwise normal, with the exception of a low count in one subject. All had normal percentages of living sperm. One of the individuals had chronic respiratory disease, and two others had a previous history of genitourinary infection and/or testicular injury. Three subjects possessed antisperm antibodies. Electron microscopy revealed a multiplicity of sperm tail structural defects seen in all specimens. Some of these data support the concept of acquired immotile sperm syndrome(s) with ultrastructural defects, as contrasted with the usual congenital forms of the immotile-cilia syndrome.

Adult↗
PubMed1984

Comparison of saline incubation and pepsin digestion as methods for recovering Ostertagia circumcincta larvae from the abomasum of sheep.

Incubation in saline at 37 degrees C was compared with pepsin digestion as a quantitative method for recovering larval stages of Ostertagia circumcincta from the abomasal mucosa of sheep. Experiments showed that the techniques were of roughly similar efficiency even when the larvae were arrested but that the saline method was preferable because worm searching was easier and quicker.

Abomasum↗
PubMed1984

Resistance to Haemonchus contortus transferred between genetically histocompatible sheep by immune lymphocytes.

The pattern of faecal egg counts after infection with 10,000 Haemonchus contortus larvae was similar within but not between, four pairs of monozygous twin sheep. Transfer of whole lymph or washed lymph cells from three immune donor sheep to their identical co-twin recipients reduced the susceptibility of the recipients to challenge with 10,000 larvae as measured by faecal egg counts. Cells from a nonimmune donor did not have this effect. In a final experiment, washed cells from an immune triplet sheep, which was actively responding to a repeated challenge infection, transferred a secondary local IgA response to a second recipient triplet and resulted in a marked reduction in worm count when compared with that of a third infectivity control triplet.

Animals↗
PubMed1983

Studies on the local immune response of the lactating ewe infected with Ostertagia circumcincta.

Changes in the flow and composition of gastric lymph were monitored in groups of lactating and non-lactating ewes which were repeatedly infected with Ostertagia circumcincta. As judged by faecal egg counts and worm burdens the lactating group was more susceptible than the non-lactating controls to the challenge infection. Increased amounts of pepsinogen as well as larger numbers of eosinophils and neutrophils entering the gastric lymph indicated considerable abomasal damage and inflammation in the lactating ewes. However, measurement of the flow of lymphocytes as well as the amount of IgA and IgA antibody in the lymph did not indicate that these aspects of the local immune response were impaired during lactation; in fact the output of IgA-containing lymphocytes as well as IgA itself was usually raised in the lactating sheep. Lymph flow was increased and lymph globulin concentrations proportionally decreased in lactating ewes, irrespectively of whether they were infected with worms. It is suggested that these changes were caused by the increase in voluntary food intake which occurs during lactation.

Animals↗
PubMed1983

Local immunity and Ostertagia circumcincta: changes in the gastric lymph of sheep after a primary infection.

Some aspects of the kinetics of the primary local immune response to O. circumcincta were studied by monitoring the flow and composition of gastric lymph from 4 sheep for 3 weeks after infection with 50 000 larvae. A significant increase in the frequency of lymphoblasts in the lymph showed that all the sheep were responding immunologically to the parasites from day 8 onwards. However, considerable individual variation in degree and timing was evident in other aspects of the immune response; 2 animals responded with large increases in lymphocyte output which reached a peak on day 5 or day 10, whereas the main response in the other 2 sheep appeared to be inflammatory in nature, with large increases in lymph flow and eosinophil output which occurred during the third week of infection. No significant changes in the content of IgA or IgA anti-worm antibody were detected in the lymph, but pepsinogen concentrations were significantly raised from day 12 onwards.

Animals↗
PubMed1983

Local immunity and Ostertagia circumcincta: changes in the gastric lymph of immune sheep after a challenge infection.

Immunity to Ostertagia circumcincta was demonstrated in 5 previously infected sheep which were killed 10 days after challenge with 50 000 larvae. This immunity was expressed as a reduction in the number as well as the degree of development of the surviving parasites compared with those found in 6 control sheep. Gastric lymph was sampled from the immune group from 2 days before till 10 days after challenge and a secondary local immune response was detected. The main features of this response were a large increase in cell output in the lymph, especially in lymphoblasts and IgA-containing cells, which reached a peak on day 4 or 5, followed by a ten-fold increase in IgA immunoglobulin and IgA anti-worm antibody which reached a peak 7 or 8 days after challenge. The timing of these events suggested that the cellular, but not the IgA, response could have been involved in a putative mechanism which caused arrested development, although both components could have been implicated in mechanisms which may have caused expulsion of developing larvae.

Animals↗
PubMed1983

Selection of human spermatozoa according to their relative motility and their interaction with zona-free hamster eggs.

Human spermatozoa were separated according to their motility by centrifuging semen on discontinuous Percoll gradients. Fractions of the gradients were examined for sperm motility, velocity, viability, morphology, bacteria, and sperm function using the hamster ova sperm penetration assay. The percentage of motile sperm increased from 40% to 60% motile sperm in 60% Percoll to 90% to 100% Percoll. Sperm velocity increased proportionately. Staining showed that greater than 90% of sperm in the 100% Percoll were alive and had normal morphology, and that only sperm cells were found in Percoll concentrations greater than 80%. Sperm isolated in the 80% to 100% Percoll fractions penetrated hamster ova much more frequently than sperm found in the 60% to 70% fractions or than sperm that had not been separated on a Percoll gradient.

Cell Separation↗
PubMed1982

Benefits of the sperm (hamster ova) penetration assay in the evaluation of the infertile couple.

The males of 310 infertile couples and 30 control couples (current pregnancy) were evaluated with the sperm (hamster ova) penetration assay (SPA) and seminal fluid analysis (SFA). The SPA was found to have a sensitivity of 100% and a specificity of 97% compared to 41% and 90%, respectively, for the SFA. The highest degree of concordance of the two tests existed when both tests were abnormal and no female factor was identified. The poorest concordance occurred when the SFA was normal and no female infertility factor was identified. In almost all cases of unexplained infertility where no female infertility factor was present, the problem could be assigned to the man, as evidenced by an abnormal SPA. The SFA seemed to have some predictive value with respect to the outcome following treatment of the man.

Animals↗
PubMed1982

A flexible system for closed-loop ventilator development.

The feasibility of using a microcomputer to regulate the delivery of artificial ventilation was investigated experimentally. To carry out this study, a sampled-data proportional, integral, derivative feedback controller was implemented on a commercial microcomputer and interfaced with a digital/analogue model of a prototype ventilator and two-compartment patient. The microcomputer sampled end-tidal CO2 and calculated a new frequency of ventilation from the difference of end-tidal CO2 and a desired set point value. Use of a microcomputer programmable in BASIC allowed easy manipulation of feedback structure. With the proper choice of feedback constants, the microcomputer was able to maintain end-tidal CO2 at a desired set point.

Carbon Dioxide↗
PubMed1982

Familial juvenile polyposis coli. A clinical and pathologic study of a large kindred.

A kindred with familial juvenile polyposis coli is described. Of 92 family members, 26 have had symptoms consistent with polyposis, and a definite diagnosis of polyposis has been made in 19. Two family members have developed colorectal carcinoma before age 40 yr. The lesion of juvenile polyposis is a characteristic nonneoplastic polyp that is distinct from the neoplastic lesion of adenomatous polyposis. Patients with this disorder develop symptoms at an earlier age than those with adenomatous polyposis. Both variants of polyposis appear to have a dominant pattern of inheritance. Patients with juvenile polyposis who present in infancy are likely to have severe symptoms and complications. Although the premalignant potential of the juvenile polyp remains in doubt, there may be an increase risk of gastrointestinal cancer in these patients and their families.

Adolescent↗
PubMed1982

Unicompartmental arthroplasty of the knee: a review of three-five year follow-up.

Unicompartmental arthroplasty for the treatment of osteoarthritis, that primarily involves a single femorotibial compartment of the knee, has been a controversial procedure. The purpose of this study was to retrospectively review the results of 59 cases in 55 patients, an average of four years after operation. Forty-five of the knees were rated excellent or good and there were eight failures. The thin 6 mm tibial component seemed to be associated with an increased occurrence of loosening and failure of the procedure. There were no failures when thick tibial components were used. The results of this study are encouraging for the use of unicompartmental arthroplasty in the treatment of osteoarthritis of the knee.

Adult↗
PubMed1982

Changes in the flow and composition of gastric lymph in sheep given a primary infection of 10,000 Haemonchus contortus.

Some aspects of the local immune response to a primary infection with 10,000 Haemonchus contortus were studied in five sheep by monitoring changes in the flow and composition of gastric lymph continuously sampled for up to 34 days from the start of infection. Increases in lymph flow rates were recorded in four animals at varying times after the start of infection. These were usually associated with an increase in the protein content of the lymph and were considered to be a consequence of inflammatory reactions in the abomasum. Apart from a small increase in lymphocyte traffic no changes which could be attributed to a local immune responses were observed in the lymph. It is suggested that the chronic nature of infections like haemonchosis is possibly because the worms can parasitise the gut without stimulating a vigorous local immune response.

Albumins↗