Vasectomy increases the severity of diet-induced atherosclerosis in Macaca fascicularis

Long-term effect of vasectomy on coronary heart disease

We investigated the association between coronary heart disease (CHD) and vasectomy in a population of 10,632 men who were under surveillance for multiple CHD risk factors during participation in a university-based exercise testing program. We conducted a mail survey with telephone follow-up to determine the vasectomy status of individuals in the population. Responses were obtained from 6,159 individuals. The 4.944 males on whom information was complete enough to be included in the multivariate analysis comprised the study population. Among the 1,383 (28 per cent) vasectomized males in the study populations, the interval from vasectomy to the time of the survey ranged from less than one year to 37 years with a mean duration of 15 years. Although increased relative risks for CHD were found to be associated with family history of CHD, high blood pressure and smoking in this population, the relative risk of CHD associated with vasectomy was not increased in general, nor was it increased when the vasectomized males were classified by time since vasectomy. Likewise, serum antisperm-antibody titers were not predictive of CHD among vasectomized men. These studies support the findings from previous investigations of populations with shorter average post-vasectomy experience in which vasectomy has been shown to be unassociated with altered risk of CHD in humans.

The effects of vasectomy and exercise on cholesterol levels in rat aortas

The effects of vasectomy and exercise upon esterified, unesterified and total cholesterol in rat aortic tissue was determined. A factorial design with two activity levels (aerobic exercise, sedentary) and three treatments (vasectomy, sham-vasectomy, control) was employed. Vasectomy significantly increased the amount of esterified and total cholesterol in aortic tissue. The vasectomy sedentary group had significantly higher unesterified cholesterol levels than the three exercise groups. Total cholesterol levels were significantly higher for the sedentary groups than the exercise groups. There was no significant difference between exercise and sedentary groups in esterified cholesterol.

Vasectomy and nonfatal myocardial infarction: continued observation indicates no elevation of risk

The incidence of nonfatal myocardial infarction among 4,733 vasectomized men followed for 33,969 man-years was 1.3 cases per 1,000 man-years. This incidence was nearly identical in a 5-fold larger series of comparable nonvasectomized men. These data represent a substantially increased long-term followup over that reported previously for these groups and provide continued assurance of the lack of an association between vasectomy and myocardial infarction, particularly 10 or more years after vasectomy.

Vasectomy and atherosclerosis: an association in man?

We have investigated the distensibility of the lower limb arteries by an ultrasonic technique following vasectomy. Vasectomy accelerates the development of atherosclerosis in animals and this has been attributed to an immunological mechanism. Immunological changes are common in men following this operation, but epidemiological surveys have failed to reveal evidence of an increase in arterial disease. We have studied distensibility at the posterior tibial arteries by Laplace transform analysis of Doppler waveforms in 49 vasectomised men and 33 controls. Statistical analysis of each subject's higher (less distensible) value showed reduced distensibility in the vasectomised group (P = 0.006). This result lends support to the possibility that vasectomy may accelerate the development of peripheral arterial disease in man.

The major histocompatibility complex (CyLA) of the cynomolgus monkey. I. Serologic definition of 21 specificities

Thirty-seven lymphocytotoxic antisera, 27 of which were raised by immunization with skin grafts and blood from partially matched donors, were tested against cells obtained from 218 unrelated animals and 205 offspring from a colony of cynomolgus monkey (Macaca fascicularis). Evidence was obtained for the presence of at least 21 specificities defined by cluster analysis and segregation within families. Allelic relationships between 16 specificities was suggested by segregation patterns, the absence of triplets and statistical analysis of association in the unrelated population sample. The data support a two-locus model, with tentative assignment of seven specificities to the A locus and six to the B locus. That these lymphocyte alloantigens constitute the major histocompatibility complex (MHC) of the cynomolgus monkey is suggested by analogy with other known MHCs and by the increased survival times of skin grafts between paternally matched half sibs compared to haplodistinct full sibs.

Cardiovascular disease and vasectomy. Findings from two epidemiologic studies

We performed two epidemiologic studies using routine abstracts of medical records to test the hypothesis that vasectomy may predispose men to cardiovascular disease. In a case-control study 1512 men who were under 55 years of age and had a history of myocardial infarction, stroke, or hypertension were matched with 3024 controls with other conditions; 2.4 per cent of the cases and 2.7 per cent of the controls were identified as having undergone vasectomy (risk ratio, 0.9; 95 per cent confidence limits, 0.6 to 1.3). In a cohort study data covering a mean period of 6 1/2 years after surgery were available on 1764 men who had had a vasectomy and on three comparison cohorts of men who had had other minor surgical procedures. There was no evidence of an increased risk of cardiovascular disease associated with vasectomy. There is no consistent evidence from our studies to support the hypothesis that in the short term vasectomy predisposes young men to cardiovascular disease.

Vasectomy and the incidence of hospitalized illness

To determine the long-term effects of vasectomy on health we studied the incidence of hospitalized illness in 4,385 vasectomized and 13,155 age and race-matched nonvasectomized men. In none of the 16 disease groupings we examined was the incidence of hospitalized illness in the vasectomized men significantly different from that in the nonvasectomized men, considering men with all durations of vasectomy. Neither the incidence of acute myocardial infarction, other ischemic heart disease nor that of all atherosclerotic diseases considered as a group was significantly different between the vasectomized and nonvasectomized men, even in those whose duration of vasectomy was 10 years or more. These data are reassuring, providing no evidence for an adverse health effect of vasectomy in men.

Effects of long-term immunization against the beta-subunit of ovine luteinizing hormone on circulating immune complex formation and on arterial changes in rhesus monkeys

A major safety issue of contraceptive methods based on long-term immunization is the possible effect of circulating immune complexes (CIC) on the arterial wall. We have measured CIC's in 24 monkeys, immunized against the beta-subunit of ovine luteinizing hormone (oLH beta), emulsified with Freund's complete adjuvant, and in 7 nonimmunized controls by Raji assay, Clq assay, and an assay for rheumatoid factor. Eleven of the 24 immunized monkeys had CIC concentrations that were more than two standard deviations above the mean for controls in at least one of the assays. There was no correlation between antibody titer and CIC. Nine immunized and eight control animals on low-fat diets were killed to evaluate the effects of immunization on the artery wall. The cross-sectional intimal area was measured at several sites from projected microscopic images using a sonic digitizer. No statistically significant differences between test and control groups were found. However, when we compared the upper half of the distribution of test and control animals, we found that the mean intimal area of the thoracic aorta of immunized monkeys was twice that of controls and that that of the abdominal aorta was three times as large. These data indicate that long-term immunization against oLH beta induced CIC's in rhesus monkeys. Small increases in the intimal area were found in about half of the immunized animals. The results of this study suggest the need for a larger, more definitive study in which the diet is manipulated so that plasma lipids mimic those of human females in Western society.

Sperm-agglutinating and -immobilizing antibody formation following vasectomy prevented with dexamethasone in cynomolgus monkeys

Cynomolgus monkeys (Macaca fascicularis) were treated with 1.5 mg/kg dexamethasone (DEX) before (4 to 2 days) and after (0, 2, 4, and 7 days) vasectomy. Of the four monkeys treated with DEX, only one developed sperm antibody as measured by sperm-agglutinating and sperm-immobilizing assays. All six of the vasectomized monkeys not given DEX developed both agglutinating and immobilizing sperm antibodies. In this study, DEX given before and after vasectomy blocked sperm-agglutinating and -immobilizing antibody formation. We conclude that the major antigenic exposure to sperm responsible for sperm-agglutinating and -immobilizing antibody comes at the time of vasectomy.

Sperm-related antigens, antibodies, and circulating immune complexes in sera of recently vasectomized men

Sera from 35 men were collected before and at timed intervals subsequent to vasectomy and examined for the presence of (a) antibody reactive with human spermatozoa, (b) sperm-related antigen, and (c) circulating immune complexes (CIC). Fewer than 10% of the men examined were ever positive for antisperm antibodies. However, sperm-related antigens were elevated in the sera of 18, 18, and 26% of the mean at 2 wk, 2 mo, and 4 mo postvasectomy, respectively. CIC were detected in the sera of some vasectomized men by three different assays. The CIC in patients' sera were precipitated with polyethylene glycol, dissociated, and the individual CIC components identified by an enzyme-linked immunosorbent assay. Most, but not all, of the CIC contained antigen reactive with antisperm immunoglobulin (Ig)G and some also contained complement components C3 and/or Clq. IgA was identified in some of the CIC positive for IgG and sperm antigen and two men had IgM-containing CIC. Analysis of the CIC by sucrose gradient centrifugation revealed them to be heterogeneous in size.

Immunologic aspects of heart disease

All forms of heart disease, whether caused by streptococcus group A, aseptic heart injury, virus, hypersensitivity, autoimmune conditions, or graft-versus-host reactions, have in common allogenic transformation of the myocardial cell membrane and production of multifunctional autoantibodies, in addition to cause-specific antibodies, some of which cross-react with heart tissue. The outcome of this immunologic insult depends on the ability of the host's immunoregulatory mechanisms to dispose swiftly of the offending antigen and antibody or their complexes. Heart disease often results when these mechanisms, exemplified here, are not intact or when they function inappropriately in genetic or acquired settings and in varying haplotype frames.

Germ cell-induced immune suppression in mice. Effect of inoculation of syngeneic spermatozoa on cell-mediated immune responses

Spleen cells from mice injected intravenously with syngeneic male germ cells exhibited reduced immune functions as determined by natural killer cell activity, mixed lymphocyte reactivity and cytotoxic lymphocyte (CTL) function. The decrease in CTL responses to trinitrophenyl-modified self (TNP-self) was detected as early as 4 d after sperm injection and was observed to H-2 alloantigens 3 wk after injection. Radiosensitive suppressor T cells were found to suppress the CTL response to TNP-self. Suppression lasted for a period of at least 7 wk after a single inoculation of the germ cells. Some variability in immune suppression capability was observed using different preparations of germ cells which are not yet completely understood. Sperm were more effective in inducing suppression than testicular cells derived from the seminiferous tubules. Furthermore, sperm from older animals were more effective than those from younger mice. These findings are discussed with respect to possible regulatory influences of germ cells on the immune system when the blood-testes barrier is broken.

A survey of personal habits, symptoms of illness, and histories of disease in man with and without vasectomies

Using questionnaire information provided by 4.385 vasectomized and 13,155 matched, non-vasectomized men, we found no significant differences between them for a large number of symptoms and diseases, including those of the cardiovascular system. After taking into account differences in their martial status, past smoking habits, and physical activity at work, significant statistical associations of vasectomy with joint pain or swelling, back trouble, and a history of kidney or bladder infection persisted. Our data are inconsistent with the occurrence of large increases in the risks of many important diseases in vasectomized humans.

Hypolipidemic effects of gossypol in cynomolgus monkeys (Macaca fascicularis)

The effect of gossypol acetic acid (gossypol) on plasma lipid concentrations was studied in adult male cynomolgus monkeys consuming a diet containing 0.19 mg cholesterol/Kcal. Gossypol was administered orally at 5 (n = 4) or 10 (n = 3) mg/kg/day for 6 months. A significant decrease in total plasma cholesterol (TPC) and low density lipoprotein and very low density lipoprotein-cholesterol (LDL + VLDL-chol) concentrations was observed without any significant decrease in plasma high density lipoprotein-cholesterol (HDL-chol) levels among 10 mg/kg/day gossypol-treated animals. This is a new therapeutic property of gossypol that has been previously reported. No appreciable differences were observed in plasma levels of TPC and LDL + VLDL-chol among 5 mg/kg/day gossypol-treated animals when compared to controls until the gossypol dosage was increased to 10 mg/kg/day, thus suggesting that hypolipidemic effect of gossypol is dose-dependent. In general, no adverse clinicopathological findings were noted except a temporary diarrhea and loss of appetite among 10 mg/kg/day gossypol-treated animals during the initial stages of treatment. In conclusion, it is tempting to speculate that gossypol might possibly reduce the intestinal absorption of dietary cholesterol or it may reduce the hepatic synthesis of low density lipoproteins. These results also suggest that gossypol may be a particularly useful drug in lowering plasma cholesterol concentrations in addition to its previously demonstrated antifertility properties in males.

Immunological control of male fertility

A notable feature of the male gametes is the presence in them of proteins that are "foreign" to the immune system of both male and the female. It is there that are considered responsible for the elicitation of auto- and iso-antibodies in certain natural infertility cases. By virtue of their dual application in both sexes the sperm antigens have interesting potential for exploration as possible agents for control of fertility.

Immunological consequences of vasectomy

In more than 50% of men, vasectomy leads to auto-immune pathology. The auto-immune response to sperms following vasectomy is triggered by the phagocytosis of sperm in the epididymis. In the humoral immune response, sperm agglutinating, sperm immobilizing, and antibodies to sperm nuclear protamines occur, as early as 3-4 days after vasectomy. The incidence reaches 60-70% within 1 year and remains almost the same even after 20 years. Presence and effects of circulating immune complexes following vasectomy are discussed with reference to reported increased incidence of atherosclerosis and auto-immune orchitis in experimental animals. There is no positive conclusion whether vasectomy leads to cell mediated immunity to spermatozoa.

Vasectomy and coronary disease in men less than 50 years old: absence of association

Because recent experiments in primates suggest a relationship between vasectomy, and the development and promotion of atherosclerosis a case control study was performed to explore this possibility in humans. The prevalence of prior vasectomy was determined in 55 men less than 50 years old with onset of documented coronary disease and in a matched control group of close relatives (45 brothers and 10 first cousins) free of coronary disease. The prevalence was the same in each group, 25.5 per cent (14 of 55), and there was no significant difference between study groups in the mean interval since vasectomy. Thus, within the limitations of this study no association of coronary disease with prior vasectomy was found. Further work is needed to evaluate whether the animal findings pertain to humans.

Prevention of autoimmunization to spermatozoa by passive antibody

The objective of this investigation was to determine if sperm antibody formation after vasectomy in guinea pigs can be inhibited by passive administration of antiserum to spermatozoa. Sperm antibody was obtained by bleeding vasectomized guinea pigs which had sperm-agglutinating antibody titers of 1 : 16 or higher. Gamma globulin was obtained by ammonium sulfate precipitation. Vasectomized guinea pigs were injected with immune gamma globulin and normal gamma globulin for a period of two weeks after vasectomy. In the group receiving normal gamma globulin the serum titer of sperm-agglutinating antibody reached 1 : 32 and remained at that level for duration of the study. In guinea pigs receiving immune gamma globulin detectable serum titers of sperm-agglutinating antibody did not develop. The investigation suggests that sperm antibody formation can be prevented by treating vasectomized animals with passive sperm antibody to spermatozoa.

Vasectomy and non-fatal myocardial infarction

The incidence of non-fatal myocardial infarction among 4830 vasectomised men was 0.9 cases per 1000 man-years during 24 420 man-years of observation. This was slightly lower than the rate in 24 150 non-vasectomised men, matched with a vasectomised man for calendar year of birth and duration of observation. Review of medical records for a matched sample of study subjects indicated no measurable confounding by important cardiac risk factors.

Primates: Their use in research on vasectomy

Studies based on experimental vasectomies clearly reveal marked species differences in response to vasectomy. In rats, vasectomy invariably results in granuloma formation at the surgical site. In rabbits, immune-complex orchitis develops. Allergic orchitis may also develop in guinea pigs, and the morphological lesions can be adoptively transferred. My co-workers and I have been able to study systematically, biochemically, hormonally, pathologically, and immunologically, primates vasectomized up to 14 years earlier and to compare them with age-matched controls. We have monitored antibody levels in vasectomized rhesus and cynomolgus macaques by sperm-agglutination, sperm-immobilization, and indirect immunofluorescence techniques. Antibodies develop in almost every monkey, in some as early as 10 days after vasectomy. About 50% retain such circulating antisperm antibodies. In men, antibody development is less rapid, and about half of vasectomized men reveal detectable levels. Testicular histopathological studies have revealed detectable levels. Testicular histopathological studies have revealed orchitis, aspermatogenesis, or both, resembling allergic orchitis in most of the vasectomized monkeys and in about one-fourth of the controls. Limited studies of human material reveal some testicular changes. Epididymitis and epididymal granuloma occur exclusively in the vasectomized animals. Use of immunofluorescence has revealed significantly more granular deposits of IgA, IgG, and/or C3 in the basal lamina of the ductus efferens and the caput epididymidis of the vasectomized monkeys. Similar studies on human material have not been done. Both cynomolgus and rhesus macaques have proved to be excellent models for research in atherosclerosis and so have been used to determine whether constant sperm antigen leakage causes immune-complex formation that might result in arteritis and atherosclerosis. Evaluation of the cardiovascular systems from such animals has revealed that vasectomized monkeys have more frequent, more extensive, and more severe arteriosclerosis than age-matched controls. Epidemiological studies are currently under way to determine whether such an effect also occurs in men after vasectomy.

Atherosclerosis-related responses to cigarette smoking in the baboon

Thirty-six young adult male baboons (Papio cynocephalus) were fed an atherogenic diet (40% calories from lard, 1.5 mg cholesterol/kcal) and taught to puff by operant conditioning with water rewards. Eighteen baboons (smokers) were assigned randomly to smoke 43 cigarettes a day, and 18 baboons (shams) were assigned randomly to puff air under conditions equivalent to those of the experimental group. During months 14-19 of smoking, cigarette-smoking baboons had significantly higher carbon monoxide and thiocyanate concentrations in blood and cotinine concentrations in urine. There were no significant differences in serum total cholesterol, VLDL + LDL cholesterol, HDL cholesterol or triglyceride concentrations of smokers and shams. Smoking baboons had significantly higher fasting blood glucose concentrations and lymphocyte counts. Platelet count, platelet aggregation, food and water intake, and body weight were not significantly different in the two groups.

Vasectomy: five to ten-year follow-up of 200 cases

Five to ten-year follow-up of 200 vasectomies revealed no significant incidence of illnesses or sexual problems.

Long-term vasectomy: effects on the occurrence and extent of atherosclerosis in rhesus monkeys

We demonstrated previously that atherosclerosis develops more extensively in vasectomized cynomolgus macaques fed an atherogenic diet and speculated that the immunologic response to sperm antigens may have exacerbated the atherosclerosis. We report here that rhesus monkeys vasectomized for 9-14 yr and fed monkey chow (devoid of cholesterol and low in fat) rather than an atherogenic diet also had more extensive and severe atherosclerosis than did control animals of the same age. The extent of atherosclerosis was considered as the percentage of intimal surface with plaques. No control animals were found to have plaques in the thoracic aorta, but 7 of 10 vasectomized monkeys were affected. The plaques in the vasectomized monkeys occupied about 13% of the intimal surface. In 4 of 7 control monkeys and 7 of 10 vasectomized monkeys there were lesions in the abdominal aortas; the lesions were considerably more extensive and severe in the vasectomized animals. Lesions were also more common in iliac arteries of vasectomized animals, and the extent was increased about threefold. Plaques were seen at the carotid bifurcation in all of the animals of both the control and vasectomized groups. The carotid bifurcation plaques of the vasectomized monkeys were larger than those of the control animals on the right but not on the left side. Histologically, the lesions of vasectomized monkeys did not appear to be qualitatively different from those of control animals, even though they were larger and contained more collagen, lipid, and mucopolysaccharides. Grossly, the distribution of the lesions in the vasectomized animals was different from that in the control animals, and that of lesions induced by atherogenic diets, i.e., the lesions were distributed randomly within the artery rather than around bifurcations. More extensive atherosclerosis was noted among vasectomized animals that were found to lack demonstrable circulating free antisperm antibodies. On the basis of the observations made in this study, we suggest that the antisperm antibodies that form after vasectomy may result in circulating immune complexes that exacerbate atherosclerosis.

Urologic microsurgery--current perspectives: I. Vasovasostomy

Microsurgical procedures are receiving increased attention in urology, and claims of improved results of vasovasostomy performed with operating microscope have been made. This review examines the available results, sometimes conflicting, of both macro- and microsurgical methods of vasovasostomy. The weight of the data leads to the conclusion that improved results of vasovasostomy will occur with the use of the operating microscope regardless of the type of anastomosis performed because increased appreciation of the detail of the small vasal lumen is afforded by optical magnification.