Effects of Concomitant CABG on Outcomes in Veterans Who Require Surgery for Endocarditis

BACKGROUND

Infective Endocarditis (IE) is a complicated disease frequently accompanied by coronary artery disease (CAD) though no clear guidelines exist for when concomitant revascularization should be undertaken once valve surgery is indicated. Data on this topic within the United States (US) Veteran population, who have unique healthcare needs when compared to the civilian population, is sparse. We investigated the impact of concomitant coronary artery bypass grafting (CABG) on morbidity and mortality in US Veterans requiring surgical management of IE.

METHODS

We identified 489 patients who underwent surgical management of IE between January 1 2010 and December 31 2020 at any of 43 Veterans Affairs (VA) cardiac surgery centers in the US. Patients were stratified based on who underwent concomitant CABG at the time of operation. Primary outcomes included the occurrence of postoperative myocardial infarction (MI), stroke, or mortality. Continuous variables were compared using independent t-tests or Mann Whitney U tests, and categorical variables were compared using the Chi square test. Cox proportional-hazard models were used to calculate risk for primary outcomes based on group.

RESULTS

61 patients (12.5%) underwent concomitant CABG for CAD. After adjusting for significant covariates, patients who underwent CABG had a higher long-term risk of MI (adjusted hazard ratios (aHR) 2.37, 95% CI: 1.29-4.35, p = 0.005) and higher risk of MI at 30-days (aHR 2.34, 95% CI: 1.06-5.19, p = 0.035). Concomitant CABG was not associated with long-term stroke or death, 30-day stroke or death, or perioperative complications. On sub-analysis of patients with moderate to severe CAD, rates of MI were higher in the CABG group at 30 days (25.9 vs. 3.4%, p = 0.016) and 1 year (33.3 vs. 3.4%, p = 0.004), though not long-term. The mean number of grafts was 1.51 ± 0.76, with only one graft performed in 65.6% (40/61) of patients.

CONCLUSIONS

Concomitant CABG at the time of operation for IE was associated with increased risk of MI at 30-day and long-term, though most CABGs involved a low number of grafts. It was not associated with 30-day stroke or death, long term stroke or death, or perioperative complications. The optimal treatment of CAD noted during preoperative evaluation for veterans undergoing surgery for IE remains unclear.

Dorsal Raphe Dopamine Neurons Represent the Experience of Social Isolation

The motivation to seek social contact may arise from either positive or negative emotional states, as social interaction can be rewarding and social isolation can be aversive. While ventral tegmental area (VTA) dopamine (DA) neurons may mediate social reward, a cellular substrate for the negative affective state of loneliness has remained elusive. Here, we identify a functional role for DA neurons in the dorsal raphe nucleus (DRN), in which we observe synaptic changes following acute social isolation. DRN DA neurons show increased activity upon social contact following isolation, revealed by in vivo calcium imaging. Optogenetic activation of DRN DA neurons increases social preference but causes place avoidance. Furthermore, these neurons are necessary for promoting rebound sociability following an acute period of isolation. Finally, the degree to which these neurons modulate behavior is predicted by social rank, together supporting a role for DRN dopamine neurons in mediating a loneliness-like state. PAPERCLIP.

A circuit mechanism for differentiating positive and negative associations

The ability to differentiate stimuli predicting positive or negative outcomes is critical for survival, and perturbations of emotional processing underlie many psychiatric disease states. Synaptic plasticity in the basolateral amygdala complex (BLA) mediates the acquisition of associative memories, both positive and negative. Different populations of BLA neurons may encode fearful or rewarding associations, but the identifying features of these populations and the synaptic mechanisms of differentiating positive and negative emotional valence have remained unknown. Here we show that BLA neurons projecting to the nucleus accumbens (NAc projectors) or the centromedial amygdala (CeM projectors) undergo opposing synaptic changes following fear or reward conditioning. We find that photostimulation of NAc projectors supports positive reinforcement while photostimulation of CeM projectors mediates negative reinforcement. Photoinhibition of CeM projectors impairs fear conditioning and enhances reward conditioning. We characterize these functionally distinct neuronal populations by comparing their electrophysiological, morphological and genetic features. Overall, we provide a mechanistic explanation for the representation of positive and negative associations within the amygdala.

An investigation of the uroselective properties of four novel alpha(1a)-adrenergic receptor subtype-selective antagonists

The development of alpha(1a)-adrenergic receptor (AR) subtype-selective antagonists is likely to result in uroselective agents that effectively treat benign prostatic hyperplasia (BPH) symptoms without causing undesirable side effects that may be due to vascular alpha(1)-AR blockade. The properties of four aryl piperazine compounds (RWJ-38063, RWJ-68141, RWJ-68157, and RWJ-69736) are described in this report and compared with the properties of tamsulosin, an alpha(1)-AR antagonist that is used in the treatment of BPH. Radioligand binding studies show that all four RWJ compounds have significantly higher affinity for the alpha(1a)-AR subtype than for the alpha(1b) or alpha(1d) subtype and display a higher level of receptor subtype selectivity than tamsulosin. The RWJ compounds were more potent in inhibiting (+/-)-norepinephrine-induced contractions of isolated rat prostate tissue than those of isolated rat aorta tissue, whereas tamsulosin had the reversed tissue selectivity. RWJ-38063 and RWJ-69736 had the highest potency in the isolated prostate tissue assays of the four RWJ compounds, with pK(B) values of 8.24 and 9.26, respectively, and were 319- and 100-fold more potent in their effects on isolated prostate tissue than aorta tissue. The in vivo uroselectivities of RWJ-38063, RWJ-69736, and tamsulosin were examined in anesthetized dogs. Both RWJ compounds suppressed the intraurethral pressure response to phenylephrine to a greater extent than the mean arterial pressure response; however, RWJ-69736 also caused a marked transient rise in heart rate. Although less potent, RWJ-38063 and RWJ-69736 were notably more uroselective than tamsulosin in this canine model.

Characterization of ciliary activity in distal Fallopian tube biopsies of women with obstructive tubal infertility

Biopsy specimens were obtained from the distal end of the Fallopian tubes of 62 women with tubal infertility and examined by light and electron microscopy. Ciliary beat frequency (CBF) measurements were obtained using laser light spectroscopy. Neither demographic nor behavioural characteristics nor serological evidence of past chlamydial infection were associated with CBF measurements. In contrast, CBF were significantly lower (P < 0.05) in tissues with oedema compared to tissues without oedema (6.7 versus 12.9) and in tissues with erythema compared to tissues without erythema (9.2 versus 13.7). Furthermore, CBF measurements did vary by chlamydial serotype pattern, with lower values observed among the tissues of women with antibodies to serotype C or E (without D) as compared to the tissues of women with other serotypes (P < 0.04). However, these data must be interpreted with caution as the numbers of subjects with chlamydial antibodies to serotype C (n = 3) or E without D (n = 5) were few in number and serotyping of IgG antibodies in blood is not as accurate as it is in bacterial isolates. Confirmation of the suggested association between chlamydial serotype and risk of adverse sequelae could indicate potential new avenues for vaccine research.

Function and structure of cilia in the fallopian tube of an infertile woman with Kartagener's syndrome

In Kartagener's syndrome (KS), primary defects of the ciliary axoneme cause dyskinetic ciliary motion. Because ciliary motion is an important factor in normal ovum transport, ciliary dyskinesia may cause infertility. On the other hand, the existence of some ciliary activity, albeit abnormal, may account for fertility in some women with KS. In this case study, an infertile woman diagnosed with KS had normal results in all usual infertility tests. Biopsies of tubal mucosa were obtained at laparoscopy for ovum recovery during an in-vitro fertilization cycle. Ciliary activity, measured by laser light-scattering spectroscopy, was detected in all tubal specimens; however the majority of regions sampled showed no activity. In active regions, beat frequency ranged from 5 to 10 Hz, approximately 30% of normal. Electron microscopy showed similar morphological defects in both tubal and nasal mucosa. The number of cilia per cell was approximately 20% of normal. The major ultrastructural abnormality of cilia was an absence of the central microtubules. The only demonstrable explanation for this patient's infertility was primary ciliary dyskinesia associated with KS.

Intravascular monitoring: problems and promise

Intravascular monitoring of arterial blood gases provides the means to detect precipitous change in cardiopulmonary function almost instantaneously, promising major improvement in the ability to manage critically ill patients. Attempts to miniaturize and repackage conventional electrodes for continuous intravascular use have met insurmountable problems, and only the application of new technology involving fiber-optic chemical sensors (FOCS) has proved that in vivo monitoring of blood gas chemistry is truly feasible. Although a wide range of analytes of clinical significance may potentially be monitored by using FOCS technology, the analytes of choice for the management of the critically ill patient are pHa, paCO2, and paO2, because of their dynamic nature and importance for critical-care diagnosis and monitoring. Although intravascular FOCS blood gas monitors currently under clinical investigation exhibit promising performance, clinical acceptance and commercial success will depend on the creative solution of several problems, the most challenging of which are related to physiological factors at the interface between the sensors and their intravascular sensing environment.

Intravascular monitoring: problems and promise

Intravascular monitoring of arterial blood gases provides the means to detect precipitous change in cardiopulmonary function almost instantaneously, promising major improvement in the ability to manage critically ill patients. Attempts to miniaturize and repackage conventional electrodes for continuous intravascular use have met insurmountable problems, and only the application of new technology involving fiber-optic chemical sensors (FOCS) has proved that in vivo monitoring of blood gas chemistry is truly feasible. Although a wide range of analytes of clinical significance may potentially be monitored by using FOCS technology, the analytes of choice for the management of the critically ill patient are pHa, paCO2, and paO2, because of their dynamic nature and importance for critical-care diagnosis and monitoring. Although intravascular FOCS blood gas monitors currently under clinical investigation exhibit promising performance, clinical acceptance and commercial success will depend on the creative solution of several problems, the most challenging of which are related to physiological factors at the interface between the sensors and their intravascular sensing environment.

Ovum transport in the rat oviductal ampulla in the absence of muscle contractility

Ovum transport in mammalian oviducts involves two main effectors: ciliary motility and muscle contractility. To study the relative contribution of cilia to ovum transport in the rat, we blocked smooth muscle activity with isoproterenol, a beta-adrenergic agonist, and measured transport rates of surrogate ova in situ. Transport rates before isoproterenol administration were 0.04 mm/s in the cephalic ampulla and 0.03 mm/s in the caudal ampulla; rates were unchanged after administration of isoproterenol. To determine if isoproterenol affected ciliary activity, we measured ciliary beat frequency with laser-scattering spectroscopy over the effective isoproterenol dosage. Isoproterenol did not cause a significant change in ciliary beat frequency. Our results show that in the rat oviductal ampulla, ciliary motion is capable of transporting ova in the absence of muscle contractility.

A comparison of the fallopian tube's response to overt and silent salpingitis

We examined two groups of infertile women who underwent microsurgical repair of their fallopian tube(s) for distal tubal obstruction, one with a history of salpingitis (overt pelvic inflammatory disease) (N = 34) and one without (silent pelvic inflammatory disease) (N = 25). Nine women with normal tubes undergoing hysterectomy and salpingectomy served as controls. Tubal biopsy specimens were studied by light, scanning, and transmission electron microscopy to assess tubal damage. Morphologic damage was scored 0-9, with 0 representing normal tubal architecture and 9 assigned to severe tubal damage. The mean score (+/- SEM) in women with overt pelvic inflammatory disease was 4.2 +/- 0.4; in women with silent pelvic inflammatory disease, 4.3 +/- 0.4; and in the control group, 0.76 +/- 0.2 (P less than .001). Fallopian tube abnormalities seen in women with overt and silent pelvic inflammatory disease included flattened mucosal folds, extensive deciliation, and degeneration of secretory epithelial cells, morphologic changes that are similar to the cellular changes observed in our experimental Chlamydia trachomatis infections in monkeys. Laser light-scattering spectroscopy was used to measure the ciliary activity of the epithelial cells. Ciliary beat frequency was significantly reduced in women with overt pelvic inflammatory disease (N = 13; f = 6.4 +/- 1.2 Hz) and in women with silent pelvic inflammatory disease (N = 11; f = 7.2 +/- 1.2 Hz) as compared with the controls (N = 5; f = 23.4 +/- 1.5 Hz) (P less than .001).(ABSTRACT TRUNCATED AT 250 WORDS)

Anatomical basis of a passive mechanism for ovum retention at the ampulloisthmic junction

The unexplained behavior of egg retention at the ampulloisthmic junction (AIJ) is a mechanical phenomenon; therefore the key to this process must lie in the anatomy of the oviduct. To investigate the concept that simple anatomical differences between ampulla and isthmus cause AIJ retention, we quantified, in these two regions of the rabbit oviduct, the structural characteristics of the tubal wall that show marked differences: wall thickness and luminal caliber. The oviductal wall greatly increases in thickness and decreases in luminal caliber abruptly at the transition from ampulla to isthmus. These passive mechanical factors predict a dramatically reduced distensibility of the isthmic wall compared to that of the ampulla, and these factors provide us with a simple model to account for the apparent sphincteric activity of the AIJ. Actual measurements of tubal distensibility confirmed our prediction. In addition, egg transport studies following microsurgical removal of the AIJ showed normal transport, an indication that no special structure need exist at the AIJ. We conclude that the contrasting morphology of the ampulla and isthmus may suffice to explain AIJ retention, and no special active mechanism need be postulated.

Distribution of embryos and 500-microM microspheres in the rabbit oviduct: controls for acute motion analysis during transport

Distributions of embryos and 500-micron diameter microspheres were measured in the cleared oviducts of 32 rabbits at 8 intervals post coitus (pc) and normalized to percentage of isthmic length. By 18 h pc, 46% of the embryos had entered the isthmus and were denuded of the cumulus, while 55% of the microspheres had entered the isthmus. By 24 h pc, all embryos and microspheres were in the isthmus. At 72, 78, and 84 h pc, 6.5, 37, and 93% of embryos and 21, 73, and 95% of microspheres were in the cornu, respectively. The mean positions of embryos and microspheres progressed at approximately 1% of isthmic length per hour between 24 and 72 h pc. Throughout isthmic transport, embryos and microspheres in individual oviducts were tightly grouped and had similar statistical distributions. Although microspheres began to transfer into the uterine horns earlier than embryos, the data suggest that 500-micron microspheres can be used in studies to quantify discrete movements within the oviduct prior to 72 h pc. The data further suggest that opposing forces may be generated by contractile events that keep embryos grouped and possibly control their rate of progress through the oviduct.

Distal tubal obstruction induced by repeated Chlamydia trachomatis salpingeal infections in pig-tailed macaques

The effects of repeated infections with Chlamydia trachomatis, serovars F, D, and J, were examined in pig-tailed macaques. The fallopian tubes of three experimental monkeys were inoculated at the middle of the menstrual cycle on three consecutive months. Monkey 1 received homologous F; monkey 2 received heterologous F, D, and J; and monkey 3 received homologous inoculations in the right and heterologous inoculations in the left fallopian tubes. One control monkey (4) received repeated inoculations of HeLa cell materials only and remained normal throughout the experiment. Infection was confirmed by isolating the microorganism from both the endosalpinx and endocervix. Antibody to the infecting strains was demonstrated in sera, tears, and cervical secretions by using microimmunofluorescence. Mild chronic salpingitis developed in monkeys 1 and 3, and chronic follicular salpingitis developed in monkey 2. Peritubal and periadnexal scarring and endosalpingeal adhesion formation were produced after reinfection. The right fallopian tube of monkey 3 was distally obstructed (confirmed by hysterosalpingography). Systemic complications, including perihepatitis and conjunctivitis, were also documented in these monkeys. We conclude that repeated infections produced extensive tubal scarring, chronic salpingitis, and distal tubal obstruction, findings not apparent in primary infection.

A comparison between argon laser and microsuture anastomosis of the rat uterine horn

For assessment of the use of the argon laser for tubal anastomosis, the uterine horns of 12 Sprague-Dawley rats were surgically divided and then anastomosed, 6 by argon laser photocoagulation and 6 by the conventional technique of microsurgery. After a 4- to 6-week postsurgical period subjects were reexamined. All microsutured anastomoses were fully patent and continuous, with no apparent fibrosis. Four of six laser subjects had complete occlusion; the other two exhibited patencies between 10% and 20% of normal luminal area. Although initially producing satisfactory union, argon laser photocoagulation proved highly tissue traumatic, resulting in poor regeneration of the anastomotic site.

Induced hydrosalpinges in rabbits: comparison of hysterosalpingographic media and development of an animal model

Experiments were conducted in rabbits to test the effect of commonly used hysterosalpingographic media on tubal structure and function. A model of hydrosalpinx was created by ligating both ends of the oviduct, and the lumen was filled with test solutions. Three groups of animals were studied. Group 1 rabbits (operated controls) received Hanks' balanced salt solution or no solution. In the second group (unoperated controls), no solution or occlusive ligature was applied. Group 3 received either Ethiodol (Savage Laboratories, Missouri City, TX), an oil-soluble contrast medium (OSCM), or Sinografin (E.R. Squibb & Sons, Princeton, NJ), a water-soluble contrast medium (WSCM). Histopathologic changes in the endosalpinx were moderate in the doubly ligated oviducts, and no difference was found between the effects of OSCM and WSCM in group 3 or between groups 1 and 3. Ciliary transport rate on the ampullary endosalpinx of group 1 was 0.05 mm/second, i.e., half the normal rate in the unoperated controls (P less than 0.001) and OSCM-filled oviducts (P less than 0.01). The rate in WSCM oviducts was 0.01 mm/second, significantly slower than in the OSCM-filled oviducts (P less than 0.05).

Quantification of intraluminal motion of surrogate ova in the rabbit oviductal isthmus

The feasibility of using black polystyrene microspheres as surrogate ova to obtain quantitative information regarding ovum motion in the oviductal isthmus was tested in rabbits. The 175-microns diameter surrogates were instilled into the ampulla at the time of ovulation, and later the oviducts were exposed for direct observation of surrogate movements in the isthmic lumen. With the aid of transillumination, the black spheres were visible through the intact tubal wall and cinematographic records were made to quantify their movements. The frequency of surrogate movements was 5/min at 24, 36 and 48 h after coitus an 10/min at 60 and 72 h. The motion was typically oscillative with individual movements less than 4 mm in length; usually no net displacement occurred during 1-2 h of observation. These preliminary data, when used to test the stochastic model of ovum transport proposed by Verdugo et al. (1980), predicted isthmic transit times of only a few hours. Thus, the long duration of ovum residence in the rabbit isthmus may not be due to a slow transport process governed by random motion.

Host response to primary Chlamydia trachomatis infection of the fallopian tube in pig-tailed monkeys

Experimental acute salpingitis was produced in four pig-tailed monkeys, Macaca nemestrina, by intratubal inoculation with Chlamydia trachomatis (serotypes E or F). The organisms were reisolated from both the endosalpinx and endocervix as early as 1 week after the original inoculation. Endosalpinx cellular responses to the infection were examined by light, transmission, and scanning electron microscopy. A moderate lymphocyte infiltration was detected in the submucosa on day 7. By days 14 and 21 the lymphocytic infiltration was heavy and extended into both the submucosa and the mucosa; the infiltration subsided by day 35. Epithelial cell degeneration occurred in close approximation to lymphocytes, suggesting the immunologic basis of tissue destruction. Scanning electron microscopy revealed extensive deciliation and increased plasmalemmal alterations of nonciliated cells. The presence of C. trachomatis in frozen and deparaffinized tissues was demonstrated by immunofluorescence and immunoperoxidase staining with monoclonal antibody to C. trachomatis. Only secretory cells contained chlamydial inclusions. A humoral immune response to C. trachomatis was demonstrated by microimmunofluorescence. No histologic or immunologic evidence of infection was present in two control monkeys inoculated with HeLa cell material. The histopathologic and immunologic findings of this study establish the pig-tailed monkey as a useful model for further studies of the pathogenesis and pathophysiology of chlamydial salpingitis.

Experimental salpingitis in rabbits provoked by Chlamydia trachomatis

Experimental salpingitis was studied by the introduction of Chlamydia trachomatis, immunotype D, directly into the oviducts of New Zealand White rabbits. Some rabbits were rechallenged with immunotype F to elicit a second infection. Both experiments produced self-limited acute salpingitis. Light microscopy (LM) and transmission electron microscopy (TEM) showed an extensive polymorphonuclear leukocytic infiltration in the submucosa and mucosa. Scanning electron microscopy (SEM) revealed various alterations of the endosalpingeal surface, including deciliation and flattening of the epithelial cells. These morphologic changes were more pronounced following rechallenge. High and long-lasting serum antibody titers were observed in those rabbits receiving intratubal inoculation of live infectious organisms; no response was evident when inactivated organisms were used. These results indicate that the rabbit is useful in the study of the effects of infection on oviductal function.

Mechanically-induced hydrosalpinx: long-term oviductal dilatation does not impair ciliary transport function

Long-term hydrosalpinges were mechanically induced in rabbits by ligation of the fimbriated end of the oviduct. The structure and function of these model hydrosalpinges were studied 28 to 52 weeks following ligation. This procedure caused a nonpurulent, clear serous fluid to accumulate within the lumen of the ampulla, which resulted in dilatation of the ampulla and thinning of the tubal wall. The intraluminal mucosal folds were attenuated in the expanded regions; however, normal ciliation was predominant throughout the endosalpinx. Two rabbits, one with a single distal tubal ligation and the other with double ampullary ligation, showed abnormal epithelium with distinct patches of flattened polygon-shaped, nonciliated cells. In vivo and in vitro observations of luminal transport of surrogate ova in cumulus showed that ciliary transport was not affected by the long-term gross distension of the ampullae. The authors conclude that long-term tubal dilatation by itself does not alter tubal morphology sufficiently to impair ovum transport function in the oviductal ampulla.

Reproduction in rabbits after excision of the oviductal isthmus, ampullary-isthmic junction, and uteroisthmic junction

The effect of total deletion of the isthmus, including the ampullary-isthmic junction and the uteroisthmic junction, upon reproduction was determined in 21 rabbits. None became pregnant on the side lacking isthmus, whereas all became pregnant on the intact control side. Eight does were studied using in vivo and in vitro techniques at 18 to 20, 64 to 65, and 136 to 137 hours after mating. Spermatozoa fertilized the ova, with evidence of polyspermy. However, the modified oviduct did not transport fertilized ova into the uterus at the normal time. Furthermore, degeneration was noted from the morula stage onwards. We conclude that the rabbit ova can neither develop normally past the morula stage nor enter the uterus at the normal time in a recognizable form in the total absence of isthmus, and infertility results.

The structural and functional impact of microsurgical anastomosis on the rabbit oviductal isthmus

Microsurgical transection and anastomosis of the left isthmus in 7 rabbits caused fertility to be reduced 40%. Following rebreeding artificial eggs were introduced into the anastomosed and control oviducts. Sixty-three to 65 hours after mating, direct in vivo observations disclosed varied forms of motion of the artificial eggs within the isthmus, including both small oscillations and occasionally, large precipitous excursions covering more than 1 cm. Subsequent clearing of the genital tracts revealed that the anastomosis in the isthmus had detained most of the natural and artificial eggs, whereas both forms of ova were predominantly past the equivalent site on the control side; yet all anastomosed oviducts were fully patent. We conclude that the decreased fertility after isthmic anastomosis is due not to a physical obstacle but to an inability of the isthmus near the anastomosis to dilate as do other regions of the tube.

The effect of autonomic drugs on ureteric peristalsis: a canine in vivo study

An in vivo canine model was developed in which the renal pelvis was perfused by a cannula nephrostomy and ureteric activity assessed by monitoring bolus volume and interperistaltic interval. The effect of autonomic drugs showed that the ureter contained alpha-adrenergic receptors which on stimulation caused an increase in ureteric contraction rate and a decrease in bolus volume. With beta-adrenergic receptor stimulation, there was complete inhibition of ureteric peristalsis for a variable period and evidence is presented that the beta-adrenergic receptors may be beta 1 rather than beta 2. Cholinergic stimulation of ureteric rate was observed, but seemed to be mediated indirectly via alpha-adrenergic receptors. No significant change was seen in ureteric activity with adrenergic blocking agents alone, suggesting that the physiological importance of these receptors in normal activity is questionable.

Function and structure of the rabbit oviduct following fimbriectomy. II. Proximal ampullary salpingostomy

Experiments were conducted in nine New Zealand White rabbits to determine the functional capacity of that part of the oviduct consisting of only the isthmus and proximal ampulla. The left fimbria and at least one-half of the adjoining ampulla were excised microsurgically and the remaining portion of the proximal ampulla was subjected to a cuff salpingostomy. Following a convalescence of 4 to 8 weeks and gonadotropin-induced ovulation, direct observations in vivo showed tht the modified oviduct was ineffective in transporting surrogate cumulus masses into the tubal lumen. Those surrogates that were accepted were in some cases regurgitated by contractions of the residual proximal ampulla. A subsequent in vitro search for ova proved that the modified oviducts were unsuccessful in retrieving ipsilaterally ovulated ova, whereas the contralateral control oviducts apprehended an average of 72% of those available. Scanning electron microscopy showed the everted mucosa of the proximal ampulla to be less richly endowed with cilia than that of the normal fimbria. This ovum capture appeared to be prevented by deficiencies in both the ciliary mechanism of the neofimbria and the ability of the remaining ampulla to retain the egg. This evidence indicates that the proximal ampulla is unsuitable for reconstruction of a functional fallopian tube.

Function and structure of the rabbit oviduct following fimbriectomy. I. Distal ampullary salpingostomy

The fimbria has long been considered an indispensable portion of the fallopian tube. To test this hypothesis, the fimbria and up to one-half of the adjoining ampulla of the left oviduct were resected by microsurgery in 13 New Zealand White does. The remaining distal ampulla was subjected to a cuff salpingostomy. Following a convalescence of 4 to 8 weeks and induced ovulation, 6 of the 11 resected oviducts apprehended ova and 29% of the total number ovulated ipsilaterally, whereas the right control oviducts retrieved 77% of the corresponding ova. Direct observation in vivo showed that the ova adhered to the neofimbria and that subsequent transport across the everted, hypertrophied ampullary mucosal folds into the tubal lumen took place readily. Scanning electron microscopy of the "neofimbria" and adjoining distal ampulla demonstrated populations of ciliated and secretory cells that were similar to those of the contralateral intact fimbria. This information challenges the concept of fimbrial indispensability and depicts the fimbriated ostium of a distal ampullary cuff salpingostomy as having an adequate function, albeit less efficient than normal

Hydrosalpinx: effect of oviductal dilatation on egg transport

Ligation of the ovarian end of the oviduct was used to induce hydrosalpinges in rabbits and monkeys. This procedure resulted in an accumulation of clear serous fluid within the lumen and distention of the ampullary wall. The ampullary endosalpinx responded with a general flattening of the surface architecture, especially a decrease in the prominence of the longitudinal mucosal folds. However, this flattened epithelial surface showed normal ciliation. Two to five months after ligation, direct observations were made in vivo of luminal transport of cumulus egg masses and surrogates. These observations were followed by study in vitro of ciliary currents on the exposed luminal surface. The results demonstrated conclusively that tubal dilatation had no adverse effect on cilia-mediated ovum transport within the ampulla. The implication of these results in terms of tubal infertility is discussed.

The effect of glucagon and diazoxide on the normal and obstructed upper urinary tract

The effect of diazoxide and glucagon were studied on the freely draining upper urinary tract and after varying periods of obstruction in dogs. Without obstruction, diazoxide produced longer inactive periods than glucagon and recovery was associated with less retrograde activity. Following obstruction for 5--10 min, 6 and 24 h, diazoxide decreased renal pressure and the effect was greatest when the upper tract was obstructed for the shortest period. Glucagon also produced an overall reduction in pressure after 5--10 min and 6-hour periods of obstruction, but there was an initial rise in pressure after 5--10 min of obstruction. At 24 h there was an increase, but no overall decrease in pressure after glucagon. Diazoxide produced a greater fall in pressure after 5--10 min and 24 h of obstruction, and a faster fall in pressure after 5--10 min and 6 h of obstruction as compared to glucagon. Diazoxide may be a more effective therapeutic agent in the management of ureteral calculus disease than glucagon.

Pregnancy, ciliary transport, and the reversed ampullary segment of the rabbit fallopian tube

Pregnancy following reversal of an ampullary segment in the rabbit oviduct has occurred only sporadically, and then usually after repeated mating. To explain this phenomenon it has been postulated that the direction of ciliary beat in the reversed ampullary segment must revert to the normal pro-uterine direction. To test this hypothesis a segment of the ampulla was reversed by microsurgery in 10 rabbits. These were then bred repeatedly for as long as 28 weeks. A single pregnancy, at 10 weeks, ensued. Observation of ampullary transport in vivo showed that muscular activity in the reversed ampullary segment may occasionally overcome the adverse, pro-ovarian ciliary currents that were found to persist in subsequent in vitro examinations. Scanning electron microscopy confirmed normal ciliation in the reversed segment. These observations may explain the occasional transport of an ovum across the reversed ampullary segment and an isolated pregnancy in the mated rabbit.

In vivo recording of oviductal contractions in rabbits during the periovulatory period

Muscular activity of the oviductal isthmus was recorded in intact awake rabbits with an extraluminal optoelectronic transducer. Telemetered data were collected continuously during the periovulatory period to relate changes in contraction frequency to oviductal transport function. Mean frequencies during estrus ranged from 11.7 to 18.7 contractions/min. Animals stimulated to ovulate either by luteinizing hormone (LH) or by mating showed equivalent responses. Within 2 h following the stimulus, the frequency increased rapidly and remained elevated more than 50% above the estrous control level for approximately 10 h. Thereafter, the frequency declined slowly to reach a second plateau, 30% below the control level, which was maintained throughout the 2nd and 3rd poststimulus days. Subsequently, the activity returned to the prestimulus level. The periods of elevated and depressed activity correspond closely in time to the periods of rapid preovulatory transport of sperm and slow postovulatory transport of ova through the isthmus, suggesting the possibility of regulation of gamete transport by the oviductal musculature.

Optoelectronic transducer for in vivo recording of oviductal contractile activity

An optoelectronic instrument to record oviductal muscular activity in chronically instrumented animals was evaluated in in vitro and in vivo experiments. The intensity of red light transmitted through the oviduct was modulated by contractions of the oviductal wall producing an optical analog of the mechanical events. Accuracy of the analog was tested by Fourier analysis of signals from mechanical and optoelectronic transducers placed at the same site on the oviduct; the results validated the use of the optical device as a contraction event sensor. Contractions of the tubal mesenteries had less effect on the optical signal than on signals from extraluminal mechanical transducers. Optical and photographic recordings of luminal transport in exposed oviducts showed a correspondence of intraluminal movements to events in the optical contraction signal. This instrument does not alter tubal function, and thus it is an especially useful experimental tool to investigate the role of oviductal muscular activity in fertility.

A stochastic model for oviductal egg transport

A mathematical description of ovum transport based on Langevin's diffusion equation is presented. The proposed model is deduced from qualitative features of this phenomenon, not induced from numerical fitting of experimental data. We demonstrate that egg transport in the ampulla of the rabbit oviduct can be represented as a one-dimensional random walk in a field of external force. The application of the model to describe isthmic ovum and sperm transport on the basis of simple random walk process is also discussed. The present formulation identifies and characterizes the forces involved in the motions of the ovum and predicts specific alternatives for physiological regulation of egg transport in the oviduct.

Egg transport in the rabbit oviduct following ampullary resection and microsurgical end-to-end anastomosis

Surgical alteration of rabbit oviducts was employed to investigate the mechanisms of ovum transport. Resection of a 5- to 10-mm segment of midampulla was followed by microsurgical end-to-end anastomosis. One to two months later, direct observations were made, in situ, of ampullary egg transport. Stained cumulus masses were transported normally to the site of anastomosis: two-thirds of those studied were delayed at that point for an average of 2 1/2 minutes. Normal transport then resumed and continued to the ampullo-isthmic junction. In all but one instance, blockage of muscular activity with isoproterenol prevented transport beyond the anastomosis site, demonstrating the presence of an obstacle to ciliary transport. These studies reveal an important facilitative role for muscle in improving the reliability of ampullary egg transport. Considering species differences in egg transport mechanisms, it is suggested that ampullary-ampullary anastomosis in women might have a poor prognosis for re-establishing fertility.

Eelectron microscopic examination of the rabbit oviductal ampulla following microsurgical end-to-end anastomosis

The endosalpinx of both normal and microsurgically reconstructed ampullae in rabbit oviducts was examined by scanning and transmission electron microscopy following ovum transport studies. Tall, longitudinal mucusal folds ran continuously throughout the lumina of normal ampullae and were clearly interrupted at the incision site in the reconstructed oviducts. In both normal and surgically repaired tubes the endosalpinx was covered with long, slender cilia and bulbous processes of secretory cells with microvillous surfaces. Intracellular examination of these epithelial cells suggested no abnormal structure or function. These observations indicate that the epithelium on the severed ends of the endosalpinx healed completely within 1 month following ampullary anastomosis. Since no luminal obstruction was observed, the interruption and misalignment of the mucosal folds appear to be the cause of the impaired ciliary transport of cumulus masses observed in these oviducts. When species differences in tubal structure and function are considered, it appears likely that ampullary-ampullary anastomosis could hinder egg transport and fertility in women.

Polycationic macromolecules inhibit cilia-mediated ovum transport in the rabbit oviduct

In both in vitro and in vivo experiments, polycationic macromolecules,such as poly(L-lysine), inhibited the transport of either surrogate or freshly ovulated cumulus masses across the oviduct epithelial surface without affecting the ciliary beat. Whereas transport across the fimbria in vivo was completely inhibited, transport down the ampulla was 3 to 7 times slower than normal. The effects of these polycations suggest that cilia-mediated ovum transport may involve the formation of transient adhesive bonds between the tip of the cilium and elements of the cumulus mass during each beat cycle of the cilium.

Egg transport in the rabbit oviduct: the roles of cilia and muscle

Ciliary ovum transport through the oviductal ampulla was investigated, in vivo, by blocking smooth muscle activity. Isoproterenol eliminated rapid muscle-induced egg movements, yet the egg and its surrounding cells reached the site of fertilization within normal time limits. The role of cilia in ovum transport thus seems more important than that of the smooth muscle.

An analysis of the mechanisms of egg transport in the ampulla of the rabbit oviduct

Ampullary transport of supravitally stained cumulus egg masses was studied in intact oviducts of anesthetized rabbits whose abdomens had been opened for observation. Following observations of normal transport, muscular activity of the ampulla was inhibited pharmacologically with Acepromazine, a preanesthetic tranquilizer. With muscle contractions blocked, egg transport continued but in a dramatically altered fashion; in the final two thirds of the ampulla the motion changed from rapid to-and-fro movements to a slow uniform prouterine movement which was attributed to ciliary activity. However, the net velocity of transport did not change when the smooth muscle was inhibited indicating that muscle contractions are at least unnecessary and perhaps ineffective for ampullary egg transport in the rabbit.

In vitro contractile activity of the mesotubarium superius from the rabbit oviduct in various endocrine states

We investigated the influence of estrogen on the contractile activity of smooth muscle in the nonpregnant female reproductive tract, using as a model isolated strips of mesotubarium superius (MTS) removed from the rabbit oviduct. We studied four physiologic states in which muscular activity was influenced to varying degrees by endogenous estrogen. Normal estrous (estrogen dominated) rabbits were used as controls. We observed decreased activity in MTS from rabbits chronically deprived of estrogen (60) days postovariectomy). However, a dramatic increase in activity occurred in response to acute withdrawal of ovarian function (12 hours postovariectomy). An increase in activity also occurred at the time of ovulation. We concluded that acute withdrawal of endogenous estrogen is a potent stimulus to reproductive smooth muscle in the female rabbit and that it might contribute to increased muscular activity at ovulation.