Permanent cardiac pacing and thromboembolic risk in elderly patients

In patients undergoing permanent cardiac pacing, the maintenance of atrial contractility is important to ensure adequate ventricular filling and to guarantee an optimal ventricular ejection capacity. The appropriate pacing mode, assuring a suitable mechanical atrioventricular coupling, prevents the onset of atrial fibrillation and contributes to reduction of the risk of subsequent systemic and pulmonary thromboembolic episodes. We examined 461 patients (266 males and 195 females, aged between 52 and 97 years, average age 76.5 +/- 18) paced for conduction disturbances of various degrees and etiology. Of them, 323 patients received ventricular demand pacemaker (VVI group, average age 77.9 years); 138 underwent dual chamber pacing (DCP group, average age 75.2 years), 117 of the latter received universal demand pacing (DDD) and 21 atrial synchronous ventricular demand pacing (VDD). The patients were subsequently divided into two age-groups: Group A (</= 75 years, 174 patients), and Group B (>/= 75 years, 287 patients). According to pacing mode and successive development of stable atrial fibrillation (AF), we analysed the occurrence of systemic and/or pulmonary thromboembolic episodes and the incidence of fatal events. During our study, performed from January 1986 to August 1993, 70 embolic episodes were observed in the VVI group and six in the DCP group. Eighty-four patients with VVI units developed AF during follow-up, compared with only five patients in the DCP group. Our data indicate that VVI patients have a higher incidence of AF, embolic complications and cerebrovascular mortality, in comparison with the DCP group. VVI pacing should be avoided, especially in older patients, when atrial rhythmical activity is present.

[Magnetic resonance and traditional radiology in the spine localizations of alkaptonuric ochronotic arthropathy]

AIM

To study the spine alterations in alcaptonuria with traditional radiology and magnetic resonance (MR), comparing the results of the two techniques.

PATIENTS AND METHODS

Five patients (4 males, 1 female, mean age 51 years) underwent the examinations. For the study with X-rays we performed anteroposterior and lateral scan and the images have been studied making reference to a radiographic score; it examines the alterations of the joint space and the presence of calcifications. MR scan, oriented in the three spatial planes, were performed using spin echo T1-weighted and spin echo T2-weighted sequences.

RESULTS

Both MR and X-rays pointed out, in the cases with known diagnosis, the typical alterations of the ochronosis: narrowing of the articular spaces, even osseous ankylosis, calcifications of the discs, osteophytosis, multiple disc protrusions and reactive sclerosis of the articular surfaces, evident above all to dorso-lumbar tract; nevertheless MR has been more accurate than X-rays for individualizing the lesions and recognizing alterations, such as the thickness of the anterior longitudinal ligament. In the case of new diagnosis, the MR is fundamental to recognize typical signs of the ochronotic arthropathy not well detected by X-rays.

CONCLUSIONS

Imaging techniques, first of all the MR, are essential in the differential diagnosis of ochronosis vertebral lesions with other articular diseases.

Identification, localization and functional in vitro and in vivo activity of oxytocin receptor in the rat penis

We recently found that the oxytocin receptor (OTR) is expressed in the human and rabbit corpus cavernosum and mediates contractility in vitro. The present study extended our investigations to the rat, and explored whether OTR regulates penile detumescence in vivo. Real-time RT-PCR quantitatively characterized the distribution of OTR mRNA in the male genital tract. Specific transcripts for OTR were expressed in all the tissues investigated. Penile expression of OTR was comparable to that observed in testis and prostate. Western blot analysis detected a single band of the expected molecular mass for OTR in all tissues examined, including rat penis. Expression of OTR protein in rat penile extracts was further confirmed by binding studies, using the OTR selective radiolabeled ligand 125I-OTA (K(d) = 17 +/- 6.5 pM, B(max)=15.7 +/- 5 fmoles/mg protein). OTR was immunolocalized to the endothelial and smooth muscle compartments of cavernous spaces and blood vessels. In rat corpus cavernosum strips, oxytocin (OT) and an OTR selective agonist ([Thr4,Gly7]OT) induced identical increases in tension, while different vasopressin agonists were less active. In vivo, OT intra-cavernous injection (ICI) dose-dependently inhibited intracavernous pressure (ICP) increase elicited by either electrical stimulation of the cavernous nerve or ICI of papaverine with similar IC(50)s (117.7 +/- 37 mU). The OTR antagonist, atosiban, counteracted the contractile effect of OT both in vitro and in vivo. Atosiban alone significantly increased ICP at lower stimulation frequencies (2 Hz = P<0.001 and 4 Hz = P<0.05 vs control), but not at the maximal frequency (16 Hz). Our data showed that OTR is present in the rat penis and mediates contractility both in vitro and in vivo, therefore suggesting a role for OT in maintaining penile detumescence.

Expression and functional activity of phosphodiesterase type 5 in human and rabbit vas deferens

The molecular mechanisms underlying the regulation of vas deferens (VD) motility and semen emission are still poorly understood. We now report evidence on VD expression of phosphodiesterase type 5 (PDE5), which regulates nitric oxide (NO)-induced relaxation and cGMP breakdown in smooth muscle cells. In human VD, the PDE5 abundance was relatively high (>3 x 10(6) molecules/microg total RNA), although 10-fold lower than in corpora cavernosa (CC). Also cGMP metabolising activity was higher in CC than in VD. However, both tissues share the same sensitivity to a broad panel of cGMP-related PDE inhibitors: sildenafil, tadalafil, dipyridamole, zaprinast, vinpocetine, EHNA and cilostamide. Based on the rank order of potency of these PDE inhibitors, we found that the cGMP metabolizing activity in human VD mostly corresponds to PDE5. PDE5 was immunolocalized in all the muscular layers of human and rabbit VD and was found to be negatively involved in regulating NO-induced relaxation. In addition, by using a rabbit model of hypogonadotropic hypogonadism, we found that PDE5 gene expression and activity are androgen-dependent in VD, as previously demonstrated in CC. In fact, the sensitivity to a NO-donor (NCX4040), its enhancement by PDE5 inhibitors and the PDE5-related cGMP breakdown were all affected by androgen manipulation. Our results provide a hypothesis explaining the beneficial effects of PDE inhibitors in patients with rapid ejaculation.

[The colecistectomy in primary sclerosing cholangitis: case report and review of literature]

Primary sclerosing cholangitis (PSC) is an idiopathic chronic inflammatory condition affecting intra- and extra-hepatic biliary system. The aim of this study is to stress the importance of cholecystectomy in patients with PSC. Consideration should be given to performing a cholecystectomy in PSC patients with gallbladder adenomyomas or calculi, even asymptomatic; this happens in approximately 15% of cases.

The role of Echo Colour/Power Doppler and magnetic resonance in expansive parotid lesions

The purpose of this research was to evaluate the role of Echo Colour/Power Doppler and Magnetic Resonance Imaging (MRI) in the diagnosis of expansive parotid lesions, and to establish criteria for differential diagnosis between benign and malignant forms. Forty nine patients (23 males and 26 females), aging from 30 to 85 years, with an expansive pathology of parotid gland were enrolled in our study from February 1999 through August 2004. Each patient was carefully assessed employing both ultrasonography integrated with Color/Power Doppler and MRI. Eventually, all patients received echo-guided needle-biopsy and surgical excision of the parotid lesion. Preliminary ultrasound assessed site, size, echoic appearance and margins of the lesion. In order to assess blood supply by means of Colour/Power Doppler, we divided the patients in four groups. Our MRI diagnostic criteria included site, size, intensity of signal, behaviour of the lesion after i.v. contrast, relationship with facial nerve and retromandibular vein, detection of margins and proximity to adjacent structures. On the basis of our results, the Authors concluded that both Echo Colour/Power Doppler and MRI play a very important role in the diagnosis and surgical planning of parotid gland lesions.

[Appendiceal lithiasis: case report and review of literature]

Appendiceal calculi are found in a limited percentage of patients. They are in association to an elevated prevalence of necrotic appendicitis and perforation of the appendix. The Authors report a case of acute appendicitis associated to appendiceal lithiasis with perforation of the organ. They emphasize the possibility to perform a preventive appendectomy in case of incidental appendiceal lithiasis. Besides they consider the differential diagnosis of the calcified images located in the lower abdominal quadrants with the aid of the various imaging methods available today, particularity sonography and computerized tomography.

Reduction of risk factors for cardiovascular diseases in morbid-obese patients following biliary-intestinal bypass: 3 years' follow-up

BACKGROUND

Obese patients are often affected by hypertension, dyslipidaemia, impaired glucose metabolism, and suffer from cardiovascular disease (CVD), related to the characteristic metabolic alterations.

AIM OF THE STUDY

To evaluate reduction of risk factors for CVDs in morbid-obese patients (body mass index (BMI)>40 kg/m2) after weight loss upon bariatric surgery intervention of biliary-intestinal bypass.

SUBJECTS

45 (17 men, 28 women) morbid-obese patients (age: 19-49 y, BMI>40 kg/m2). All patients were selected on the basis of medical history, physical and biochemical evaluation and of psychiatric tests, which were performed on all individuals admitted to our Day Hospital to verify the safety of surgical intervention.

MEASUREMENTS

Body weight, body composition (by dual X-ray absorptiometry, DXA), blood pressure, lipid profile, fibrinogen and glucose metabolism were monitored at baseline and 1, 3, 6, 9, 12, 24 and 36 months after surgery.

RESULTS

A significant and persistent weight loss was present in all patients at the end of the 3 y follow-up period (P<0.001), with a progressive reduction of total and trunk fat mass as evaluated by means of DXA. Additionally, a parallel significant reduction in systolic (P<0.001) and diastolic (P<0.001) blood pressure was observed. Total and LDL cholesterol were significantly reduced (P<0.001), while HDL showed no modifications; triglycerides declined progressively during the 3 y follow-up (P<0.001). Fibrinogen decreased from 364.5+/-82.4 to 266.4+/-45.7 mg/dl at the end of the period (P<0.001). Fasting glucose levels and glucose levels 120 min after an oral glucose tolerance test were reduced from 95.1+/-20.3 to 78.6+/-9.1 mg/dl (P<0.001) and from 116.9+/-34.7 to 77.6+/-15.5 mg/dl (P<0.001), respectively, at baseline and at the end of the study. Moreover, fasting insulin decreased from 30.0+/-20.4 to 8.6+/-2.9 microUI/ml (P<0.001) after 3 y, while insulin levels after (120 min) oral glucose load decreased from 105.5+/-61.5 to 12.0+/-6.0 microUI/ml (P<0.001).

CONCLUSION

Our results show that biliary-intestinal bypass may represent a valid and alternative therapeutic approach in patients with morbid obesity since it induces a significant and stable reduction of body weight and obesity-related risk factors for CVD.

Lectin binding in the human umbilical cord from normally grown pregnancies and from pregnancies complicated by intra-uterine growth retardation with absent or reversed diastolic flow

The content and the distribution of the glycoconjugate sugar residues were investigated in the human umbilical cord from normally grown pregnancies and from pregnancies complicated by intra-uterine growth retardation with absent or reversed flow in the umbilical artery. The gestational age range was 29-41 weeks. For this purpose, a battery of eight horseradish peroxidase conjugated lectins was used (ConA, WGA, PNA, SBA, DBA, LTA, UEA I, and OOA; see text). Our data showed that in both study groups ConA, WGA and PNA (after neuraminidase digestion) and LTA, UEA I, and OOA reacted with Wharton's jelly and vessels of the umbilical cord from the first weeks of gestation considered. SBA reactivity was observed only in the amniotic epithelial cells of the jelly and in the endothelial cells of the vessels. The reactivity with the most part of the lectins decreased or was lacking in the various components of the umbilical cord between 39 and 41 weeks of gestation in the normal group and between 36 and 37 weeks of gestation in the pathological one. Moreover, the intensity of reactivity with ConA, WGA and PNA (after neuraminidase digestion) and LTA, UEA I, and OOA in the normal group and with PNA (before and after neuraminidase digestion) and LTA and OOA in the pathological one was stronger in the peripheral portion of the jelly with respect to the adventitial one. The reactivity with ConA and UEA I was stronger in the vein than in the arteries in both study groups. Some hypotheses are reported on the role played by the sugar residues in the normal and pathological umbilical cords.

Parotid gland cancer: a case report of a primitive adenocarcinoma arising from a multirecurrent pleomorphic adenoma

Parotid tumours represent a wide group of tumours which are mostly localized in the major salivary glands. We report a case of a 69-year old female with a parotid tumour history who was referred to us with a prominent lump and swelling localized in the right parotid area. In the period between 1985-2002, she was operated 5 times elsewhere for a recurrent pleomorphic adenoma of the right parotid (mixed tumour until 1991), which was histologically confirmed. Sixteen years after the primitive tumour, she underwent mastectomy and axillary dissection for a ductal carcinoma. Routine follow-up has been conducted on both malignancies. Pleomorphic adenoma is the most frequent tumour of the parotid. The potential risk of a malignant transformation can increase over the years with an incidence of 1% to 7%. Management of these recurrences is complex and controversial because of the different treatment options advocated such as radical resection with possible facial nerve sacrifice, or postoperative radiotherapy in non radical cases.

[Collateral effects of intraoperative hyperthermic chemotherapy in peritoneal carcinomatosis]

The association between chemotherapy and hypertermia produces a synergic effect. In this study the Authors present their experience, by the analysis of the results. From 1993 to 2000, 17 patients have been treated with surgery associated with hypertermic chemotherapy for peritoneal carcinomatosis. For the management of these patients a constant cooperation among surgeon, cardiologist and anaesthetist is very important.

Distributional map of the terminal and sub-terminal sugar residues of the glycoconjugates in the prepubertal and postpubertal testis of a subject affected by complete androgen insensitivity syndrome (Morris's syndrome): lectin histochemical study

In the present research we have investigated the distribution of the sugar residues of the glycoconjugates in the prepubertal and postpubertal testes of a subject with Morris's syndrome (CAIS, Complete Androgen Insensitivity Syndrome). For this purpose a battery of six horseradish peroxidase-conjugated lectins was used (SBA, PNA, WGA, ConA, LTA and UEAI). We have obtained a complete distributional map of the terminal and sub-terminal oligosaccharides in the tunica albuginea, interstitial tissue, lamina propria of the seminiferous tubules, Leydig cells, Sertoli cells, spermatogonia, mastocytes and endothelial cells. Furthermore the present study has shown that a large amount of sugar residues were detectable in the prepubertal and postpubertal testes but that some differences exist with particular regard to the Sertoli cells. The Sertoli cells and the Leydig cells of the retained prepubertal testis of the patient affected by Morris's syndrome were characterized by the presence of alpha-L-fucose, which was absent in the retained prepubertal testis of the normal subjects. Comparing the results on the postpubertal testis with those obtained on the same aged testis of healthy subjects we have demonstrated that alpha-L-fucose in the Sertoli and Leydig cells and D-galactose-N-acetyl-D-galactosamine in the Leydig cells are a unique feature of the subject affected by Morris's syndrome. D-galactose (ss1,3)-N-acetyl-D-galactosamine and sialic acid, which are present in the Leydig cells of the normal testis were never observed in the same cells of the postpubertal testis of the CAIS patient.

EFFECTIVENESS AND SAFETY OF CHOLINESTERASE INHIBITORS IN ELDERLY SUBJECTS WITH ALZHEIMER’S DISEASE: A “REAL WORLD” STUDY

Clinical trials have demonstrated the efficacy of cholinesterase inhibitors (ChEI) in improving cognitive status and disability in subjects with mild to moderate Alzheimer's disease (AD). However, little is known about the effectiveness of ChEI in clinical practice, and no large clinical trials comparing different ChEI are available at present. Aim of this study was to evaluate safety and effectiveness of ChEI in a sample of elderly outpatients diagnosed with mild to moderate AD. We selected 407 subjects for ChEI treatment (donepezil,rivastigmine or galantamine). Their cognitive function was evaluated by means of the mini mental state examination (MMSE), and the global functional status was estimated by using the activities of daily living (ADL) and the instrumental activities of daily living (IADL) scales at baseline (To), then after 1 (T1), 3 (T2) and 9 months (T3), respectively. T3 follow-up was completed by 212 subjects. The patients were considered as responders (R), if the MMSEscore at T2 was unchanged or improved, if compared to that of T0. In 35 patients (8.6 %)treatment was withdrawn because of mostly gastrointestinal adverse events. Compared to the other drugs, donepezil was associated with a lower incidence of withdrawals due to adverse events. Subjects who completed T3 follow-up (age 78 +/- 6 years, MMSE scores 18.8 +/- 3.9) showed an increase at T2 of 0.7 +/- 2.7 (p = 0.001) and a decrease at T3 of -0.6 +/- 3.4 (p = 0.008) in the MMSE scores, as compared to To . The ADL and IADL scores did not show significant changes at T2; however, both decreased significantly at T3. The patients Rat-T2 showed a better cognitive and functional outcome at T3 , compared to the nonresponders(NR-at-T2), displaying values of MMSE R-at-T2 0.4 +/- 3.1 vs. NR-at-T2 -3.0 +/- 2.5, p = 0.001, and ADL values of -0.3 +/- 1.2 vs. -0.7 +/- 1.3, p = 0.03, respectively. No significant difference was found in the changes of MMSE scores between donepezil and rivastigmine (galantamine was not included in the comparison due to the small number of treated subjects). In conclusion, in this sample of elderly subjects with mild to moderate AD,treated with ChEI, a small but significant decline in cognitive and functional status was observed after 9 months. Subjects who showed a good response to treatment after 3 months, had a better cognitive and functional outcome at 9 months. No significant difference in cognitive outcome was found between drugs, while donepezil was better tolerated.

[Diagnosis and treatment of distal bile duct carcinoma: our experience]

Bile duct carcinomas are known to be difficult to cure, due to frequent locoregional recurrence even after radical resection. The Authors analyze their experience in a study about 53 patients treated between October 1991-January 2002.

Florid cemento-osseous dysplasia. Report of a case in a white woman with both mandibular and maxillary involvement

Florid cemento-osseous dysplasia (FLCOD) is a rare pathological entity whose classification is not yet completely defined although its non-neoplastic clinical and histologic behaviour is very clear. FLCOD is a self-limiting lesion scarcely delimited from the surrounding healthy tissue and whose surgical treatment therefore is not elective, unless inflammatory signs are present. A case of a white woman with both mandibular and maxillary involvement is presented; she was referred to us for partial impaction of her lower 3(rd) molars. Standard radiographic and CT images are examined and the patient management is discussed.

Abnormal vascular network complexity: a new phenotypic marker in hereditary non-polyposis colorectal cancer syndrome

BACKGROUND

Hereditary non-polyposis colorectal cancer (HNPCC) (Lynch cancer family syndrome I (LCFS1) and II (LCFS2)) is one of the most common hereditary cancer disorders. HNPCC results from dominantly inherited germline mutations in mismatch repair (MMR) genes, leading to genomic instability and cancer. No predictive physical signs of HNPCC are available to date.

AIMS

Increased complexity in tumour associated vascular growth has been reported. Here, we tested the hypothesis that an increased vascular network complexity is a phenotypic marker for LCFS2.

METHODS

Fourteen subjects from an LCFS2 kindred (gene carriers, n=5; non-carriers, n=9) and 30 controls were examined. Fractal dimension (D) at two scales (D (1-46), and D (1-15), tortuosity (minimum path dimension, Dmin), and relative Lempel-Ziev complexity (L-Z) of the vascular networks from the lower gingival and vestibular oral mucosa were measured.

RESULTS

LCFS2 networks exhibited a significantly increased overall complexity at both larger (D (1-46): 1.82 (0.04) v 1.68 (0.08); p<0.0001) and smaller (D (1-15): 1.51 (0.11) v 1.20 (0.09); p<0.0001) scales, increased destructured randomness (L-Z: 0.77 (0.09) v 0.56 (0.03); p<0.0001), and decreased vessel tortuosity (DMIN: 1.02 (0.03) v 1.07 (0.04); p=0.0005) compared with control patterns. The vascular networks of LCFS2 gene carriers showed higher complexity at the smaller scale (D (1-15): 1.59 (0.12) v 1.47 (0.07); p=0.034), and higher destructured randomness (L-Z: 0.85 (0.11) v 0.73 (0.05); p=0.013) than those of non-carriers.

CONCLUSIONS

Increased oral vascular network complexity is a previously unrecognised phenotypic marker for LCFS2, and is related to gene mutation carrier status.

Effects of hypoxia on endothelin-1 sensitivity in the corpus cavernosum

The penis remains in a hypo-oxygenated, flaccid state for a large majority of the time. In this study, we investigated the effect of changing oxygen tension on the expression and functional activity of endothelin-1 (ET-1) receptors in the penis. Experiments were performed in rabbit and human corpora cavernosa (CC) as well as in human fetal penile tissue and cell cultures [human fetal penile endothelial cells (hfPECs) and human fetal smooth muscle cells (hfPSMCs)]. Endothelin A (ETA) receptors are expressed by both endothelial and muscular cells in all tissues investigated. Only penile endothelial cells express endothelin B (ETB) receptors, which are further turned on during experimental hypoxia. In addition, hypoxia also allows ETB expression in the muscular compartment without affecting ETA expression. This hypoxia-induced over-expression of ETB decreased the contractile activity of ET-1 and increased ETB-mediated relaxation. The latter was essentially related to increased ETB-mediated nitric oxide formation in hfPEC and even in hfPSMC. Hypoxia also induced a time-dependent down-regulation of RhoA and Rho kinase (ROK) expression which, in turn, participated in the decreased contractile activity of ET-1 in the hypoxic penile tissue. Accordingly, during hypoxia, an ROK inhibitor, Y27632, was less effective in relaxing ET-1-precontracted strips. In conclusion, prolonged (24 h) hypoxia stimulated several counter-regulatory mechanisms in penile tissue, including up-regulation of ETB and down-regulation of RhoA/ROK pathways, which may help to preserve CC hypo-oxygenation, allowing smooth muscle relaxation and, most probably, penile erection.

Mesenteric cystic lymphangioma causing intestinal occlusion in an adult patient

Cystic lymphangioma is a benign tumor of uncertain etiology characterized by a slow growth; in 2-8% of cases it is localized in the mesentery. Symptomatology is aspecific and preoperative diagnosis is often difficult. The Authors report the case of a mesenteric cystic lymphangioma in a patient who had undergone subtotal colectomy eight years earlier for an adenocarcinoma occluding the sigmoid colon. The patient was hospitalized for intestinal occlusion.

[Magnetic resonance of the knee: possibility and current indications]

MRI is a multiparametric, multiplanar, non-invasive largely employed tool for assessing osseous, ligamentous and tendineous injuries, inflammatory and degenerative changes of the knee. Although its wider availability and the lack of ionizing radiations MRI should be used only if clinically useful in patient management, in a appropriate diagnostic iter including plain film and/or ultrasound examination. The aim of our work is to review possibilities, limits and current indications for MRI assessment of diseases of the knee.

Lectin binding in the human foetal testis

In the present study we have investigated the oligosaccharidic content of the glycoconjugates within the human foetal testis starting from its earliest differentiation phase (8, 10 and 12 weeks of gestation). To this purpose we have used a battery of six horseradish peroxidase-labelled lectins (SBA, PNA, WGA, UEAI, LTA and ConA). We have obtained a complete distributional map of the sugar residues of the glycoconjugates in the coelomic mesothelium, tunica albuginea, pre-Sertoli cells, pre-gonocytes, Leydig cells, basement membrane of the sex cords, interstitial tissue, mastocytes and endothelial cells of the capillary vessels. Since the beginning of the testis differentiation phase the cells of the coelomic mesothelium showed a large amount of sugar residues. In the pre-Sertoli cells and in the pre-gonocytes a role played as structural molecules by some oligosaccharides could be hypothesized. D-galactose-(beta1-->3)-N-acetyl-D-galactosamine, sialic acid, N-acetyl-D-glucosamine and alpha-D-mannose could be involved in inducing and maintaining the cellular activity of the Leydig cells.

Differential patterns of hybridization and introgression between the swallowtails Papilio machaon and P. hospiton from Sardinia and Corsica islands (Lepidoptera, Papilionidae)

Proportions of hybridization and introgression between the swallowtails Papilio hospiton, endemic to Sardinia and Corsica, and the holarctic Papilio machaon, were characterized using nine fully diagnostic and two differentiated allozyme loci and a mitochondrial DNA marker. Very low frequencies of F1 hybrids were detected in both Sardinia (0-4%, average 1.4%) and Corsica (0-3%, average 0.5%), as well as of first generation backcrosses (B1). No F2 were observed, in agreement with the hybrid breakdown detected in laboratory crosses. In spite of this minimal current gene exchange, specimens carrying introgressed alleles were found in high proportions in P. machaon but in lower proportions in P. hospiton. Introgression apparently occurred through past hybridization and repeated backcrossing, as evidenced by hybrid index scores and Bayesian assignment tests. Levels of introgression were low (0-1%) at two sex-linked loci and mitochondrial DNA, limited (0.4-2%) at three autosomal loci coding for dimeric enzymes, and high (up to 43%) at four autosomal loci coding for monomeric enzymes. Accordingly, selective filters are acting against foreign alleles, with differential effectiveness depending on the loci involved. The low levels of introgression at sex-linked loci and mitochondrial DNA are in agreement with Haldane's rule and suggest that introgression in P. machaon proceeds mainly through males, owing to a lower fitness of hybrid females. Papilio machaon populations showed higher levels of introgression in Sardinia than in Corsica. The role of reinforcement in the present reproductive isolation between P. machaon and P. hospiton is examined, as well as the evolutionary effects of introgressive hybridization between the two species.