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Biomedical subjects

M Porras

Publications and source records attributed to M Porras.

At least 19 recordsLinked to original sources
PubMed2006

Mast cell stabilizer ketotifen [4-(1-methyl-4-piperidylidene)-4h-benzo[4,5]cyclohepta[1,2-b]thiophen-10(9H)-one fumarate] prevents mucosal mast cell hyperplasia and intestinal dysmotility in experimental Trichinella spiralis inflammation in the rat.

Trichinella spiralis infection in rats induces hypermotility and an abnormal response to cholecystokinin (CCK) similar to motor disturbances observed in irritable bowel syndrome. Mast cell hyperplasia is also characteristic of this experimental model. The aim of our study was to correlate mast cell activity with the development of dysmotility and to demonstrate whether the mast cell stabilizer ketotifen [4-(1-methyl-4-piperidylidene)-4H-benzo[4,5]cyclohepta[1,2-b]thiophen-10(9H)-one fumarate] could prevent the development of intestine hypermotility. Sprague-Dawley rats were infected with T. spiralis and, 5 days after infection, treated with the mast-cell stabilizer ketotifen (10 mg/kg/day). Twelve days after infection, intestinal spontaneous motor activity and response to CCK were evaluated by means of strain-gauge transducers. Immunohistochemistry for rat mast cell protease II (RMCPII), cyclooxygenase (COX)-2, and inducible nitric-oxide synthase (iNOS) was performed in intestinal specimens. In addition, RMCPII and myeloperoxidase were determined in serum. Infected control rats showed hypermotility, mast cell hyperplasia, increased RMCPII levels, increased myeloperoxidase, and overexpression of COX-2 and iNOS. In contrast, ketotifen-treated rats showed spontaneous intestinal motility and CCK response similar to the noninfected control rats. Mast cell hyperplasia and RMCPII were reduced in ketotifen-treated rats. Inflammatory parameters were less modified by ketotifen, but those animals that received the longest ketotifen treatment showed a slight amelioration in these parameters. These results indicate that mast cells are implicated in the development of hypermotility. The treatment with ketotifen prevented hypermotility and mast cell hyperplasia and diminished mucosal mast cell activity.

Animals↗
PubMed2005

Cyclical upregulated iNOS and long-term downregulated nNOS are the bases for relapse and quiescent phases in a rat model of IBD.

We previously reported that indomethacin induces a chronic intestinal inflammation in the rat where the cyclical characteristic phases of Crohn's disease are manifested with a few days' interval and lasting for several months: active phase (high inflammation, hypomotility, bacterial translocation) and reactive phase (low inflammation, hypermotility, no bacterial translocation). In this study, we investigated the possible role of both constitutive and inducible isoforms of nitric oxide (NO) synthase (NOS) and cyclooxygenase (COX) in the cyclicity of active and reactive phases in rats with chronic intestinal inflammation. Rats selected at either active or reactive phases and from 2 to 60 days after indomethacin treatment were used. mRNA expression of both constitutive and inducible NOS and COX isoforms in each phase was evaluated by RT-PCR and cellular enzyme localization by immunohistochemistry. The effects of different COX and NOS inhibitors on the intestinal motor activity were tested. mRNA expression of COX-1 was not modified by inflammation, whereas mRNA expression of neuronal NOS was reduced in all indomethacin-treated rats. In contrast, NOS and COX inducible forms showed a cyclical oscillation. mRNA expression and protein of both iNOS and COX-2 increased only during active phases. The intestinal hypomotility associated with active phases was turned into hypermotility after the administration of selective iNOS inhibitors. Sustained downregulation of constitutive NOS caused hypermotility, possibly as a defense mechanism. However, this reaction was masked during the active phases due to the inhibitory effects of NO resulting from the increased levels of the inducible NOS isoform.

Animals↗
PubMed2005

Early surgery for ruptured cerebral arteriovenous malformations.

Acute surgery on cerebral arteriovenous malformations (AVMs) has seldom been reported or used. We reviewed 49 patients of ages 2 months to 78 years (mean 32.8 years), 32 male (65%) and 17 female (35%), treated acutely (within 4 days of bleed) in Helsinki Neurosurgery during 1997-2002. The following variables were assessed in regards to the outcome (Glasgow outcome score; GOS; 2-3 months after bleed): age, sex, Hunt and Hess Grade (HH), Spetzler-Martin Grade (SMG), location of AVM, size of intraparenchymal haematoma (ICH), and presence of intraventricular haemorrhage (IVH). Most of the patients were in a poor clinical condition on admission (two thirds were HH 4-5). 45 (92%) patients underwent extirpation of AVM and evacuation of ICH, within 4 days after bleed. Over 55% had good functional outcome. GOS correlated significantly with HH (p = 0.001), age (p = 0.006), and IVH (p = 0.049). On the other hand, SMG, location of AVM, and size of haematoma did not significantly predict the outcome. Microneurosurgery with preoperative embolization has made possible the excision of 90% of AVMs. It is our experience that it can be done acute and early, and it saves lives as compared to natural history of cerebral AVMs or late surgery, and accelerates rehabilitation of the patients.

Adolescent↗
PubMed2001

Factors affecting formation and growth of intracranial aneurysms: a long-term follow-up study.

BACKGROUND AND PURPOSE: We sought to investigate factors determining growth rate of unruptured intracranial aneurysms as well as formation of new (de novo) aneurysms in patients from a time period when unruptured aneurysms were not treated surgically. METHODS: Eighty-seven patients (79 had ruptured aneurysms clipped at start of follow-up) with 111 unruptured aneurysms as well as an additional 7 patients (2 with and 5 without unruptured aneurysms) who developed new aneurysms were followed from the 1950s to the 1970s until death or subarachnoid hemorrhage or until the last contact. Patients' cerebral arteries were examined later either with conventional (control) angiography (n=38) and/or, for those alive during 1996-1998, with 3-dimensional CT angiography (n=57). In addition, 10 patients were studied at neuropathological autopsy. RESULTS: Mean+/-SD duration of follow-up was 18.9+/-9.4 years (range, 1.2 to 38.9 years). Unruptured aneurysms increased in size >/=1 mm in 39 of the 87 patients (45%) and >/=3 mm in 31 (36%). New aneurysms were found in 15 of the 89 patients and in 5 without an unruptured aneurysm at the beginning of follow-up. Aneurysm rupture was associated very significantly (P:<0.001) with aneurysm growth during follow-up. Of several potential risk factors tested, only cigarette smoking (odds ratio [OR], 3.92; 95% CI, 1.29 to 11.93) and female sex (OR, 3.36; 95% CI, 1.11 to 10.22) were, after adjustment for age, significant (P:<0.05) independent risk factors for occurrence of aneurysm growth of >/=1 mm. Only cigarette smoking (OR, 3.48; 95% CI, 1.14 to 10.64; P:<0.05) was associated with growth of >/=3 mm. Age- and hypertension-adjusted risk factors for aneurysm formation were female sex (OR, 4.73; 95% CI, 1.16 to 19.38) and cigarette smoking (OR, 4.07; 95% CI, 1.09 to 15.15). CONCLUSIONS: Women and cigarette smokers are at increased risk for intracranial aneurysm formation and growth. Cigarette smoking in particular hastens aneurysm growth. Cessation of smoking is important for patients with unruptured aneurysms and possibly also for those with a prior subarachnoid hemorrhage.

Adolescent↗
PubMed2000

Natural history of unruptured intracranial aneurysms: probability of and risk factors for aneurysm rupture.

OBJECT: The authors conducted a study to investigate the long-term natural history of unruptured intracranial aneurysms and the predictive risk factors determining subsequent rupture in a patient population in which surgical selection of cases was not performed. METHODS: One hundred forty-two patients with 181 unruptured aneurysms were followed from the 1950s until death or the occurrence of subarachnoid hemorrhage or until the years 1997 to 1998. The annual and cumulative incidence of aneurysm rupture as well as several potential risk factors predictive of rupture were studied using lifetable analyses and Cox's proportional hazards regression models including time-dependent covariates. The median follow-up time was 19.7 years (range 0.8-38.9 years). During 2575 person-years of follow up, there were 33 first-time episodes of hemorrhage from previously unruptured aneurysms, for an average annual incidence of 1.3%. In 17 patients, hemorrhage led to death. The cumulative rate of bleeding was 10.5% at 10 years, 23% at 20 years, and 30.3% at 30 years after diagnosis. The diameter of the unruptured aneurysm (relative risk [RR] 1.11 per mm in diameter, 95% confidence interval [CI] 1-1.23, p = 0.05) and patient age at diagnosis inversely (RR 0.97 per year, 95% CI 0.93-1, p = 0.05) were significant independent predictors for a subsequent aneurysm rupture after adjustment for sex, hypertension, and aneurysm group. Active smoking status at the time of diagnosis was a significant risk factor for aneurysm rupture (RR 1.46, 95% CI 1.04-2.06, p = 0.033) after adjustment for size of the aneurysm, patient age, sex, presence of hypertension, and aneurysm group. Active smoking status as a time-dependent covariate was an even more significant risk factor for aneurysm rupture (adjusted RR 3.04, 95% CI 1.21-7.66, p = 0.02). CONCLUSIONS: Cigarette smoking, size of the unruptured intracranial aneurysm, and age, inversely, are important factors determining risk for subsequent aneurysm rupture. The authors conclude that such unruptured aneurysms should be surgically treated regardless of their size and of a patient's smoking status, especially in young and middle-aged adults, if this is technically possible and if the patient's concurrent diseases are not contraindications. Cessation of smoking may also be a good alternative to surgery in older patients with small-sized aneurysms.

Adolescent↗
PubMed2000

Natural history of unruptured intracranial aneurysms: probability and risk factors for aneurysm rupture.

OBJECT: The authors conducted a study to investigate the long-term natural history of unruptured intracranial aneurysms and the predictive risk factors determining subsequent rupture in a patient population in which surgical selection of cases was not performed. METHODS: We followed 142 patients with 181 unruptured aneurysms from the 1950s until death or the occurrence of subarachnoid hemorrhage, or until the years 1997 to 1998. The annual and cumulative incidence of aneurysm rupture as well as several potential risk factors predictive of rupture were studied using life-table analyses and the Cox's proportional hazards regression models including time-dependent covariates. The median follow-up time was 19.7 years (range 0.8-38.9 years). During 2575 person years of follow up, there were 33 first-time episodes of hemorrhage from a previously unruptured aneurysm, giving an average annual incidence of 1.3%. In seventeen of these cases, hemorrhages led to the patients' deaths. The cumulative rate of bleeding was 10.5% at 10 years, 23.0% at 20 years, and 30.3% at 30 years after diagnosis. The diameter of the unruptured aneurysm(relative risk [RR] 1.11 per mm in diameter, 95% confidence interval [CI] 1.00-1.23, p = 0.05) and patient age at diagnosis inversely (RR 0.97 per year, 95% CI 0.93-1.00, p = 0.05) were significant independent predictors for a subsequent aneurysm rupture after adjustment for sex, hypertension, and aneurysm group. Active smoking status at the time of diagnosis was a significant risk factor for aneurysm rupture (RR 1.46, 95% CI 1.04-2.06, p = 0.033) after adjustment for the size of the aneurysm, age, sex, presence of hypertension, and aneurysm group. Active smoking status asa time-dependent covariate was an even more significant risk factor for aneurysm rupture (adjusted RR 3.04, 95% CI 1.21-7.66, p = 0.020). CONCLUSIONS: Cigarette smoking, size of the unruptured intracranial aneurysm, and age, inversely, are important factors determining risk for subsequent aneurysm rupture. The authors conclude that such unruptured aneurysms should be surgically treated irrespective of their size and of patients' smoking status, especially in young and middle-aged adults, if this is technically possible and if the patient's concurrent diseases are not contraindications. Cessation of smoking may also be a good alternative to surgery in older patients with small-sized aneurysms.

Adolescent↗
PubMed1997

Anterior cervical myelopathy in the early postoperative period.

PURPOSE: The onset of anterior cervical myelopathy in the early postoperative period is an unusual complication after cardiac surgery without extracorporeal circulation in which haemodynamic stability was maintained. We report a patient who developed anterior cervical myelopathy after cardiac surgery. CLINICAL FEATURES: A 53-yr-old man with no serious associated medical problems underwent cardiac surgery without extracorporeal circulation to repair a ruptured left ventricle. Haemodynamic stability was maintained throughout the procedure but the patient developed flaccid paraparesis and dissociated sensory loss, three hours later. Early recognition of the clinical picture and prompt initiation of steroid treatment facilitated a successful outcome. The definitive diagnosis was based on magnetic resonance findings days after surgery. CONCLUSION: The onset or aggravation of neurological symptoms in the postoperative period may be avoided by thorough search for medullary pathology in the patient's background and by using particular care when performing manoeuvres during the perioperative period, not only to ensure haemodynamic stability, thus preserving medullary perfusion, but also to avoid mechanical compression of a spinal segment.

Cardiac Surgical Procedures↗
PubMed1993

Natural history of unruptured intracranial aneurysms: a long-term follow-up study.

To investigate the natural history of unruptured aneurysms and predictive risk factors determining subsequent rupture, the authors followed 142 patients with 181 unruptured aneurysms until death or subarachnoid hemorrhage intervened, or for at least 10 years after the unruptured aneurysm was diagnosed. Six patients had a symptomatic aneurysm, five had an incidentally discovered aneurysm, and 131 had multiple aneurysms, of which the ruptured lesion was clipped at the beginning of the follow-up study. The median follow-up time was 13.9 years (range 0.8 to 30.0 years). During 1944 patient-years of follow-up study there were 27 first episodes of hemorrhage from a previously unruptured aneurysm, giving an average annual rupture incidence of 1.4%. Fourteen of these bleeding episodes were fatal. The cumulative rate of bleeding was 10% at 10 years, 26% at 20 years, and 32% at 30 years after the diagnosis. The only predictor for the rupture was the size of the aneurysm (p = 0.036). However, in patients with multiple aneurysms (the main subgroup) the only variable that tended to predict rupture was the age of the patient: risk of rupture was inversely associated with age (p = 0.080). The median diameter of the aneurysms was 4 mm at the beginning of the follow-up period, both in those with and those without a later hemorrhage. During the angiographic monitoring period, a ruptured aneurysm significantly (p < 0.001) increased in size in 17 patients with hemorrhage but aneurysms did not increase significantly in 14 patients without hemorrhage. In addition, a new aneurysm was found in six of 31 patients. The authors conclude that an unruptured aneurysm should be operated on, irrespective of its size, if it is technically possible and the patient's age and concurrent diseases are not contraindications to surgery.

Adolescent↗
PubMed1991

Diagnosis of cysticercosis in endemic regions. The Cysticercosis Working Group in Peru.

Taenia solium cysticercosis is a frequent cause of neurological disease in developing countries. Specific diagnosis of cysticercosis is difficult. We obtained serum and/or CSF samples from 204 consecutive patients admitted to a neurological ward in Lima, Peru, and looked for antibodies specific for T solium with the enzyme-linked immunoelectrotransfer blot (EITB) assay. 21 (12%) of 173 serum samples from these patients were EITB-positive. In contrast, only 2 (1.5%) of 135 patients attending a public endoscopy clinic and 1 (1%) of 88 patients attending a private endoscopy clinic were seropositive. 1 (1%) of 98 pregnant women living in a Lima shanty town was EITB-positive. 15 (58%) of 26 neurology patients diagnosed clinically as having cysticercosis were seronegative. Routine screening by EITB of all patients with neurological symptoms from areas of endemic cysticercosis would avoid misdiagnosis of this common and treatable disease.

Adolescent↗
PubMed1990

Computed tomography and angiography do not reliably discriminate malignant meningiomas from benign ones.

Histological anaplasia, found in up to 10% of meningiomas, is an important prognostic sign as it is associated with increased recurrence rate and volume growth rate. We studied in retrospect a series of 230 primary intracranial meningiomas to discover whether histological anaplasia can be reliably foreseen in CT scans and angiograms. 205 meningiomas were histologically benign, and 25 meningiomas were classified as malignant (atypical or anaplastic), with either incipient (20) or overt (5) signs of anaplasia. Of ten CT parameters tested, three were associated significantly more often with malignant meningiomas: nodular contour (58.3% vs 26.7%), cysts (20.0% vs 4.4%) and absence of calcifications (92% vs 65.3%); none of these parameters was an absolute sign of anaplasia. 'Mushrooming', previously regarded as a definite sign of malignancy, was seen in 9% of benign meningiomas and in 21% of malignant ones. In angiography, no apparent differences between benign and malignant meningiomas were seen. The conclusion is that it is not possible to distinguish malignant meningiomas from benign ones with CT or angiography.

Anaplasia↗
PubMed1990

Functional results of facial nerve suture after removal of acoustic neurinoma: analysis of 25 cases.

The facial nerve is sometimes severed during the removal of acoustic neurinomas, either intentionally to ensure complete removal, or unintentionally because of difficulties in identification. In such cases we have, if possible, sutured the nerve stumps microsurgically, either end to end or by use of an intervening nerve graft. We analyzed the outcome of 25 instances of facial nerve suturing in a series of 219 patients operated on for acoustic neurinoma from 1979 to 1987. The first signs of recovery appeared at an average of 12 months, and there was continued improvement for several years. Recovery was graded from 1 to 6. The anastomosis was successful in 24 of the 25 sutured nerves, in that at least some facial movement and tone were restored (Grade 5 or higher). In 11 of the 25 cases, facial appearance at rest and with movement was moderately good (Grade 2 or 3). A Grade 1 result, with no perceivable facial dysfunction, was never achieved. Typically, oral muscles showed the most improvement and frontal muscles the least. Facial appearance was better at rest than with movement, which was always complicated by some degree of synkinesis. Closure of the eye was so good in 13 of the 25 cases that neither tarsorrhaphy nor an eyelid spring was necessary. When the facial nerve is severed, intraoperative suture is recommended, because it provides a chance for moderately good restoration of facial appearance.

Evaluation Studies as Topic↗
PubMed1990

Improved visualization of posterior fossa with clivoaxial CT scanning plane.

Eighteen patients clinically suspected of having acoustic neurinoma were studied in both orbitomeatal and clivoaxial (CA) (the plane perpendicular to clivus) CT scanning planes during the same sessions. On the CA cuts there were highly significantly less (p less than 0.001) artifacts. Also, the tentorium was highly significantly (p less than 0.001) better visualized on the CA cuts. CA cuts could be recommended in cases when artifacts disturb the diagnostics of posterior fossa pathology or when detailed topographic information about pathologic anatomy round the tentorium is needed.

Adult↗
PubMed1989

Validity of clinical tests in the diagnosis of root compression in cervical disc disease.

The purpose of this study was to test the validity of three clinical tests (the neck compression, the axial manual traction, and the shoulder abduction test) in the diagnosis of root compression in 43 patients with cervical disc disease. The validity was investigated regarding radicular pain, neurologic signs, and root compression signs in myelography. All tests were highly specific for the validity parameters. However, the sensitivity was low; it ranged from 26 to 50% for the three single validity parameters in roots C6-8, and from 40 to 64% for combined neurologic and radiologic signs. It is concluded that, despite low sensitivity, these tests are a valuable aid in the clinical examination of a patient with neck and arm pain.

Adult↗
PubMed1989

External fixation of Colles' fracture.

Radiographic and functional results of external fixation of 32 Colles' fractures were compared with the results of plaster fixation of 189 Colles' fractures. Despite the fact that the fractures treated with the external device were more unstable and comminuted, the final results were equal in both groups, and the radiographic outcome of external fixation was superior. Pin loosening decreased with predrilling rather than self-tapping. We recommend external fixation for unstable fractures of the distal forearm.

Adolescent↗