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P Colombo

Publications and source records attributed to P Colombo.

At least 91 records · Page 5Linked to original sources
PubMed1997

Crystal dissolution-controlled release systems. II. Metronidazole release from semicrystalline poly(vinyl alcohol) systems.

Novel semicrystalline, poly(vinyl alcohol) (PVA)-based phase erosion systems were developed. The rate of drug release from these systems is controlled by the rate of crystal dissolution. PVA devices loaded with metronidazole were exposed to temperatures ranging from 90 to 120 C for times of 10-90 min to obtain samples with different degrees of crystallinity. Degrees of crystallinity were measured by differential scanning calorimetry and attenuated total reflectance Fourier transform infrared spectroscopy. In vitro release of metronidazole from such systems into deionized water at 37 degrees C was monitored. The influence of parameters such as polymer molecular weight, annealing time and temperature, and surface pretreatment on the crystal dissolution, and hence the drug release rate, were investigated. Measurements of water-front movements were carried out to study the effect of parameters such as drug solubility on the release rate. The drug release rate was found to be dependent on the crystallization conditions of the samples. Surface pretreatment was found to reduce the burst effect observed during the release.

Antitrichomonal Agents↗
PubMed1997

Assay of acyclovir in human skin layers by high-performance liquid chromatography.

This paper describes an assay procedure for acyclovir quantification in human skin after in vitro transdermal transport experiments. The procedure employs warm distilled water for acyclovir (ACV) extraction and high-performance liquid chromatography (HPLC) as analytical method. The procedure has good reproducibility, sensitivity and specificity, resulting in a reliable method for biopharmaceutical studies of ACV distribution in skin tissue. The chromatographic conditions set up, using distilled water as mobile phase, makes the analytical procedure simple and easy to perform.

Acyclovir↗
PubMed1997

Drug reservoir composition and transport of salmon calcitonin in transdermal iontophoresis.

PURPOSE: The aim of the work was to study iontophoretic transdermal administration of salmon calcitonin (sCt) in rabbits, with particular attention to drug reservoir composition. A dry sCt disc, to be dissolved on the application site, was used for preparing the reservoir for transdermal iontophoresis. As a reference drug reservoir, a pad wetted with drug solution was used. METHODS: Experiments were done in rabbits depositing 100 IU of salmon calcitonin on skin and applying anodal iontophoresis. Serum calcium concentration was measured during iontophoresis, passive diffusion and after i.v. administration. Parameters such as pH value and reservoir type were examined. RESULTS: Transdermal iontophoresis of sCt elicited a decrease in the serum calcium level, whereas, in the absence of electric current, no significant fall was measured. Using the reservoir prepared from drug solution, anodal iontophoresis at pH 4.2 was more effective than at pH 7.4, probably due to higher sCt net positive charge. Using the reservoir prepared from dry disc, similar kinetics and extent of drug effect were observed at both pH values. The reservoir prepared from solid drug deposit concentrated sCt next to the skin. CONCLUSIONS: Anodal iontophoresis for transdermal calcitonin administration shows therapeutical applicability. The type of reservoir is an important parameter affecting sCt transdermal iontophoresis.

Administration, Cutaneous↗
PubMed1997

Effect of desmopressin on ACTH and cortisol secretion in states of ACTH excess.

OBJECTIVE: To assess the ability of desmopressin administration to stimulate ACTH/cortisol secretion in patients with Cushing's disease, either before or after surgery, and in patients with other states characterized by ACTH hypersecretion, and to compare the results with those obtained after CRH testing. DESIGN AND SUBJECTS: Plasma ACTH and serum cortisol levels were evaluated after the administration of desmopressin (10 micrograms i.v.), CRH (1 microgram/kg i.v.) and saline on different days in 17 patients with Cushing's disease, 1 with occult ectopic ACTH syndrome, 5 with Addison's disease, 3 who had been bilaterally adrenalectomized for Cushing's syndrome and 4 normal subjects. After pituitary adenomectomy desmopressin and CRH were administered again to 13 of the patients who had undergone pituitary surgery for their Cushing's disease. RESULTS: In 16 patients with Cushing's disease with microadenoma a positive ACTH/cortisol rise occurred in 11 patients after both desmopressin and CRH, 2 other patients were responsive only to desmopressin and 2 only to CRH, while in 1 patient equivocal responses to both tests were found. The persistence of a hormonal response to desmopressin after pituitary adenomectomy for Cushing's disease correlated with unsuccessful surgery, while, contrary to CRH, absent ACTH/cortisol rises were found in cured patients 1 and 12 months after operation. In 1 patient suspected for ectopic ACTH hypersecretion, desmopressin and CRH administration did not cause any ACTH/cortisol rise. Significant ACTH rises occurred after both desmopressin and CRH testing in patients with Addison's disease. All the 3 patients adrenalectomized for Cushing's syndrome showed a rise of ACTH levels after CRH, while a similar response after desmopressin occurred in only one of them. CONCLUSIONS: Desmopressin is able to stimulate ACTH and hence cortisol release in Cushing's disease. It may be a useful test in patients with doubtful responses to CRH test, in those exhibiting responses to CRH indistinguishable from those of normal subjects and in the postoperative follow-up of Cushing's disease. In some patients with abolished or reduced cortisol feed-back at hypothalamic-pituitary level the sensitivity of normal corticotrophs to desmopressin is enhanced.

ACTH Syndrome, Ectopic↗
PubMed1997

Isolation and characterization of two cDNA clones coding for isoforms of the Parietaria judaica major allergen Par j 1.0101.

Two cDNA clones named P9* and P1* of 794 and 631 bp, respectively, were isolated from a lambda ZAP cDNA expression library using Parietaria judaica (Pj) pollen-specific IgE antibodies from a pool of sera (n = 23) of patients allergic to Pj. Sequence analysis showed open reading frames of 176 and 138 amino acids. Both clones contain a putative signal peptide giving two mature processed proteins named Par j 1.0102 of 14,726 D and Par j 1.0201 of 10,677 D. These proteins represent isoallergenic forms of the major Pj allergen Par j 1.0101 (clone P5) previously reported. The Par j 1.0102 shared 98% amino acid sequence homology with the P5, while the Par j 1.0201 shared 89% homology. Since P1, P5 and P9 clones were expressed in Escherichia coli, and since the three allergenic proteins shared a very high degree of sequence identity and comparable binding to the Pj-specific IgE, we decided to analyze in more detail the immunological properties of only one allergen, the recombinant Par j 1.0101. The allergenic activity determined by the histamine release assay ranged between 9 and 56%, depending on the allergic patient analyzed, while it blocked approximately 40% of all the Pj-specific IgE antibodies, as detected after ELISA and cross-absorption analysis.

Allergens↗
PubMed1997

Prognostic value of pulmonary hypertension in patients with chronic interstitial lung disease referred for lung or heart-lung transplantation.

BACKGROUND: The purpose of this study was to identify precise and reliable prognostic parameters in patients affected by serious chronic interstitial lung disease, who were undergoing screening for lung or heart-lung transplantation. METHODS: Hemodynamic and respiratory function parameters of 67 patients (43 with idiopathic pulmonary fibrosis, 18 with histiocytosis X, and 6 with lymphangioleiomyomatosis) undergoing clinical screening for lung transplantation. RESULTS: Statistical analysis showed that hemodynamic and respiratory function parameters in patients affected by histiocytosis X and idiopathic pulmonary fibrosis were not related to survival time. Moreover, the degree of pulmonary hypertension showed no correlation between respiratory function parameters in all the groups of diseases examined. Patients affected with histiocytosis X, even with higher degrees of pulmonary hypertension, had a better survival rate (p < 0.0005) compared with patients with idiopathic pulmonary fibrosis. CONCLUSIONS: Hemodynamic and respiratory parameters obtained during the clinical screening for lung transplantation do not predict survival and cannot be used as prognostic indicators.

Adult↗
PubMed1997

[Hepatitis C virus and mixed cryoglobulinemia in dialysis].

Prevalence of hepatitis C virus (HCV) varies in the dialytic population according to the geographic area (5-85%); the European average is 19%, with marked differences between dialysis units. The means of virus transmission is still not clear and represents one of the major management problems faced by dialysis units. US authors and European study groups have recently demonstrated a high level od HCV infection in patients with essential mixed cryoglobulinemia (EMC), suggesting that the virus plays an etiological role. The authors examined the correlation between mixed cryoglobulinemia and HCV and the possible etiological role of the virus in the pool of patients undergoing dialysis at the Centre. In September 1994 28/63 (44.4%) patients were found to be Ab anti-HCV positive (second and third generation ELISA); circulating cryoglobulins identified as Type II following immunofixation were found in 2/28 patients (7%) using centrifugation and cold incubation techniques. In the absence of the pathologies classically associated with cryoglobulinemia, the patients were diagnoses as suffering EMC. The HCV/EMC correlation in the dialysed population has been analysed in a limited number of studies, with discrepant results (0-47%). This paper highlights the association between HCV and EMC in 7% of chronic dialysed patients and given that the finding of anti-HCV Ab in serum solely documents previous exposure to the virus, we can only indirectly attribute an etiological role to HCV. The search for viral RNA in the serum, cryocrit and surnatant of patients found affected by EMC may provide additional etiopathogenetic information.

Aged↗
PubMed1996

cDNA cloning, sequence analysis and allergological characterization of Par j 2.0101, a new major allergen of the Parietaria judaica pollen.

A clone (P2) coding for an allergen of Parietaria judaica (Pj) pollen has been isolated and sequenced from a cDNA library in lambda ZAP using a pool of 23 sera from Pj-allergic patients. The clone contained an insert of 622 nucleotides with an open reading frame of 133 amino acids (aa) and a putative signal peptide of 31 aa giving a deduced mature processed protein of 102 aa with a molecular mass of 11344 Da. The expressed recombinant protein, named rPar j 2.0101, was a major allergen since it reacted with IgE of 82% (23/28) of the sera of Pj-allergic subjects analyzed. It was shown to be a new allergen since (i) the amino acid sequence homology with the already reported recombinant allergen Par j 1.0101 was 45% and (ii) there was no cross-inhibition between rPar j 2.0101 and rPar j 1.0101. In addition, rPar j 2.0101 inhibited 35% of the specific IgE for 10-14 kDa native allergens and preincubation of sera from Pj-allergic patients with both rPar j 2.0101 and rPar j 1.0101 fully abolished the IgE recognition of the 10-14 kDa native allergen region, suggesting that these two allergens contributed to the region.

Allergens↗
PubMed1996

cDNA sequence analysis and expression of the expression of the ribosomal protein S24 during oogenesis and embryonic development of the sea urchin Paracentrotus lividus.

A gene for the Paracentrotus lividus ribosomal protein S24, called P1-S24, has been isolated and sequenced. Ribosomal protein P1-S24 consists 130 amino acids and has a molecular weight of 14869 Da. Sequence analysis shows a high percentage (90%) identity with the corresponding gene of Strongylocentrotus purpuratus. Hybridization of the cDNA to digested sperm DNA suggests that P1-S24 is represented in no more than two copies. Studies of the temporal expression of P1-S24 gene indicate a good correlation between this and the expression of the rRNA genes both during oogenesis and embryonic development.

Amino Acid Sequence↗
PubMed1996

The human L35a ribosomal protein (RPL35A) gene is located at chromosome band 3q29-qter.

Using a polymerase chain reaction (PCR)-based strategy that distinguishes functional intron-containing genes from pseudogenes, the chromosomal location of the human intron-containing L35a ribosomal protein gene (rpL35a, HGMW-approved symbol RPL35A) was previously deduced to be onchromosome 18 using DNAs from a panel of human-rodent somatic cell hybrids. The inability to detect rpL35a in a human-hamster somatic cell hybrid containing only human chromosome 18 led to a reinvestigation of the chromosomal location of the human rpL35a gene. A clone containing intron 2 of rpL35a was isolated, sequenced, and used to isolate a P1 clone containing the human intron-containing rpL35a gene. By fluorescence in situ hybridization (FISH) analysis with the P1 clone as a probe, the rpL35a gene was located on chromosome band 3q29-qter. This location was confirmed by positive PCR analysis of a human-hamster somatic cell hybrid containing only human chromosome 3. The problem of using only human-rodent somatic cell hybrids for chromosome location is discussed.

Amino Acid Sequence↗
PubMed1996

Isolation of proteins and nucleic acids by electrophoresis on disposable gel columns.

A simple and cheap one-step method to isolate proteins or nucleic acids by electrophoresis in disposable gel columns is reported. A disposable syringe was modified to host a gel column and an elution chamber. Starting from a crude extract of E. coli, the laboratory-made devise allowed the isolation of the maltose binding protein (MBP) fused to a recombinant allergenic molecule with a molecular mass of 58 kDa, from a mixture of several proteins. Also, plasmid DNA could be isolated from a mixture containing chromosomal DNA and RNA, avoiding the use of organic solvents. Electrophoresis was performed at 150 V, 35 degrees C, pH 8.0 and 8.3 for protein and DNA, respectively. The protein or the DNA obtained showed a yield of 80% and a purity grade of 90%, as estimated by densitometry.

ATP-Binding Cassette Transporters↗
PubMed1996

Delivery of nasal powders of beta-cyclodextrin by insufflation.

PURPOSE: Delivery of nasal powders of granulated beta-cyclodextrin by insufflation was studied in order to find the relationship between powder properties and delivery behavior. METHODS: Three nasal powder formulations, prepared by granulating beta-cyclodextrin with different binders, were delivered from a powder insufflation device, in which the dose to be emitted was loaded in a gelatin capsule. The delivery sequence of powder was recorded and characterized using an image analysis program. RESULTS: Particle size was the main parameter affecting nasal powder delivery, both as to the amount of dose sprayed and the aspect of cloud produced. Between 50-150 mu m of particle size a substantial change in delivery behavior of powders was observed. Powder of around 100 mu m in size showed useful insufflation characteristics for nasal delivery. Bioavailability of nasal formulations of progesterone/beta-cyclodextrin powders was discussed in term of delivery behavior. CONCLUSIONS: The formulation approaches for improving nasal delivery of powders require the use of size optimized carriers. Insufflation of powders over 50 mu m can favour the particle deposition by impaction, whereas for powders below 50 mu m, deposition by sedimentation is moved. beta-cyclodextrin is a suitable carrier for achieving high systemic availability following nasal administration of powder formulations.

Administration, Intranasal↗
PubMed1996

Three-step immunoscintigraphy with anti-chromogranin A monoclonal antibody in tumours of the pituitary region.

In the present paper we evaluated the ability of pretargeted immunoscintigraphy (ISG) with antichromogranin A (CgA) monoclonal antibody (Mc-ab A11) in visualizing pituitary masses. The results obtained in 23 patients are described along with those of [111In]pentetreotide scintigraphy (Octreoscan) in 18 cases. Positive ISG was obtained in 9/11 (82%) non-functioning, 1/4 growth hormone-, 1/2 prolactin-, 1/2 thyrotropin-, 1/1 follicle-stimulating hormone-, 0/1 adrenocortico-trophin-secreting pituitary adenomas. In one patient with a positive ISG scan of a non-functioning pituitary adenoma, an associated neurinoma of the acoustic nerve was not imaged. The same occurred in one patient with a pituitary deposit from a mammary carcinoma and in another one with a cyst of the Rathke's pouch. Chromogranin A immunohistochemistry, carried out in 10 tumours, was positive in eight pituitary adenomas and negative in two non-adenomatous lesions. A concordant ISG occurred in all cases except for two pituitary adenomas: one cystic and necrotized and one post-operative remnant very small in size. In 18 patients with pituitary adenoma both ISG and Octreoscan were positive in 61% of cases but with a different distribution among tumours. At variance with ISG, Octreoscan visualized only 5/10 (50%) non-functioning pituitary adenomas and all (4/4) somatotropinomas. In conclusion, ISG is able to image pituitary tumours and particularly non-functioning pituitary adenomas. In this respect, it may be helpful in discriminating non-neuroendocrine masses of the pituitary region from non-functioning pituitary adenomas.

Adolescent↗
PubMed1996

[Evaluation of pathogenesis of encephalocele, high spina bifida and congenital clubfoot not forming part of any known syndrome: a case report].

The authors report the case, non forming part of any known syndrome, of a newborn with encephalocele, high cranial schisis, ocular anomalies, cleft palate and congenital clubfoot. The photographic documentation of the malformations is not possible due to a technical error in taking the photographs (lack of light in the room). Alterations to cerebral nervous tissue were histologically and cytologically characterised by immaturity and block of normal development during the early stages. For this reason the alteration of primary neuro-ectodermal tissue appears to be the initial factor with secondary involvement of anatomically and functionally contiguous fields and tissues, such as cranial bones and the eyes. The alteration of the nervous system resulted in the incapacity of the fetus to make fetal movements, making it vulnerable to extrinsic compression, above all uterine pressure. This led to the adoption of fixed postures with articular blockage most evident in the lower limbs (congenital clubfoot). The pathogenic noxa was not identified.

Anencephaly↗
PubMed1996

[Anti-c antibody neonatal hemolytic disease: a case report].

The authors present a case of neonatal hemolytic disease caused by incompatibility with the erythrocytic c antigen. The presence of this surface antigen may stimulate anti-c antibodies even in the presence of compatibility with factor D, the larger of the characters.

Antibodies↗
PubMed1996

Nephrolithiasis as a presenting feature of chronic sarcoidosis: a prospective study.

BACKGROUND AND AIM OF THE WORK: The presentation of sarcoidosis with renal stones has never been evaluated in a prospective study. DESIGN: We have studied 110 consecutive patients with histologically proven sarcoidosis, first seen in the years 1993-1994 in the Milan Sarcoid Clinic. Those who had renal stones preceding or suggesting the diagnosis of sarcoidosis, and those who had evidence of renal calculi at presentation, were studied up to 31 December 1995 with serial evaluation of calcaemia, calciuria and serum 1,25 (OH)2D3 and are the basis of this report. RESULTS: Four patients had had calculi a long time ago and probably unrelated to their sarcoidosis. Three patients had a previous history of recurrent colic with calculi. In one further patient the occurrence of calculi suggested the diagnosis. In three other patients pyuria or microscopic haematuria at the presentation of pulmonary sarcoidosis led to the diagnosis of asymptomatic calculi. All the above seven patients had features of chronic disease and required long term corticosteroid therapy. Four of them required lithotripsy or pyelotomy before starting steroid therapy. Another had further calculi during the follow-up, and an episode of hydronephrosis requiring lithotripsy, due to poor compliance to corticosteroid therapy. Another patient had a single stone during follow-up in spite of proper therapy. In all the others prednisone was useful to control the disease. Summing up the results of a previous similar but retrospective study from our clinic, we can describe the full spectrum of nephrolithiasis at presentation of sarcoidosis, as it appears from the examination of 729 consecutive patients seen over 17 years (1978-1994), with a further follow-up of at least one year (see Conclusions). CONCLUSIONS: 1. Renal stones may be the presentation of sarcoidosis in 3.6% of cases, but the etiology may go unrecognized for many years in most of them. 2. There are asymptomatic renal stones at presentation in a further 2.7%: pyuria or microscopic haematuria may suggest such an occurrence. 3. Renal calculi appear to be a marker of chronicity, with long term corticosteroid therapy required in most cases. 4. A diagnosis of sarcoidosis should always be considered when patients present with renal calculi of unknown origin.

Adult↗