Biomedical subjects

R Visentin

Publications and source records attributed to R Visentin.

6 recordsLinked to original sources

PubMed2004

In vitro and in vivo characterization of Indium-111 and Technetium-99m labeled CCK-8 derivatives for CCK-B receptor imaging.

Cholecystokinin (CCK) receptors of the subtype B (CCK-BR) have been shown to be overexpressed in certain neuroendocrine tumors including medullary thyroid cancer. Our recent work has focused on new methods to radiolabel the CCK8 peptide with 111In or 99mTc for CCK-B receptor imaging. Derivatives of CCK8 were obtained by addition at the N-terminus in solid phase of a DTPA derivative (DTPAGlu) linked through a glycine spacer (DTPAGlu-G-CCK8) or cysteine, glycine and a diphenylphosphinopropionyl moiety (PhosGC-CCK8) for labeling with 111In and 99mTc, respectively. CCK-BR overexpressing A431 cancer cell lines were utilized to characterize in vitro properties of the two compounds as well as for generating xenografts in nude mice for in vivo characterization. Both 111In-DTPAGlu-G-CCK8 and 99mTcPhosGC-CCK8 showed similar binding affinities for CCK-BR with dissociation constants of 20-40 nM, were internalized after interaction with the receptor and displayed prolonged cellular retention times. Specific in vivo interaction with the receptor of both CCK8 analogs was observed in our animal model. 111In-DTPAGlu-G-CCK8 showed better target to non-target ratios, although it appeared to be rapidly metabolized after injection and activity cleared through the kidneys. 99mTc-PhosGC-CCK8 was more stable in vivo but showed marked hepatobiliary clearance with resulting high background activity in the bowel. The rapid clearance and lower background obtained with 111In-DTPAGlu-G-CCK8 make this a better candidate for further development.

Animals↗

PubMed2001

99mTc-labeling experiments on CCK(4) by a direct method.

99mTc-labeling studies have been performed on CCK(4) fragment of cholecystokinin, starting from 99mTc-pertechnetate, by using tin(II)pyrophosphate or tin(II)gluconate as reducing agents, together with NaBH(4) acting as a stabilizing agent of tin(II). Gluconate has been used as exchange ligand in the carrier added experiments and in the syntheses of 99Tc-CCK(4) and Re-CCK(4) complexes to be able to reproduce at macroscopic level the same chemical reactions occurring at non carrier added conditions. 99mTc-labeling yields higher than 95% have been achieved depending on Sn(II) concentration, CCK(4)/gluconate ratio, reaction time and applied temperature. The species produced with 99mTc, 99Tc, and cold rhenium nuclides have been compared by means of HPLC measurements, which showed similar retention times and thus probably the same species in the three situations.

Borohydrides↗

PubMed1998

Effects of deep vs. superficial stimulation of acupuncture on capsaicin-induced edema. A blind controlled study in rats.

The modality of needle stimulation in acupuncture is part of the concept of the ìintensityî of the stimulation, a variable indicating the ìdosageî of the treatment administered. In this study we intend to compare the effect of superficial and deep needle insertion in the leg ipsilateral or contralateral to the paw treated with capsaicin. Testing was carried out on 100 male Sprague-Dawley rats weighing 120-140 g, divided into 5 groups according to the treatment received. Group 1 [20 animals] was kept as control; Group 2 [20] received ipsilateral deep acupuncture stimulation; Group 3 [20] received ipsilateral superficial acupuncture stimulation; Group 4 [20] received contralateral deep acupuncture stimulation; Group 5 [20] received superficial contralateral acupuncture stimulation. Results show that both acupuncture modalities are efficient when administered ipsilaterally to the paw where capsaicin is injected, while contralaterally only deep stimulation shows a certain efficiency. It is possible to conclude that deep insertion has a greater efficiency, probably because it affects a greater number of receptors; stimulation is therefore of an intensity greater than that seen in superficial insertion.

Acupuncture Therapy↗

PubMed1997

Fine-needle aspiration cytology of the breast: a preliminary report on telepathology through Internet multimedia electronic mail.

Telepathology is a field of telemedicine that enables the exchange of histologic and cytologic images for consultations among pathologists of two or more remote institutions, through a suitable communication channel. The Internet can connect several scientific and medical institutions because of the existence of a set of standard protocols that allow different computers to communicate; multimedia electronic mail is one such protocol, which allows asynchronous transmission of multimedia documents, i.e., including text, images, movies, and sounds. The aim of the present article is to test a novel approach in which Internet multimedia electronic mail is used as a communication medium to obtain an asynchronous telepathology tool for remote consultation. To assess the diagnostic validity of the method, 48 cases of fine-needle aspiration cytology of breast lesions were sent from Udine to Trento, Italy. Comparisons between local and remote diagnoses, and cytologic diagnoses versus subsequent histologic reports demonstrated that Internet multimedia electronic mail is suitable for remote consultation. Internet multimedia electronic mail thus presents an additional diagnostic tool that is easy to use, available on a wide range of computers, and inexpensive, because its cost is independent of distance.

Biopsy, Needle↗

PubMedDate not supplied

The role of manual acupuncture and morphine administration on the modulation of capsaicin-induced edema in rat paw. A blind controlled study.

Neurogenic inflammation, includes vasodilation, the increase of vasal permeability and edema due to the release of neuromediators from nerve endings. A modulation of the release of neurotransmitters, from nerve endings and neurogenic inflammation related phenomena, was observed with the administration of drugs or of neurotransmitters inhibiting the release of neuropeptides from capsaicin-sensible neurons, among which morphine and other endogenous agonist opioids seem to be effective. The aim of this study is to verify the effect of acupuncture on the peripheral release of Substance P due to the injection of capsaicin in rat paw. The study was carried out on 44 male Sprague-Dawley divided in 3 groups according to the treatment they were submitted to. Group 1 [20 rats] were controls; group 2 [10 rats] was received intraperitoneal morphine chloridrate 5 mg/Kg; group 3 [14 rats] stimulated with manual acupuncture. Morphine is effective in controlling inflammatory response according to other Authors' results. Also manual acupuncture is effective in controlling the edematogenic response in a statistically significant way of comparison with controls.

Acupuncture Therapy↗

PubMedDate not supplied

The effects of parachlorophenylalanine and naloxone on acupuncture and electroacupuncture modulation of capsaicin-induced neurogenic edema in the rat hind paw. A controlled blind study.

OBJECTIVE: The aim of this work was to study the effect of pre-treatment with parachlorophenylalanine (PCPA) and posttreatment with naloxone on the modulating action on neurogenic inflammation of manual acupuncture and low intensity (5 mAmp), low frequency (5 Hz) electroacupuncture (EA). METHODS: Edema was induced by the subcutaneous administration of 50 micrograms capsaicin in rat paws. Pre-treatment with intraperitoneal PCPA was given for 3 days: 200 mg/Kg on the first day and 100 mg/Kg on the second and third days. Naloxone (1 mg/Kg) was administered at the end of the stimulation. RESULTS: The results show that naloxone and PCPA reduce the anti-edema effect of both manual acupuncture and EA. Combined administration of the two drugs completely eliminated the effect of manual acupuncture, and decreased but did not abolish the effect of electroacupuncture. CONCLUSION: These results indicate that both the opioid and the serotonergic inhibitory control systems are involved in the modulating action of acupunctural stimulation on neurogenic inflammation.

Animals↗