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Ganciclovir, a synthetic acyclic nucleotide analog of guanine, is phosphorylated to a triphosphate within the cell and acts as an inhibitor of viral DNA synthesis. Preliminary data have shown ganciclovir effective in the treatment of symptomatic congenital CMV infection. A phase II study with ganciclovir showed hearing improvement or stabilization in five of 30 infants with symptomatic congenital CMV infection at six months or later. During the treatment period, quantitative excretion of CMV in the urine decreased. However, after cessation of therapy, viruria returned to near pre treatment levels. A phase III randomized trial suggests that ganciclovir may benefit infants with severe congenital CMV infection. Central nervous system damage that has already occurred will not be reversed, but ongoing viral replication causing postnatal damage is controlled campared to untreated CMV-infected controls. The value of ganciclovir for the prevention or treatment of hearing loss in asymptomatic children has not been determined. Side effects of ganciclovir include bone narrow suppression and potential gonadal toxicity. Presently there is insufficient data to justify the routine use of ganciclovir in the treatment of congenital CMV infection.
CMV infection can be diagnosed by isolation of the virus from the urine or saliva within the first three weeks of life. This can be accomplished by traditional virus culture methods which may take one to two weeks to obtain a result or rapid culture methods (”shell vial assay”) using centrifugation to enhance infectivity and monoclonal antibody to detect early antigens in infected tissue culture cells which may yield results in 24 hours. Rapid diagnosis of CMV can also be accomplished by detection of CMV DNA by DNA amplification techniques via the polymerase chain reaction (PCR) or DNA hybridization techniques. Culture, however, maintains a slight advantage over PCR in terms of specificity.
CMV is the largest and most complex member of the Herpesviridae family of DNA viruses. The genome is composed of a linear double-stranded DNA, approximately 240 kilobases in size (150xl0 daltons), and is capable of isomer-ization. The genome has been completely sequenced and shown to contain non-overlapping open-reading frames for more than 200 potentially immunologic proteins. The genome is surrounded by an icosahedral capsid composed of 162 capsomeres. The capsid is surrounded by a poorly defined amorphous tegment which is itself surrounded by lipid envelope, givÂing the complete and mature viral particle a diameter of about 200 n. The virus lacks the enzyme thymidine kinase, which renders it resistant to those antiviral agents that depend on this enzyme for their action.
CONGENITAL CYTOMEGALOVIRUS INFECTION
2 Feb2010
Cytomegalovirus (CMV) infection is the most frequent congenital infection worldwide and is diverse in its clinical manifestations. The fetus can be infected by either a newly acquired (primary) maternal infection or a recurrent (reactivated) maternal infection. The likelihood of fetal infection and the risk of associated damage and sequelae is higher after a primary infection. Read the rest of this entry »
The optimal management of clinically localized prostate cancer remains controversial. The technique of ultrasound-guided transperineal radioactive seed implants has rapidly gained popularity in the treatment of early-stage prostate cancer with a five-year disease-specific survival of 90%. This methodology has several potential advantages to external beam radiotherapy or other implantation techniques, such as (1) pre-treatment planning; (2) precision of seed placement; (3) higher total dose to the prostate; (4) the ability to place seeds in the periprostatic region; (5) outpatient treatment; (6) low morbidity; and (7) preliminary PSA progression-free survival rates equal or superior to external beam irradiation and radical prostatectomy. It remains to be seen whether the long-term (15-year) results are as encouraging. RTOG 9805 is a multi-institutional phase II trial that will help clarify the indications and role of this popular treatment option. There has been such an increase in the utilization of these procedures that by the year 2005, it is expected that one-third of all prostate cancer patients with organ confined disease will be treated by brachytherapy only (2000-2001 ACR Standards for Radiation Oncology).
- In: Cancer
- Tags: Cancer, innovation, radiation therapy, technological advances
RADIATION MEDICINE INNOVATIONS FOR THE NEW MILLENIUM: INTENSITY-MODULATED RADIATION THERAPY
29 Jan2010
Intensity-modulated radiation therapy (IMRT) is a revolutionary new technology in the planning and delivery of external radiation. This methodology varies the intensity of the radiation beam across the treatment field, enabling the radiation oncologist to deliver high doses of radiation to volumes that tightly conform to irregular tumor geometries. Nearby, normal structures benefit from less exposure, therefore, resulting in less toxicity.
- In: Cancer
- Tags: Cancer, innovation, radiation therapy, technological advances
Stereotactic radiosurgery (SRS) is a specialized application of 3-D conformal treatment planning for treatment of an assortment of brain tumors and arteriovenous malformations. The technique delivers a high dose with millimeter tolerances, with a sharp dose gradient. Dr. Lars Leksell, from the Karolinska Institute in Stockholm, Sweden, first described SRS in 1949. However, practice of the technique did not experience explosive growth until the 1980s. SRS can be accomplished using one of three radiation modalities—gamma knife, linear accelerator (LINAC), or heavy particles such as protons.
- In: Cancer
- Tags: Cancer, innovation, radiation therapy, technological advances