Editor's note: Science Scan is a roundup of recently published biotechnology-relevant research.

The majority of cloned mammals derived by nuclear transfer die during gestation. The very cloning process jeopardizes the integrity of an animal's entire genome. Scientists have predicted this danger by analyzing a mere dozen genes. A current study that surveyed 12,654 genes is reported in the Proceedings of the National Academy of Sciences (PNAS), released online Sept. 10, 2002, under the title: "Abnormal gene expression in cloned mice derived from ES [embryonic stem] cell and cumulus cell nuclei." The paper's senior author is embryologist and molecular biologist Rudolf Jaenisch at the Whitehead Institute for Biomedical Research in Cambridge, Mass.

Using DNA arrays, he and his co-authors found that approximately one in every 25 genes was abnormally expressed in placentas and livers from cloned mice. "Recent studies showing premature death, pneumonia, liver failure and obesity in aging cloned mice," Jaenisch said, "could be a consequence of these gene expression abnormalities." He added, "This study establishes unequivocally that the normalcy of surviving cloned animals should not be based on superficial clinical examinations, but rather on detailed molecular analysis of tissues from adult cloned animals. Even seemingly normal-looking' clones may have serious underlying genome defects. Thus," Jaenisch cautioned, "cloning for the purpose of producing another human being is completely unsafe and unethical.

"The cloning procedure, however," he noted, "can be safely used to create embryonic stem cells to treat diseases such as Alzheimer's and diabetes [along with] autoimmune diseases. The procedure, often called therapeutic cloning,' involves removing the nucleus, which contains the DNA, from an egg and replacing it with the nucleus from an adult. For instance, the nucleus from the skin cell of an Alzheimer's patient can be transferred into an empty egg. The egg resets the developmental clock of the transferred nucleus, and the reprogrammed cell starts developing into an embryo that is practically identical to the patient.

"At the stage when the embryo develops into a blastocyst - a hollow ball of approximately 100 cells - it contains a nub composed of embryonic stem cells that have the potential to become any cell in the body, including new neurons, muscle cells and blood cells. The ES cells from the blastocyst," Jaenisch pointed out, "can be isolated and used to treat the patient without the complications associated with foreign donor tissue."

Earlier this year, he and his co-authors used a mouse model to establish for the first time that a combination of therapeutic cloning, gene therapy and embryonic stem cell differentiation could be used to create custom-tailored cellular therapies for genetic disorders. (See BioWorld Today, Feb. 13, 2002, p. 1.)

International Clinical Trial Of Ovarian Cancer Drugs Scored Carboplatin As Least Toxic

Ovarian cancer is the second commonest form of gynecological cancer in the Western nations, with worldwide prevalence of 150,000. It accounts for 5 percent of all cancer deaths. In the U.S., about 25,000 women are diagnosed with ovarian cancer each year. Annually in the UK, there are nearly 6,000 new cases and 4,500 deaths. For patients with advanced disease, overall five-year survival is 30 percent. The Lancet Oncology, dated Sept. 3, 2002, carries an article titled: "Chemotherapy for epithelial ovarian cancer - treatment at first diagnosis." It reports the results of an international study, which suggests that carboplatin could be the first-line chemotherapy drug for ovarian cancer. Its authors are oncologists at the University of Sydney in Australia. The study found that carboplatin has no overall survival benefit compared with other chemotherapeutic drugs, but is less toxic.

The controlled clinical trial enrolled 2,074 women with ovarian cancer from 130 centers in eight countries. They were randomly assigned carboplatin plus paclitaxel or control. Average follow-up was just over four years. Those given the two-drug chemotherapy had more serious side effects - alopecia, fever and sensory neuropathy in the skin. "The results," observed an editorial, "suggest that single-agent carboplatin and paxlitaxel plus carboplatin are all safe and show similar effectiveness as first-line treatments. Of these three regimens, carboplatin may be regarded as the preferred treatment because of its better toxicity profile."

Gecko Lizard's Hair-Raising Defiance Of Gravity Duplicated By Dry Synthetic Toe-Gripping Fibrils

How does the gecko do it? Travelers to tropical climates (including South Florida) are often amazed by the ability of these inch-long, half-gram lizards to skitter up smooth walls, glide along glass windowpanes and traverse ceilings. Now a research team at the University of California at Berkeley has proved that gecko lizards' toes cling by virtue of simple molecular forces known as van der Waals bonds. Named after the Dutch physicist Johannes Diderik van der Waals (1837-1923), these bonds are temporary rearrangements of electrons that create an electrodynamic attraction between the gecko's toes and the surface it is climbing.

The UC/Berkeley scientists report their experimental proof in the Proceedings of the National Academy of Sciences (PNAS) released online Aug. 27, 2002. The paper's title: "Evidence for van der Waals adhesion by gecko setae." Setae are stiff hairs or bristles. Millions of them, split and re-split, line the gecko's own feet. The PNAS co-authors discovered the mini-lizards' ability to stick by synthesizing the critters' setae. Their nano-scale, artificial hair tips, though rudimentary, worked nearly as well as nature's own reptilian setae. "This is the first step - the pathway - to synthesizing the first self-cleaning dry adhesive," observed the article's senior author, integrative biologist Robert Full.

"Such an adhesive," he added, "would have many uses, such as moving semiconductors around in a vacuum chamber, and could stick to surfaces under water or in space." The team's experiment was funded by grants from the U.S. federal government's Defense Advanced Research Projects Agency.