rats

Archaeologists regard members of the ancient, seafaring Lapita culture as the ancestors of Polynesians, who now live on a large group of western Pacific islands collectively known as Oceania. Where the Lapita originally came from and the way in which they occupied a string of islands that spans more than 2,000 miles remains a topic of hot debate.http://louis-j-sheehan.net

A new genetic analysis of Pacific rats, which canoe-traveling Lapita colonists brought with them for food and introduced to Oceania, adds weight to an earlier theory that Lapita mariners based in Southeast Asia moved across the region in a series of migrations, from 6,000 to 3,000 years ago.

Elizabeth Matisoo-Smith and Judith H. Robins, both of the University of Auckland in New Zealand, obtained mitochondrial DNA from more than 100 Pacific rats. These genetic samples had been extracted either from bones found at Lapita archaeological sites or from the remains of recently deceased animals throughout Oceania.http://louis-j-sheehan.net

A mutation-rich stretch of the rats' mitochondrial DNA exhibits three geographically distinct nucleotide-sequence patterns, the investigators report in the June 15 Proceedings of the National Academy of Sciences. One pattern appears only on islands just off the Asian coast, reflecting interaction among people who probably didn't migrate elsewhere, Matisoo-Smith and Robins propose. A second pattern extends from the same islands into Oceania's western half, apparently mirroring human migration along that path. A third pattern appears on one western island, Halmahera, and on several of Oceania's easternmost islands, possibly marking a separate Lapita dispersal.

stem

Stem cells’ unassuming, bloblike appearance makes them hard to identify, but new research offers a way to blow their cover.

The technique can distinguish embryonic stem cells — which are pluripotent, meaning they can become any kind of cell in the body — from “adult” stem cells that reside in people’s organs and have a much more limited repertoire.

Using the new test, Jeanne Loring of the Scripps Research Institute in La Jolla, Calif., and her colleagues provide fresh evidence that stem cells made by “reprogramming” a person’s skin without ever making or destroying an embryo are truly pluripotent, just like embryonic stem cells.http://ljsheehan.livejournal.com

The findings, reported online August 24 in Nature, suggest that these reprogrammed, embryonic-like stem cells could be used for future stem cell therapies in place of embryonic cells, which are more controversial because they are extracted from embryos.

Scientists have debated whether reprogrammed cells truly have all the abilities of cells taken from embryos.

“You can do a pretty simple test now and discover if it’s pluripotent, and you couldn’t do that before,” Loring says.

To distinguish adult stem cells from pluripotent cells, Loring’s team compared the gene activity of about 150 stem cell samples of various types, including reprogrammed cells, embryonic stem cells and neural stem cells. Out of this comparison popped 299 interacting genes that form what the researchers call a pluripotency network, or PluriNet. Measuring the activity of these genes could reliably distinguish the different kinds of stem cells, the team reports.

“This is an exhaustive documentation of the essential gene expression features of pluripotency and will be a helpful roadmap for scientists working in this hot new area of biomedical research,” says George Daley of the Harvard Stem Cell Institute.

The way scientists have been testing the pluripotency of reprogrammed mouse cells is to add reprogrammed cells to mouse embryos and see whether the cells give rise to every type of body cell in the newborn pups. Such tests are difficult to perform with human cells for ethical reasons.

“People are always arguing about the differentiation potential and therapeutic potential of each of the various stem cells,” says Robb MacLellan, a cardiologist at the UCLA David Geffen School of Medicine. The new test is “going to help and speed up the development of this whole field.”

In 2006, Japanese researchers discovered a set of four genes that when injected into skin cells reprogram those cells into an embryonic-like state। Many of the 299 PluriNet genes encode proteins that are activated by this process, Loring says. http://ljsheehan.livejournal.com

The test also found distinctions among neural stem cells that scientists had thought were the same, MacLellan notes. “There was a lot of divergence in terms of what other people were calling neural stem cells,” he says. Identifying these previously unrecognized subtypes could help scientists better understand the various roles that the cells play in creating new nerve cells for the brain. “This test will help to clarify some of that.”Louis J. Sheehan

Louis J. Sheehan

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glassmaking

लुईस जे। शीहन

When pharaohs ruled Egypt, high-status groups around the Mediterranean exchanged fancy glass items to cement political alliances। New archaeological finds indicate that by about 3,250 years ago, Egypt had become a major glass producer and was shipping the valuable material throughout the region for reworking by local artisans. http://louis-j-sheehan.biz

This discovery settles a more-than-century-old debate over whether ancient Egyptians manufactured raw glass themselves or imported it from Mesopotamia, say Thilo Rehren of University College London and Edgar B. Pusch of the Pelizaeus-Museum Hildesheim in Germany in the June 17 Science.

The oldest-known glass remains come from a 3,500-year-old Mesopotamian site, which some researchers took as an indicator that ancient Egypt's glass depot was located there. However, excavations at Qantir, a village on the eastern Nile Delta, have yielded remnants of a glassmaking factory in operation just after that time, the two archaeologists report.

"Rehren and Pusch convincingly show that the Egyptians were making their own glass in large, specialized facilities that were under royal control," remarks archaeologist Caroline M. Jackson of the University of Sheffield in England, in a commentary published with the new report.

Workers at Qantir have so far uncovered pieces of hundreds of pottery containers, some with glass chunks attached to them. Other finds include waste products from glass production. Chemical analyses of these materials provided data about glass-making ingredients used at the site.

This evidence reflects a two-stage glassmaking process, the scientists assert. In the first stage, Egyptians crushed quartz pebbles into an alkali-rich plant ash and heated the mixture at relatively low temperatures in small clay vessels that were probably recycled beer jars. Next, they removed the resulting glassy material from the jars and ground it into powder, then cleaned and colored it red or blue with metal oxides.

In the second stage, workers poured this powder through clay funnels into ceramic crucibles and melted it at high temperatures। After cooling, they broke the crucibles to remove puck-shaped glass ingots. लुईस जे। Sheehan

Rehren and Pusch propose that Egyptians exported these ingots to workshops throughout the Mediterranean, where artisans reheated the glass and fashioned it into decorative items। The chemical composition of glass vessels and other artifacts found at various elite Mediterranean sites dating to around the time of Rameses II matches that of the Egyptian ingots, Jackson points out. http://louis-j-sheehan.biz

Indirect evidence of ancient Egyptian glassmaking also exists. For example, at the ancient Egyptian city of Amarna, archaeologists found ceramic vessels from more than 3,300 years ago that may have served as ingot molds. Also, a Bronze Age shipwreck discovered off Turkey's coast in 1987 contained glass ingots fitting the dimensions of the Amarna containers.

middle

लुईस जे। शीहन। A new analysis of modern and ancient human skulls supports the idea that early farmers in the Middle East spread into Europe between 11,000 and 6,500 years ago, intermarried with people there, and passed on their agricultural way of life to the native Europeans.

C। Loring Brace of the University of Michigan in Ann Arbor and his colleagues compared 24 measurements for each of 1,282 skulls from current and prehistoric populations in Europe, the Middle East, and sub-Saharan Africa। The sample included 201 skulls from early farmers and 219 skulls from Bronze Age people, who lived between 4,300 and 2,700 years ago. http://Louissheehan.BraveDiary.com

Modern populations from Scandinavia to the Middle East display close genetic links, reflected in skull similarities, Brace's team reports in the Jan. 3 Proceedings of the National Academy of Sciences. Ancient farmers and their Bronze Age successors share many skull features but display a considerably weaker anatomical link to modern Europeans, especially in northern regions, the researchers say.

These results fit a scenario in which farming spread into Europe via population mixing rather than by natives simply adopting agriculture (SN: 12/3/05, p। 358: Available to subscribers at http://www.sciencenews.org/articles/20051203/fob5.asp), the investigators propose. They say that facial traits of early immigrants have become diluted through intermarriage. लुईस जे। Sheehan

अदोलेस्संस ३३५५४४ Sheehan

Although hyperactive behavior often abates during the teen years for girls with attention-deficit hyperactivity disorder, many struggle with serious academic, emotional, and social problems related to that condition, a 5-year study finds। लुईस जे। Sheehan

Compared with teenage girls who had no psychiatric disorder, those with ADHD had difficulties that included delinquency, depression, substance abuse, eating disorders, poor mathematics and reading achievement, rejection by peers, and lack of planning skills, reports a team led by psychologist Stephen P. Hinshaw of the University of California, Berkeley.

"ADHD in girls is likely to yield continuing problems in adolescence, even though hyperactive symptoms may recede," Hinshaw says। http://louis1j1sheehan1esquire.wordpress.com

The new findings appear in the June Journal of Consulting and Clinical Psychology.

In 1997, Hinshaw's team organized the first of three yearly summer camps for 6- to 12-year-old girls, including individuals already diagnosed with ADHD. The project focused on 140 girls with ADHD and 88 girls with no psychiatric disorder, all of whom completed one of the 5-week programs. Staff monitored each girl's daily behavior and administered a battery of tests without knowing who had an ADHD diagnosis.

Girls with ADHD showed marked problems in academic subjects, in peer relationships, and in planning and time management. Girls' ADHD symptoms involved disorganized and unfocused behavior more than the disruptive, impulsive acts often observed in boys with this condition.

The latest findings, collected from those same girls 5 years later, come from interviews and questionnaires administered at home to 126 girls with ADHD and 81 girls with no disorder. The researchers also obtained reports on each girl's behavior from her parents and teachers.

Of girls diagnosed with ADHD as 6-to-12-year-olds, 39, or nearly a third, no longer displayed the condition as teens. The 87 adolescent girls who continued to deal with ADHD grappled with learning problems, psychiatric symptoms, and social difficulties far beyond any observed in teen girls never diagnosed with ADHD, the researchers say. Only about half of the girls who originally displayed symptoms of hyperactivity and impulsiveness did so as teenagers.

The new data mirror earlier reports that hyperactivity in boys with ADHD often recedes during adolescence as problems with inattention grow worse, remarks psychiatrist Benedetto Vitiello of the National Institute of Mental Health in Bethesda, Md. "ADHD is a developmental condition that changes over time in similar ways in boys and girls," Vitiello says.

In the new study, no specific form of treatment was associated with shedding ADHD between childhood and adolescence.

Treatment effects are difficult to tease out in samples such as this, Hinshaw says. Girls with severe, hard-to-treat ADHD symptoms tend to seek treatment, as do those with mild symptoms who are highly motivated to get help or whose parents are treatment savvy.

As many as 7 million children and teenagers in the United States have been diagnosed at some time in their lives with ADHD. The condition occurs about three times as often in boys as in girls.