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

Stressed out? Try this multiple-choice quiz:

How many antibodies can one B cell churn out per second? (a) 1, (b) 2, (c) 10, (d) 100, (e) 1,000, (f) 2,000, (g) a million.

If you guessed (f) you were right on the money. A single B lymphocyte can secrete 2,000 monoclonal antibodies into the bloodstream in a single second. But it isn't easy for that molecule. Immune system cells get stressed out, too. Generating that lightning production pace involves the B cell in a stressful avalanche of genes and proteins that make the 2,000-per-second proliferation happen. (B cells are the humoral arm of the mammalian immune defenses, which manufacture antibodies against invading antigens.)

Here's an abridged rundown of that dizzying process: Sensing an intruding infectious bacterium, say, the immune defenses dispatch a battalion of cytokines - such as interleukin-4 and -6 - to engage the enemy. "It turns out that the B cells need to be stressed," observed research immunologist Neal Iwakoshi at the Harvard School of Public Health in Boston. "That cellular cell response," he added, "which we call UPR - unfolding protein response - causes the terminal differentiation of B lymphocytes, turning them into antibody-producing plasma cells, the action site for generating antibodies to fight infection."

Iwakoshi is first author of a paper in Nature, released online March 3, 2003. The paper is titled: "Plasma cell differentiation and the unfolding protein response intersect at the transcription factor XBP-1." Its senior author is molecular immunologist Laurie Glimcher at Harvard Medical School.

"Plasma cells," explained Glimcher, "are antibody factories capable of synthesizing and secreting vast amounts of specific antibodies into the bloodstream. However, precursors of these cells need to be alerted to increase their production capacity. Our Nature article shows that B cells make small amounts of antibody, but these molecules fail to fold properly and signal the stress response. During this same split second, B cells increase their expression of the XBP-1 gene, which is the master switch for plasma cell differentiation. However, the form of XBP-1 message produced in the absence of the stress response triggers a nonfunctional protein.

"Our new data," she continued, "reports how this stress response triggers splicing [activating] of the message to encode its functional form. This then turns on genes required for plasma cell differentiation and increased antibody production. Thus, aberrant activation of XBP-1 might contribute to the development of multiple myeloma - the malignant counterpart of plasma cells."

Malignant myeloma is a relatively uncommon blood dyscrasia of unusual comportment. It afflicts roughly two to three individuals per 100,000, with males outnumbering females three to two. It occurs when plasma cells turn malignant and give rise to plasmacytomas - cancerous tumors. These punch perforations in skeletal bones - in particular, pelvis, spine, ribs and skull. This osteoporosis brings on severe pain, especially in the back and chest, plus kidney failure and recurrent bacterial infections. With medical treatment, more than half of multiple myeloma patients show improvement, though survival averages 2.5 to three years.

Mortality In Frail Old Age Is Predictable From Inflammatory Interleukin-6, Dimeric Molecules

Frailty in the elderly - decrease in function, increase in vulnerability - can ultimately lead to foreseeable death from old age. By measuring two markers of inflammation and coagulation, researchers hope they will be able to predict losses in frailty functioning and eventual mortality among superannuated patients.

In the American Journal of Medicine, released online March 7, 2003, scientists from the Duke University Medical Center in Durham, N.C., measured levels of interleukin-6 in the bloodstream as a marker of inflammation, together with a compound called D-dimer (double-molecule) as an indicator of coagulation processes. Their report bears the title: "Coagulation and inflammatory pathway activation in the development of functional decline and mortality in the elderly." The study enrolled 4,162 participants aged 65 or older in 1986, selected by a random household sampling in the Durham area. In 1992, at the sixth annual contact, blood samples reflecting IL-6 and D-dimer levels were obtained from 1,723 subjects.

"The results of the current study," the journal article concluded, "indicate that higher levels of D-dimer, and to a lesser extent, IL-6, are associated with greater functional decline and mortality. These effects are independent of age, sex, race, smoking, body mass index, health status and initial functional studies."

Hafnium, Least Sociable Of Metals, Binds Bug In Initial Step Toward Geochemical Processing

Like humans, many bacteria need to obtain essential iron from the environment. But unlike humans, these microorganisms have to take the metal in the form that Nature provides it, often as insoluble minerals. Among the least accommodating element is hafnium, a refractory metal that's mined together with zirconium; both are virtually inseparable.

Powdered hafnium is toxic by inhalation and spontaneously explosive, wet or dry. Besides light bulb filaments and electrodes, hafnium does duty as control rods in water-cooled nuclear reactors. A paper in the March 2003 issue of Nature Structural Biology, released online Feb. 24, 2003, introduces hafnium to another gig - helping bacteria dig for ferric iron. Its title: "A novel protein-mineral interface." The paper's co-authors are chemists and cell biologists at the University of Edinburgh in Scotland.

Hafnium has some properties similar to iron. Its crystal structure reveals that the hafnium ions are organized in a cluster "bridged" by oxygen atoms. The paper reports that these clusters readily bind the gonorrhea pathogen, Neisseria gonorrhoeae. "This first high-resolution structure of a protein-mineral interface," the article concludes, "suggests a novel metal-uptake mechanism and provides a model for protein-mediated mineralization-dissimilation, which plays a critical role in geochemical processes."