Spatially resolved detection of attomole quantities of organic molecules localized in picoliter vials using time-of-flight secondary ion mass spectrometry.

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) has been utilized to detect femtomole and attomole quantities of organic species from within silicon nanovials. By using high-density arrays (10,000 nanovials/cm2) it is possible to chemically characterize diverse sample sets within a single chemical image. Molecular sensitivities, for the compounds investigated, very between 85 attomoles and 25 femtomoles, and typical acquisition times are approximately 100 ms per nanovial. These vials are fabricated using photolithography and KOH etching of Si[001] wafers to create wells, with a pyramidal cross section, ranging in size from 25 to 5625 micron 2. The volume ranges from 30 femtoliters to 100 picoliters, respectively. A drawn glass microinjector and solenoid-driven dispenser are utilized to array picoliter volumes of organic compounds into individual silicon nanovials. Solution concentrations typically range from 1 x 10(-2) to 1 x 10(-4) M allowing femtomole and even attomole quantities of material to be dispensed into each vial.

The Falmouth Safe Skin Project: evaluation of a community program to promote sun protection in youth.

A multidimensional community-based skin cancer prevention program was conducted in Falmouth, Massachusetts, combining community activism with publicity campaigns and behavioral interventions to improve sun protection knowledge; attitudes; and practices in parents, caregivers, and children. The program was associated with improvements in target outcomes, based on two telephone surveys of random samples of parents (n = 401, 404). After program implementation, fewer parents reported sunburning of their children, particularly among children 6 years old or younger (18.6% in 1994 vs. 3.2% in 1997), and more parents reported children using sunscreen, particularly continuous use at the beach (from 47.4% to 69.9% in younger children). Hat and shirt use did not increase. Improvements also were seen in parent role modeling of sun protection practices, parents' self-efficacy in protecting children from the sun, and sun protection knowledge. While these findings must be interpreted cautiously, they do suggest that this project was effective in promoting sun protection.

Physiologic amputation prevents myoglobinuria from lower extremity myonecrosis.

Myoglobinuria secondary to myonecrosis is a proven cause of renal failure, especially in critically ill patients. Physiologic amputation or cryoamputation has been used at our institution for the past two decades as a safe and effective treatment for lower extremity infection, intractable rest pain, and irreversible myonecrosis. We retrospectively studied five critically ill patients with myonecrosis of lower extremities associated with myoglobinuria. The etiology of myonecrosis included preexisting peripheral vascular disease or crush injury to the lower extremities. It was determined that all five patients were too ill to undergo emergency amputation. Myoglobinuria was documented in all five patients and cleared within 24 hours of physiologic amputation in four patients. All five patients had elevated creatine phosphokinase levels (mean 20,270 mU/mL, range 12,090 to 43,164 mU/mL) that significantly decreased within 48 hours of physiologic amputation (mean 6,488 mU/mL, range 2,250 to 13,580 mU/mL). Mechanical ventilation and cardiovascular support were required in four patients. All patients had transient episodes of renal insufficiency with two progressing to anuric renal failure and requiring dialysis. One patient's renal failure resolved after 56 days, but the other patient died of a cerebrovascular accident 22 days after initiation of physiologic amputation. The mean duration of physiologic amputation was 15.6 days (range 5 to 32 days) with no significant complication due to physiologic amputation. All five patients had surgical amputation successfully. Three patients survived. The two deaths in the study were due to a cerebrovascular accident in one patient and a cardiopulmonary arrest in another. Physiologic amputation is a treatment option that halts myonecrosis, prevents myoglobinuria, and lessens the risk of associated acute renal failure. Physiologic amputation may be appropriately used in patients with myoglobinuria due to extremity myonecrosis who are deemed too critically ill to survive emergency amputation.

Analyses of cryogenic samples using ion-induced desorption and multiphoton resonance ionization.

In this study, ion-beam-induced desorption with multiphoton resonance ionization detection of desorbed neutral molecules is used to characterize frozen aqueous solutions. This type of matrix is of particular importance since it serves as a model for biological matrices. The time-of-flight mass spectrum, obtained in this way for a millimolar tryptophan/H2O solution, is virtually identical to that for a submonolayer of tryptophan on a silicon wafer. The tryptophan signal from a frozen solution is demonstrated to have a linear dependence on concentration by using 4,4'-biphenyldiol as an internal standard. A detection limit of 2 x 10(-6) M is also demonstrated. Since our ion beam samples one layer of 0.1 cm2 and we assume 10(15) molecules/cm2 of ice, this concentration corresponds to approximately 4 x 10(6) molecules/layer. It is also shown that the signal exhibits an exponential decay with primary ion dose due to the accumulation of primary ion damage in the near-surface molecules.

Current role of cryoamputation.

Cryoamputation or physiologic amputation has been used at our institution for more than 30 years. From 1971 through 1989, 891 major lower extremity amputations were performed in 750 patients. With the use of dry ice or mechanical refrigeration, 320 (36%) physiologic amputations were performed in 292 patients. After physiologic amputation, the initially elevated white blood cell count and temperature decreased. Complications of physiologic amputation were unusual; 3% of patients developed minor freezing above the tourniquet, which did not alter the amputation level, while 1% had purulence at the level of surgical amputation that required delayed stump closure. The overall operative mortality rate in patients who underwent physiologic amputation was 11%, which was equivalent to the rate in patients undergoing primary amputation. Revision was required in 9% of amputations after preliminary physiologic amputation compared with 17% of primary amputations. Physiologic amputation is a simple technique, controls local infection, avoids emergency surgery, and allows for medical stabilization prior to surgery. Amputation revision after physiologic amputation is required less often than after primary amputation, while the mortality rate is comparable to that of patients undergoing primary amputation.

Detection of biomolecules on surfaces using ion-beam-induced desorption and multiphoton resonance ionization.

Multiphoton resonance ionization (MPRI) has been combined with ion-beam-induced desorption to examine a set of thermally labile biological molecules present on surfaces. Specifically, we have examined films of adenine and beta-estradiol, molecules with a rigid skeletal backbone. In both of these cases, molecular ions could be produced efficiently without cooling the neutral molecules into their ground vibrational state. We have also studied other more fragile molecules such as tryptamine, tryptophan, phenylalanine, and serotonin. The base peak in the mass spectra of these molecules is fragment ions formed by losses of the amine side chains. Even with this fragmentation, however, it is possible to achieve sensitivity limits that are many orders of magnitude greater than for secondary ion mass spectrometry, without preparing the samples in special matrices. For serotonin, detection limits of 40 fmol on the surface of a silicon target are achievable. The results also yield a linear relation between the serotonin base fragment ion intensity and the known surface concentration.

Influence of solar heating and precipitation scavenging on the simulated lifetime of post--nuclear war smoke.

The behavior of smoke injected into the atmosphere by massive fires that might follow a nuclear war was simulated. Studies with a three-dimensional global atmospheric circulation model showed that heating of the smoke by sunlight would be important and might produce several effects that would decrease the efficiency with which precipitation removes smoke from the atmosphere. The heating gives rise to vertical motions that carry smoke well above the original injection height. Heating of the smoke also causes the tropopause, which is initially above the smoke, to reform below the heated smoke layer. Smoke above the tropopause is physically isolated from precipitation below. Consequently, the atmospheric residence time of the remaining smoke is greatly increased over the prescribed residence times used in previous models of nuclear winter.