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PubMed1992

Responsiveness to laboratory pain in women as a function of age and childbirth pain experience.

Pain responsiveness was investigated experimentally as a function of age and childbirth pain experience. Sensitivity to cold pressor-induced pain was assessed through threshold, tolerance, and visual analog pain ratings. It was hypothesized that childbirth pain experience would mostly modify experimental pain judgment, in accordance with the adaptation-levels model. That is, childbirth pain would be used as an "anchor" in evaluating other painful events. Fifteen parous women were compared to 12 nulliparous women of the same age (mean age: 35 years) as well as to 15 nulliparous younger women (mean age: 24 years). This comparison was undertaken in order to distinguish the effects of age, which was found to correlate with pain threshold. Analysis of variance comparing the three groups of women was performed on each of the three cold pressor measures. A significant effect was found for pain threshold. Multiple comparisons indicated that parous women had a higher pain threshold than both groups of nulliparous women which did not differ from one another. Thus, painful childbirth experience is sufficient to raise cold pressor pain threshold. This finding has never before been reported in the pain literature. It is consistent with anecdotal reports from parous women who, when providing cold pressor pain judgments, say that "nothing compares to labor pain."

Adolescent↗
PubMed2004

Infrared video thermography: a technique for assessing cold adaptation in insects.

Insects can survive subzero temperatures by two main strategies: freeze tolerance and freeze avoidance. An array of techniques have been used to investigate the physiological limits of insects to low temperatures, such as differential scanning calorimetry, temperature-controlled cooling apparatus, thermocouples, and computer-controlled chart recording equipment. However, these techniques require animals to be stationary, precluding behavioral data. We used infrared video thermography to investigate cold adaptation in an alpine insect, expanding such investigations to include behavioral response as an indicator of physiological stress. This technique is noninvasive and provides a large amount of physiological information, such as supercooling points, lower lethal temperatures, and hemolymph melting points. Insect supercooling points in response to a constant cooling rate were variable; however, temperatures at the initiation of behavioral stress response were less variable. Assessments of supercooling points and lower lethal temperatures obtained in this way are more biologically meaningful because allowing unhindered movement of insects more closely resembles natural environments.

Adaptation, Physiological↗
PubMed1989

Seventy-two-hour preservation of the canine pancreas by the two-layer (Euro-Collins' solution/perfluorochemical) cold storage method.

A 72-hr preservation of canine pancreas by a 2-layer (Euro-Collins'/Perfluorochemical) cold storage method was tested in the canine model of segmental pancreas autotransplantation. The functional recovery of the grafts by this method (group 1) was determined by daily fasting blood glucose concentration and intravenous glucose tolerance test at 2 weeks after autotransplantation and compared with simple cold storage with Euro-Collins' solution (group 2) and control (no preservation) (group 3). Maintenance of normoglycemia for at least 5 days after transplantation was considered a successful preservation. The functional success rates after 72-hr preservation were 100%, 0%, and 100% for groups 1, 2, and 3, respectively. The mean K values of group 1 after 72-hr preservation was 1.78 +/- 0.42 compared with 2.05 +/- 0.32 for group 3 at 2 weeks after transplantation. Biopsies of grafts of group 2 after 72-hr preservation showed remarkable autolytic changes in exocrine and endocrine tissues. In contrast, biopsies of grafts of group 1 after 72-hr preservation showed almost normal architecture in both tissues. In addition, biopsies of 72-hr preserved grafts of group 1 at 4 weeks after after autotransplantation showed almost normal pancreas architecture with minimal fibrotic changes in the exocrine tissue. This study demonstrated the possibility of 72-hr preservation of the pancreas for transplantation.

Animals↗
PubMed2004

Ethosuximide reverses paclitaxel- and vincristine-induced painful peripheral neuropathy.

Paclitaxel (Taxol) is one of the most effective and frequently used chemotherapeutics for the treatment of solid tumours. However, paclitaxel produces peripheral neurotoxicity with patients reporting sensory abnormalities and neuropathic pain during and often persisting after paclitaxel therapy. The mechanisms underlying this dose-limiting side effect are currently unknown and there are no validated drugs for its prevention or control. Male Sprague-Dawley rats received four intraperitoneal (i.p.) injections on alternate days of 2 mg/kg paclitaxel. Behavioural assessment using von Frey filaments and acetone showed that such paclitaxel treatment induced a pronounced mechanical and cold allodynia/hyperalgesia. Thus these studies aim to test potential analgesics on established paclitaxel-induced pain. Paclitaxel-induced pain appears to be relatively resistant to opioid therapy i.p. 4 mg/kg morphine was ineffective and i.p. 8 mg/kg morphine only elicited up to a 50% reversal of mechanical allodynia/hyperalgesia. Interestingly, a maximally tolerated dose (i.p. 0.2 mg/kg) of the potent NMDA receptor antagonist MK-801 produced no significant reversal of the mechanical allodynia/hyperalgesia suggesting that NMDA receptors have little role in paclitaxel-induced pain. Ethosuximide (i.p. 450 mg/kg) an anti-epileptic and relatively selective T-type calcium channel blocker elicited a near complete reversal of mechanical allodynia/hyperalgesia. Repetitive dosing with ethosuximide (i.p. 100 or 300 mg/kg daily for 3 days) showed a dose-related consistent reversal of mechanical allodynia/hyperalgesia with no evidence of tolerance. Ethosuximide (i.p. 300 mg/kg) also reversed paclitaxel-induced cold allodynia and vincristine-induced mechanical allodynia/hyperalgesia. These data suggest that T-type calcium channels may play a role in chemotherapy-induced neuropathy and moreover identify ethosuximide as a new potential treatment for chemotherapy-induced pain.

Animals↗
PubMed1986

The effects of cigarette smoking on the perception of electrical stimulation and cold pressor pain.

Prior research has attempted to delineate the effects of cigarette smoking on pain. However, there has been little consensus among findings. Therefore, the present investigation was designed to provide a more carefully controlled evaluation of the effects of cigarette smoking on pain. Specifically, the effects of cigarette smoking on two pain tasks (electrical stimulation and cold pressor) were assessed via three primary response measures: pain threshold, pain tolerance and McGill Pain Questionnaire scores. The results of this study indicated that cigarette smoking did not affect subsequent ratings on any of the response measures for either cold pressor or electrical stimulation tasks. These data are integrated with those of previous research and hypotheses are proposed regarding specific factors responsible for the conflicting findings of studies.

Adolescent↗
PubMed2001

Efficacy of inactivated and cold-adapted vaccines against influenza A infection, 1985 to 1990: the pediatric experience.

BACKGROUND: Influenza is a common and potentially serious infection in children. Although there is interest in broadening the use of influenza vaccine in healthy children, there are few large, randomized, controlled trials that evaluate the safety and efficacy of inactivated vaccine in the pediatric population. METHODS: From 1985 through 1990 a randomized, controlled trial of cold-adapted and inactivated vaccines for the prevention of influenza A disease was conducted at Vanderbilt University, and the cumulative results from this trial in patients of all ages have been previously published. We reanalyzed the data from this trial in the subset of patients who were younger than 16 years at the time of their participation. We determined vaccine safety, immunogenicity and efficacy, based on culture-positive illness and seroconversion, in this subset of patients. RESULTS: During the 5 years of the study, 791 children younger than 16 years received 1809 doses of either inactivated or cold-adapted vaccine or placebo. The vaccines were well-tolerated, and there were no serious reactions. Inactivated trivalent influenza vaccines were 91.4 and 77.3% efficacious in preventing symptomatic, culture-positive influenza A H1N1 and H3N2 illness, respectively. The efficacy of the inactivated vaccine based on hemagglutination inhibition assay seroconversion was 67.1 and 65.5%, respectively, for H1N1 and H3N2 serotypes. CONCLUSIONS: Inactivated trivalent influenza A vaccines are well-tolerated and efficacious in the prevention of influenza A disease in children 1 to 16 years old.

Adolescent↗
PubMed1997

Glucose effectiveness assessed under dynamic and steady state conditions. Comparability of uptake versus production components.

Glucose tolerance is determined by both insulin action and insulin-independent effects, or "glucose effectiveness," which includes glucose-mediated stimulation of glucose uptake (Rd) and suppression of hepatic glucose output (HGO). Despite its importance to tolerance, controversy surrounds accurate assessment of glucose effectiveness. Furthermore, the relative contributions of glucose's actions on Rd and HGO under steady state and dynamic conditions are unclear. We performed hyperglycemic clamps and intravenous glucose tolerance tests in eight normal dogs, and assessed glucose effectiveness by two independent methods. During clamps, glucose was raised to three successive 90-min hyperglycemic plateaus by variable labeled glucose infusion rate; glucose effectiveness (GE) was quantified as the slope of the dose-response relationship between steady state glucose and glucose infusion rate (GE[CLAMP(total)]), Rd (GE[CLAMP(uptake)]) or HGO (GE[CLAMP(HGO)]). During intravenous glucose tolerance tests, tritiated glucose (1.2 microCi/kg) was injected with cold glucose (0.3 g/kg); glucose and tracer dynamics were analyzed using a two-compartment model of glucose kinetics to obtain Rd and HGO components of glucose effectiveness. All experiments were performed during somatostatin inhibition of islet secretion, and basal insulin and glucagon replacement. During clamps, Rd rose from basal (2.54+/-0.20) to 3.95+/-0.54, 6.76+/-1.21, and 9.48+/-1.27 mg/min per kg during stepwise hyperglycemia; conversely, HGO declined to 2.06+/-0.17, 1.17+/-0.19, and 0.52+/-0.33 mg/min per kg. Clamp-based glucose effectiveness was 0.0451+/-0.0061, 0.0337+/-0.0060, and 0.0102+/-0.0009 dl/min per kg for GE[CLAMP(total)], GE[CLAMP(uptake)], and GE[CLAMP(HGO)], respectively. Glucose's action on Rd dominated overall glucose effectiveness (72.2+/-3.3% of total), a result virtually identical to that obtained during intravenous glucose tolerance tests (71.6+/-6.1% of total). Both methods yielded similar estimates of glucose effectiveness. These results provide strong support that glucose effectiveness can be reliably estimated, and that glucose-stimulated Rd is the dominant component during both steady state and dynamic conditions.

Animals↗
PubMed1992

Long-term preservation of canine pancreas by a new simple cold storage method using perfluorochemical--the two-layer cold storage method (Euro-Collins' solution/perfluorochemical).

Long term preservation of canine pancreas by a new simple cold storage method using perfluorochemical (PFC), two-layer (Euro-Collins' solution (EC)/PFC) cold storage method, was tested in the canine model of segmental pancreas autotransplantation. The functional recovery of the graft preserved by this method (group 1) was determined by daily fasting blood glucose concentration and intravenous glucose tolerance test at two weeks after autotransplantation and compared with simple cold storage with EC (group 2), cold storage in EC with simple bubbling of oxygen (group 3), and control (no preservation) (group 4). Maintenance of normoglycemia at least 5 days after transplantation was considered a success of preservation. The functional success rates after 24 hour preservation were 4/4 (100%), 4/4 (100%) and 4/5 (80%) for groups 1, 2 and 3 respectively, and the functional success rates of groups 1, 2 and 3 after 48 hour preservation were 5/6 (86%), 1/5 (20%) and 1/5 (20%) respectively. In addition the functional success rates after 72 hour preservation were 6/6 (100%), 0/6 (0%) and 0/5 (0%) for groups 1, 2, and 3 respectively. It was clear that the two-layer cold storage method had made it possible to preserve the canine pancreas for up to 72 hours although the upper limit of reliable preservation time of groups 2 and 3 was 24 hours. The mean K value of group 1 after 72 hour preservation was 1.78 +/- 0.42 compared with 2.05 +/- 0.32 of group 4 at two weeks after transplantation. Biopsies of grafts of group 2 and 3 after 72 hours preservation showed remarkable autolytic changes in exocrine and endocrine tissues. In contrast, biopsies of grafts of group 1 after 72 hour preservation showed almost normal architecture in both tissues. In addition, biopsies of 72 hour preserved grafts of group 1 at 4 weeks after autotransplantation showed almost normal pancreatic architecture with minimal fibrotic changes in the exocrine tissue. This study demonstrated the possibility of long-term preservation of the pancreas for transplantation.

Animals↗
PubMed2004

Thermal sensation and comfort in women exposed repeatedly to whole-body cryotherapy and winter swimming in ice-cold water.

Whole-body cryotherapy (WBC; -110 degrees C) and winter swimming (WS) in ice-cold water are severe ambient cold exposures, which are voluntarily practiced by humans in minimal clothing. The purpose was to examine thermal sensation and thermal comfort associated with WBC and WS. Twenty women similar in body mass index, age, physical activity, and use of hormonal contraception were pairwise randomized either to the WBC group or the WS group. The duration of each WBC exposure was 2 min, which was repeated three times per week for 3 months (13 weeks). Similar exposure frequency was used for the WS group, but each exposure lasted 20 s in outdoor conditions. Thermal sensation and comfort were asked with standard scales. After WBC, 65% of the thermal sensation votes were 'neutral' or 'slightly cool.' After WS, 81% of the thermal sensation votes were 'warm,' 'neutral,' or 'slightly cool.' Majority of comfort votes immediately after exposures in WBC group (98%) and in the WS group (93%) were 'comfortable' or 'slightly uncomfortable.' Thermal sensation and comfort became habituated in both groups at an early stage of trials, but the changes were less conclusive in WS group due to variable conditions outdoors. In the WBC group, cold sensation was less intense already after the second exposure. In conclusion, repeated exposures to WBC and WS in healthy women were mostly well tolerated and comfortable. The results indicate that during repeated severe whole-body cold stress of short duration, thermal sensation and comfort become habituated during the first exposures.

Adult↗
PubMed2006

Bacterial diversity in permanently cold and alkaline ikaite columns from Greenland.

Bacterial diversity in alkaline (pH 10.4) and permanently cold (4 degrees C) ikaite tufa columns from the Ikka Fjord, SW Greenland, was investigated using growth characterization of cultured bacterial isolates with Terminal-restriction fragment length polymorphism (T-RFLP) and sequence analysis of bacterial 16S rRNA gene fragments. More than 200 bacterial isolates were characterized with respect to pH and temperature tolerance, and it was shown that the majority were cold-active alkaliphiles. T-RFLP analysis revealed distinct bacterial communities in different fractions of three ikaite columns, and, along with sequence analysis, it showed the presence of rich and diverse bacterial communities. Rarefaction analysis showed that the 109 sequenced clones in the 16S rRNA gene library represented between 25 and 65% of the predicted species richness in the three ikaite columns investigated. Phylogenetic analysis of the 16S rRNA gene sequences revealed many sequences with similarity to alkaliphilic or psychrophilic bacteria, and showed that 33% of the cloned sequences and 33% of the cultured bacteria showed less than 97% sequence identity to known sequences in databases, and may therefore represent yet unknown species.

Alkalies↗
PubMed2003

Antinociceptive activity of the N-methyl-D-aspartate receptor antagonist N-(2-Indanyl)-glycinamide hydrochloride (CHF3381) in experimental models of inflammatory and neuropathic pain.

N-(2-Indanyl)-glycinamide hydrochloride (CHF3381) is a novel low-affinity, noncompetitive N-methyl-d-aspartate receptor antagonist. The current study compared the antinociceptive effects of CHF3381 with those of gabapentin and memantine in in vitro and in vivo models of pain. In isolated rat spinal cord, CHF3381 and memantine, but not gabapentin, produced similar inhibition of the wind-up phenomenon. CHF3381 suppressed the maintenance of carrageenan-induced thermal and mechanical hyperalgesia in the rat with a minimum significantly effective dose (MED) of 30 mg/kg p.o. Memantine produced a partial reversal of both thermal and mechanical hyperalgesia (MED = 10 and 15 mg/kg i.p., respectively). Gabapentin reversed mechanical hyperalgesia (MED = 10 mg/kg s.c.), but did not affect thermal hyperalgesia. In the mouse formalin test, CHF3381 and memantine preferentially inhibited the late phase (MED = 30 and 20 mg/kg i.p., respectively); gabapentin inhibited only the late phase (MED = 30 mg/kg s.c.). Unlike morphine, CHF3381 chronic administration was not accompanied by the development of tolerance in the formalin test. Furthermore, morphine tolerance did not cross-generalize to CHF3381. In rats with a sciatic nerve injury, CHF3381 relieved both cold and mechanical allodynia (MED = 100 mg/kg p.o.). In contrast, memantine was inactive. Gabapentin blocked cold allodynia (MED = 30 mg/kg s.c.), but had marginal effects on mechanical allodynia. In diabetic neuropathy, CHF3381 reversed mechanical hyperalgesia (MED = 50 mg/kg p.o.). Memantine (15 mg/kg i.p.) produced an antinociceptive effect, whereas gabapentin (100 mg/kg p.o.) had no significant effect. Thus, CHF3381 may be useful for the therapy of peripheral painful neuropathies.

Animals↗
PubMed1984

Comparison of three cognitive strategies in altering pain behaviors on a cold pressor task.

The efficacy of three cognitive strategies for coping with pain was examined in a cold-water pressor task in a sample of college students. Subjects were pretested and then randomly assigned to one of three treatment conditions (Paradoxical Intention, Rational Self-statement, or Self-observation) or to an expectancy control group. Following training in the respective cognitive strategies, all groups were given a posttest in the cold-water pressor to determine the effectiveness of the treatment. Pain thresholds, tolerances, and discomfort ratings were recorded for subjects in each condition. No differences were found between the Paradoxical Intention or Rational Self-statement groups and the Expectancy Control on any of the pain measures. The Self-observation treatment condition, however, had significantly higher pain tolerance scores than the Expectancy Control group. The findings were attributed to the subjects' dissociating the sensory aspects of the pain experience from the anxiety when focusing upon the coldness and wetness of the cold water.

Adaptation, Psychological↗
PubMed2003

Freezing sensitivity in the sfr4 mutant of Arabidopsis is due to low sugar content and is manifested by loss of osmotic responsiveness.

Protoplasts were tested to determine whether the freezing sensitivity of the sfr4 (sensitive to freezing) mutant of Arabidopsis was due to the mutant's deficiency in soluble sugars after cold acclimation. When grown under nonacclimated conditions, sfr4 protoplasts possessed freezing tolerance similar to that of wild type, with the temperature at which 50% of protoplasts are injured (LT(50)) of -4.5 degrees C. In both wild-type and sfr4 protoplasts, expansion-induced lysis was the predominant lesion between -2 degrees C and -4 degrees C, but its incidence was low (approximately 10%); below -5 degrees C, loss of osmotic responsiveness (LOR) was the predominant lesion. After cold acclimation, the LT(50) was decreased to only -5.6 degrees C for sfr4 protoplasts, compared with -9.1 degrees C for wild-type protoplasts. Although expansion-induced lysis was precluded in both types of protoplasts, the sfr4 protoplasts remained susceptible to LOR. After incubation of seedlings in Suc solution in the dark at 2 degrees C, freezing tolerance and the incidence of freeze-induced lesions in sfr4 protoplasts were examined. The freezing tolerance of isolated protoplasts (LT(50) of -9 degrees C) and the incidence of LOR were now similar for wild type and sfr4. These results indicate that the freezing sensitivity of cold-acclimated sfr4 is due to its continued susceptibility to LOR (associated with lyotropic formation of the hexagonal II phase) and associated with the low sugar content of its cells.

Acclimatization↗
PubMed2003

Dispositional anxiety and the experience of pain: gender-specific effects.

AIM OF INVESTIGATION: Increased anxiety is believed to correlate with increased pain sensitivity in men and women. However, one laboratory-based study and one clinical-based study have offered evidence to suggest that the effect of anxiety in modulating pain sensitivity is specific to men only. The aim of the present study was to examine further whether anxiety differentially effects men and women's report of experimentally induced pain. METHODS: One hundred forty-four healthy university students (75 women, 69 men) were exposed to a contact heat pain procedure (ascending method of limits procedure, baseline temperature 30 degrees C, +/- 0.2 degrees C, rate of change 2.0 degrees C/s, cut-off limit 52 degrees C) and a cold pressor pain procedure (constant temperature +1 degrees C; +/-1 degrees C, cut-off limit 240 s). RESULTS: The results agreed with the previous two studies indicating a sex-specific effect of anxiety on pain report. Male participants scoring above the median on the Trait Anxiety Inventory reported significantly greater pain intensity, unpleasantness and showed lower pain tolerance compared to males scoring below the median on the cold pressor pain procedure, while no such differences in cold pressor pain report were found between high and low anxious women. No effect of anxiety was found on measures taken from the contact heat pain procedure, indicating that the sex-specific effect of anxiety on laboratory induced pain is dependent upon the method of stimulation used. CONCLUSION: Anxiety is an important factor when considering gender differences in pain perception and warrants further investigation.

Adult↗
PubMedDate not supplied

Sex differences and incentive effects on perceptual and cardiovascular responses to cold pressor pain.

OBJECTIVE: Sex differences in pain perception have been widely reported, with women typically displaying greater pain sensitivity than men, but the mechanisms underlying these differences remain unclear. One possible explanation suggests that men are more motivated to tolerate and suppress expressions of pain because of the masculine sex role, whereas the feminine sex role encourages pain expression and produces lower motivation to tolerate pain among women. METHODS: To examine the influence of motivation on perceptual and cardiovascular responses to pain among women and men, different levels of monetary incentive (high vs. low incentive) were provided to a group of 81 healthy young adults undergoing the cold pressor pain procedure. It was anticipated that men would have greater endogenous motivation and would therefore be less affected by the external incentive. RESULTS: Men had higher pain thresholds and tolerances and lower pain ratings than women, but the incentive condition produced no significant effect on pain responses. Resting blood pressure was positively correlated with pain tolerance among the low incentive group, whereas blood pressure reactivity to the cold pressor predicted pain tolerance in the high incentive group. CONCLUSIONS: Thus, monetary incentive did not influence pain responses, but the relationship between cardiovascular measures and pain responses was influenced by the incentive manipulation. Potential explanations for the observed results are presented, and the implications for applying the biopsychosocial model to pain research are discussed.

Adult↗
PubMed1997

Expectancy variables predicting tolerance and avoidance of pain in chronic pain patients.

Previous research on anxiety and some recent reports on chronic pain suggest that the response to aversive stimuli may be influenced by expectations rather than actual experience. This study examined the contributions of four expectancy-related variables to the tolerance and avoidance of pain: pain expectancy, response expectancy, self-efficacy expectancy, and danger expectancy. Chronic pain sufferers volunteered to undergo cold pressor pain on two trials (the first for practice, and the second to determine tolerance) and then faced the prospect of a third trial (to determine avoidance). It was found that expected tolerance (or response expectancy) significantly predicted actual tolerance, whereas expected danger significantly predicted avoidance. These findings are in partial agreement with previous research. Among the clinical implications are that chronic pain sufferers generally associate pain with damage and they predict their pain tolerance well; they do not necessarily escape from a compulsory activity that produces pain, but given the chance they would rather avoid it in the first place.

Avoidance Learning↗
PubMed1980

Biochemical Changes in Tuber-bearing Solanum Species in Relation to Frost Hardiness during Cold Acclimation.

Biochemical changes in potato leaves during cold acclimation have been examined and compared between a frost-tolerant S. acaule and a frost-susceptible S. tuberosum species. Changes were also examined in S. tuberosum, S. acaule, and S. commersonii species when they were hardened at different temperatures to varying hardiness levels.During three weeks of stepwise cold acclimation, S. acaule increased frost hardiness from -6.0 C (killing temperature) to -9.0 C, whereas frost hardiness of S. tuberosum remained unchanged at -3.0 C. Decreases in DNA content on a dry weight basis in both species suggest that matured leaf cells accumulated more dry matter during acclimation. The advantage of using DNA as a reference for comparing metabolite changes during cold acclimation is discussed.Under the stepwise acclimating conditions, both species showed the same trends for increasing total sugar and starch with an insignificant decrease in leaf water content. High levels of total RNA, rRNA, and total and soluble protein were observed in treated S. acaule plants as compared with controls, but not in S. tuberosum. Levels of total lipid and phospholipid also were high in treated S. acaule plants as compared with controls but decreased in S. tuberosum during acclimation.When S. tuberosum, S. acaule, and S. commersonii potatoes were cold-treated at constant day/night temperatures of 10, 5, and 2 C with 14-hour daylength, each species responds differently in terms of frost hardiness increase upon subjecting plants to a low temperature. For instance, after 20 days at 2 C, a net frost hardiness of 3 and 7 C was observed in S. acaule and S. commersonii, respectively, whereas the frost hardiness in S. tuberosum remained unchanged. Also, various levels of frost hardiness can be achieved in a species by subjecting plants to different low temperature treatments. Under a warm regime of 20/15 C day/night temperatures (14-hour light), both S. acaule and S. commersonii can survive at -4.5 C or colder, whereas S. tuberosum can survive only at -2.5 C.Biochemical changes in the leaf tissue of these species were investigated at 5-day intervals during low temperature treatments. Increases in total sugar and starch were found in all three species during hardening, although S. tuberosum failed to harden. Soluble protein contents were increased in both S. acaule and S. commersonii but decreased in S. tuberosum. RNA contents change in a pattern similar to the soluble protein. Net increases of the soluble proteins were positively and significantly correlated with net increases of frost hardiness in S. acaule and S. commersonii.

Journal Article↗