Preserving US microbe collections sparks future discoveries

Collections of micro‐organisms are a crucial element of life science research infrastructure but are vulnerable to loss and damage caused by natural or man‐made disasters, the untimely death or retirement of personnel, or the loss of research funding. Preservation of biological collections has risen in priority due to a new appreciation for discoveries linked to preserved specimens, emerging hurdles to international collecting and decreased funding for new collecting. While many historic collections have been lost, several have been preserved, some with dramatic rescue stories. Rescued microbes have been used for discoveries in areas of health, biotechnology and basic life science. Suggestions for long‐term planning for microbial stocks are listed, as well as inducements for long‐term preservation.

Establishing a database of Canadian feline mitotypes for forensic use

Hair shed by pet animals is often found and collected as evidence from crime scenes. Due to limitations such as small amount and low quality, mitochondrial DNA (mtDNA) is often the only type of DNA that can be used for linking the hair to a potential contributor. mtDNA has lower discriminatory power than nuclear DNA because multiple, unrelated individuals within a population can have the same mtDNA sequence, or mitotype. Therefore, to determine the evidentiary value of a match between crime scene evidence and a suspected contributor, the frequency of the mitotype must be known within the regional population. While mitotype frequencies have been determined for the United States' cat population, the frequencies are unknown for the Canadian cat population. Given the countries' close proximity and similar human settlement patterns, these populations may be homogenous, meaning a single, regional database may be used for estimating cat population mitotype frequencies. Here we determined the mitotype frequencies of the Canadian cat population and compared them to the United States' cat population. The two cat populations are statistically homogenous, however mitotype B6 was found in high frequency in Canada and extremely low frequency in the United States, meaning a single database would not be appropriate for North America. Furthermore, this work calls attention to these local spikes in frequency of otherwise rare mitotypes, instances of which exist around the world and have the potential to misrepresent the evidentiary value of matches compared to a regional database.

Neurobehavioral alterations in HIV-1 transgenic rats: evidence for dopaminergic dysfunction

Clinical studies have provided evidence that the progression of HIV-1-associated neurocognitive disorders (HAND) involves alterations in dopamine (DA) systems. Drugs of abuse that act on the brain DA system, such as cocaine (Coc), may exacerbate HIV-1 infection and consequent behavioral and neurological manifestations. In the present study, we used the HIV-1 transgenic (Tg) rat, which constitutively expresses 7 of the 9 HIV-1 genes, to assess potential DA system alterations in three behavioral assays: prepulse inhibition (PPI) of the auditory startle response (ASR), novelty and habituation/retention, and sensitization to Coc across repeated administration. Adult female Sprague-Dawley rats were tested in each experiment. The HIV-1 Tg animals were hyperreactive to auditory startle stimuli and displayed a leftward shift in the temporal window for maximal PPI, suggesting an alteration in sensorimotor gating. All animals displayed an initial robust locomotor response to a novel environment which dissipated with repeated testing; however, the HIV-1 Tg rats, relative to controls, consistently showed a weaker novelty response across monthly-spaced assessments. The HIV-1 Tg animals also showed decreased intrasession habituation of motor activity across 3-day periods that emerged across monthly-spaced locomotor activity sessions; a pattern consistent with impaired long-term episodic memory. Furthermore, the HIV-1 Tg group displayed differential cocaine-induced sensitization, observed both in initiation across the 10-day cocaine treatment, and in expression following a cocaine rechallenge after a 7-day abstinence. Collectively, the present data implicate that the non-infectious HIV-1 Tg rat, which resembles the complete suppression of infection in HIV-1 positive individuals under CART, displays sustained, if not permanent, alterations in the brain DA system.

A benefit of high temperature: increased effectiveness of a rice bacterial blight disease resistance gene

*Continuous planting of crops containing single disease resistance (R) genes imposes a strong selection for virulence in pathogen populations, often rendering the R gene ineffective. Increasing environmental temperatures may complicate R-gene-mediated disease control because high temperatures often promote disease development and reduce R gene effectiveness. Here, performance of one rice bacterial blight disease R gene was assessed in field and growth chamber studies to determine the influence of temperature on R gene effectiveness and durability. *Disease severity and virulence of Xanthomonas oryzae pv. oryzae (Xoo) populations were monitored in field plots planted to rice with and without the bacterial blight R gene Xa7 over 11 yr. The performance of Xa7 was determined in high- and low-temperature regimes in growth chambers. *Rice with Xa7 exhibited less disease than lines without Xa7 over 11 yr, even though virulence of Xoo field populations increased. Xa7 restricted disease more effectively at high than at low temperatures. Other R genes were less effective at high temperatures. *We propose that Xa7 restricts disease and Xoo population size more efficiently in high temperature cropping seasons compared with cool seasons creating fluctuating selection, thereby positively impacting durability of Xa7.

Serological survey of pre-weaned New Zealand fur seals (Arctocephalus forsteri) for brucellosis and leptospirosis

AIM

To conduct a longitudinal serological survey for evidence of Brucella spp and Leptospira spp infection of pre-weaned New Zealand fur seals in a colony on the Otago Peninsula.

METHODS

Seal pups were repeatedly captured on a monthly basis from February through to July 2001. Pups were tagged at first capture and a blood sample was taken at each capture event. A total of 163 sera were collected from 118 seal pups. Where sufficient volume was collected, the sera were tested for leptospirosis using the microscopic agglutination test (MAT), and for brucellosis using the competitive enzyme-linked immunosorbent assay (ELISA) for Brucella abortus.

RESULTS

None of 128 sera from 101 seals tested positive to the ELISA for B. abortus. All tests for Leptospira interrogans serovars Grippotyphosa, Copenhageni, Bratislava and Leptospira borgpetersenii serovar Ballum were negative at a cut-off of <1/100 dilution. Positive or suspicious titres were found to L. interrogans serovars Canicola and Pomona and L. borgpetersenii serovar Hardjo. The highest titres (12,800) were found to serovar Pomona. The titre to serovar Pomona in one seal rose from <1/50 in March to 12,800 in April and was <1/50 when re-sampled in July. The titre to serovar Pomona in another seal dropped from 12,800 in May to <1/50 in June. These seals also had titres to serovar Hardjo, which rose or fell in the same manner. All suspicious or positive titres occurred in late April and early May, when the pups were approximately 4-5 months old. In June and July, all seals tested were negative.

CONCLUSIONS

There was no serological evidence of Brucella infection in the pre-weaned fur seals at the colony. Positive titres to serovars Pomona, Hardjo, or Canicola suggest that a Leptospira species was present at the colony, however isolation or visualisation of the organism is required to confirm this. Care should be exercised when handling New Zealand fur seals to prevent human infection or inadvertent transfer of leptospirosis to another marine mammal species.

Decreased recurrent carotid stenosis by routine patching and intraoperative scanning

Our objective was to review the results of carotid endarterectomies (CEAs) with Dacron patch angioplasty and intraoperative color-flow duplex scanning (CFS). In a 3-year period, patients who underwent CEA with Dacron patch angioplasty and intraoperative CFS were studied. We excluded patients who had primary closure, vein patch, and redo endarterectomy. Serial CFS was obtained first in the early postoperative period (one day to 3 weeks), then at 6 months, and then yearly. Intraoperative CFS abnormalities were classified as major, requiring immediate revision, or minor, which were observed. The diagnosis of recurrent stenosis by US was based on the detection of an increased peak systolic frequency (>8000 MHz) or velocity (>250 cm/second) in the internal carotid artery. There were 212 CEAs performed in 200 patients (128 men and 84 women) included in this study. Three patients (1.4%) awoke with a stroke, two (0.94%) had transient ischemic attacks, and three (1.4%) developed transient hypoglossal nerve paresis. Intraoperative CFS showed a major defect that required an immediate revision in six patients (2.8%). Minor abnormalities were detected in another 41 patients (19.3%), but no revision was necessary. In follow-up three patients were identified with a severe recurrent carotid stenosis (>80%) and they underwent redo CEA. This rate of recurrence (1.4%) is significantly lower than the rate we had previously reported in a larger study (82 of 1209, 6.8%; P = 0.003). We conclude that the combined use of Dacron patch angioplasty and intraoperative CFS after CEA is associated with a low perioperative morbidity and a low incidence of recurrent stenosis in the first 2 years after operation.

Calcitonin and spinal fusion

The authors report on the efficacy of nonsurgical treatment of an older patient with a fractured odontoid process. The patient, an 85-year-old woman, had multiple medical problems that put her at an increased surgery-related risk. Therefore, an alternative approach was elected, including immobilization with a Philadelphia collar and the provision of calcitonin nasal spray. Bone union and clinical recovery were achieved within 8 weeks of initiating the nasal calcitonin therapy (12 weeks postinjury). Considering the patient's age, comorbidities, and the severity of the fracture, the recovery period was unusually short. The authors believe that calcitonin played a pivotal role in the healing process of the fractured odontoid bone. There is no question that the fusion in this patient could be unrelated to the medical therapy. This description of one patient, as well as the lack of a large randomized study, precludes any scientific conclusions. Nevertheless, the authors believe that the development of a successful fusion in this high-risk patient should be reported as an observation that merits confirmation and study. The authors also discuss the physiological effects of calcitonin and the research and clinical experience with this hormone in different conditions affecting bone.

Results of transsphenoidal surgery for Cushing's disease in patients with no histologically confirmed tumor

OBJECTIVE

Pathological confirmation of surgical resection of an adenoma for Cushing's disease is not always achieved. We reviewed our experience to determine the prognostic significance of this lack of confirmation regarding outcome, and we evaluate explanations for this situation.

METHODS

The records of all patients undergoing transsphenoidal surgery for Cushing's disease from 1992 to 1998 were reviewed, and those with no histological confirmation of tumor were identified. Information regarding preoperative and postoperative hormonal levels and clinical symptoms, preoperative magnetic resonance imaging data, intraoperative findings, and the number of reoperations were recorded.

RESULTS

There were 29 patients with no confirmation of tumor. Nineteen (66%) of these patients were cured with surgery and only one had a recurrence of disease, with an average follow-up of 38 months. An abnormality thought to represent an adenoma at the time of surgery was removed in 26 patients (90%). Preoperative magnetic resonance imaging suggested a discrete lesion in 21 patients (72%). Neither intraoperative impression nor magnetic resonance imaging appearance was correlated with outcome.

CONCLUSION

Patients with no histological confirmation of tumor after transsphenoidal surgery for Cushing's disease are likely to have a good outcome. The results do not differ significantly from reported cure rates in patients with confirmed adenomas. Possible explanations for this situation are discussed.

Patterns and distribution of isolated calf deep vein thrombosis

PURPOSE

In the search for calf deep vein thrombosis (DVT) with color-flow duplex scanning (CFDS), most vascular laboratories investigate only the posterior tibial and peroneal veins. Few laboratories assess the soleal and gastrocnemial veins. This study was designed to determine the patterns and distribution of isolated calf DVT, including the soleal and gastrocnemial veins.

METHODS

In the last 3 years, 5250 patients (mean age, 66 +/- 15 years; range, 22 to 93 years) were referred to the vascular laboratory for clinical suspicion of DVT and underwent examination with CFDS. All superficial and deep named veins, excluding the anterior tibial from groin to ankle, were imaged. Of the deep veins in the calf, the peroneal, the posterior tibial, the gastrocnemial, and the soleal veins were examined throughout their length.

RESULTS

DVT was detected in 14% of the patients. Isolated calf DVT was detected in 282 limbs of 251 patients (4.8%). No significant difference was noted for the sex (114 men vs 137 women; P =.15) or the limb preference (145 left vs 137 right; P =.5). The peroneal veins were most frequently involved, with 115 limbs (41%) affected. The soleal veins were involved in 109 limbs (39%), followed by the posterior tibial in 105 limbs (37%) and the gastrocnemial in 79 limbs (29%). Thrombus in the soleal vein alone was found in 57 limbs (20%), in the gastrocnemial in 48 limbs (17%), in the peroneal in 41 limbs (15%), and in the posterior tibial vein in 35 limbs (12%). Thrombus confined to a single or paired vein was found in 181 limbs (64%). Thrombus involving two different veins (27%) was the second most frequent pattern, and thrombus in three (7%) or four (1.4%) different veins was less prevalent. Isolated thrombosis in veins not routinely investigated was found in 113 limbs (40%; soleal, n = 57; gastrocnemial, n = 48; soleal + gastrocnemial, n = 8). Multifocal origin of thrombosis, defined as thrombi in two different veins that do not anatomically communicate, was identified in 63 limbs (22%).

CONCLUSION

Forty percent of the patients with acute isolated calf DVT would be judged to have normal CFDS examination results if the muscular veins in the calf were not imaged. Multifocal origin of thrombosis was found in 22% of the involved limbs. The prevalence of thrombosis in any calf vein either alone or in combination is comparable. Accordingly, the soleal and gastrocnemial veins should be examined routinely.

Timing and frequency of perioperative carotid color-flow duplex scanning: A preliminary report

PURPOSE

The results of intraoperative and early postoperative carotid color-flow duplex scanning (CFS) after endarterectomy were reviewed to determine whether any perioperative studies could be eliminated.

METHODS

Patients undergoing carotid endarterectomy with intraoperative CFS between 1986 and 1997 were identified. Early postoperative CFS was performed between 1 day and 3 weeks postoperatively, then it was performed again at 6 months postoperatively.

RESULTS

During the study period, 560 patients, 325 men and 235 women, underwent 621 carotid endarterectomies. A satisfactory intraoperative carotid CFS was completed in 611 (98.4%) patients. There were 20 (3.2%) vessels with a major defect that required revision for fronds or flaps (n = 11), retained atheroma (n = 5), low flow (n = 2), high velocity or turbulence (n = 1), or dissection (n = 1). Another 146 vessels (23.5%) had minor defects, such as retained proximal atheromas or small (less than 3 mm) fronds, but were not revised. The remaining 445 vessels were normal. The first postoperative CFS was normal in all the revised carotids and in 138 (94.5%) vessels with minor intraoperative defects. At 6 months, recurrent stenosis (more than 75% area reduction) was identified in 1 of 18 revised carotids (5.5%), 4 of 138 vessels (2. 9%) with minor defects, and 17 of 406 vessels (4.2%) that were normal intraoperatively. The incidence of recurrent stenosis was not significantly different in the three groups (P =.7).

CONCLUSION

Intraoperative CFS is useful because major unsuspected defects can be corrected immediately, thus avoiding potential neurologic morbidity. However, the postoperative day 1 CFS can be eliminated in most cases, because it does not provide any relevant clinical information.

An improved computer model of struvite solution chemistry

The computer model of the solution chemistry of struvite has been improved. Firstly, with ammonia as the prime calculation point in the liquid phase, the algorithm is smaller and faster. Secondly, the incorporation of distilled magnesium hydrogen phosphate in the model significantly increased the concentrations in solution. Thirdly, estimates of the activity coefficients are included. These improvements have but a marginal (5-10%) improvement in the fit. However, proceeding with this flexible modelling procedure using the symbolic manipulator, Maple, easily allows the inclusion of all possible species. The addition of associated ammonium phosphates improves the fit. The relative standard deviation of the fit of both Taylor's data and the data of Webb is improved from 0.5 to 0.2. Estimates of the association constants are included.